# Opposed twin Onan engine in half scale



## teeleevs (Nov 25, 2020)

I am a member of a model train Club in S E Queensland, Australia, we give kids rides on our model railways, Steam engines are popular but beyond some of us. I have built a Fairmont 6 man Gangers trolley powered by a mower engine. It does real work pulling up to 16 people on our 7 & 1/4 inch track.


----------



## teeleevs (Nov 27, 2020)

This is a steam engine.  You can tell the men from the boys by the size of the toys.


----------



## teeleevs (Nov 27, 2020)

Todays work on the Onan opposed twin, see castings page, working on the crankshaft,  photo 1 setting up for turning between centres,  2 centre drilling,  3 reducing the weight,  4 turning the crankpin.


----------



## teeleevs (Dec 2, 2020)

More work on the crankshaft since last post, 1/ & 2/ second crank pin on track, went over to my big 4 jaw chuck, 3/ this is a large chuck, have only used it once this century, 4/ pieces coming together. 
 Thanks for watching


----------



## teeleevs (Dec 3, 2020)

More on the Onan opposed twin, picture 1/ nearly ready to press together, so far I have reduced a 20 pound piece of 3 inch round bar to just 4.2 pound i e about 2 kg, 2/ a good piece of Queensland Rail steel becoming connecting rods, 3/ boring the bigends and litttlends.


----------



## teeleevs (Dec 4, 2020)

Todays progress, photo 1/ setup between centres on Gils Harrison Lathe 2/ the shape beginning to appear 3/ conrods finished one Honda piston fitted, roller bearings fitted 4/ crankshaft ready for assembly. Thanks for watching, Ted from down under


----------



## ignator (Dec 4, 2020)

I'm watching your build with interest. I have a Onan that used to power my skid steer loader, a Hydra-Mac from 1972. The engine is a 25HP NC model. It suffered from the common failure of exhaust valve seat coming loose. And when Cummings purchased them a few years back, they stopped all support of the existing engines.
I was able to bore my cylinders on my vertical milling machine back 25 years ago, to 0.030 oversize. 
There was a design flaw by the Hydra-Mac skid steer design, they used a triple V-belt pulley to drive the hydrostatic pump/motors (Sunstrand Model U), this put too much radial forces on the power take off shaft, which only had a babbitt bearing, not intended for these forces, which produced early wear out. 
Looks like your using ball bearings in your crank interface.
I'm interested in how you build the cylinders. The original engine I have has cast iron sleeves that were cast into the aluminum block.


----------



## teeleevs (Dec 4, 2020)

Thanks ignator, I have some 2inch cast iron to make the sleeves, the Honda pistons are 39mm, the alloy cylinders will be built up from cast pieces, the valve guide and seat will be one piece glued in with J B Weld, picture 1/ polystyrene pattern, 2/ a casting, the fins will be cut in the mill once I know where the bolts go. Some of my pictures are under another guys thread Building a Flat Twin, and some are under Castings.  My only experience with the full size engine was back in 1963 direct coupled to a Lincoln welder and 1974 I owned one myself, the unit bolted down in the back of my Land Cruiser was so handy with its 240 volt power outlets. 
Ted from down under


----------



## ignator (Dec 4, 2020)

teeleevs said:


> Thanks ignator, I have some 2inch cast iron to make the sleeves, the Honda pistons are 39mm, the alloy cylinders will be built up from cast pieces, the valve guide and seat will be one piece glued in with J B Weld, picture 1/ polystyrene pattern, 2/ a casting, the fins will be cut in the mill once I know where the bolts go. Some of my pictures are under another guys thread Building a Flat Twin, and some are under Castings.  My only experience with the full size engine was back in 1963 direct coupled to a Lincoln welder and 1974 I owned one myself, the unit bolted down in the back of my Land Cruiser was so handy with its 240 volt power outlets.
> Ted from down under


I used J B Weld to repair the valve seat. I made a new one using O2 tool steel. I never could find what sort of steel the hardened seat inserts were made of. So I used what I had in my shop. It worked, but I got the press fit size a bit small, as it came loose again after 20 hours of running. So I used the epoxy to put it back. It held until I replaced the engine with a Honda back in 2011. All was well, but doing some earth moving for a new shop I wanted to build this summer, I broke some spur gear in the drive train. I have not disassembled to see what is damaged. Parts can be had for much money. It was very close to one of the original skid steers ever produced in the USA. Previous owner abused it. I could see where repairs were only made when it would not move. Pig farm operation, cleaning out manure.
So your casting, do you leave the foam in place which is melted and vaporized during the pour?


----------



## teeleevs (Dec 5, 2020)

Yes that is the way it is done, a bit like lost wax casting, the job turns out a little rough but I need finer sand. I have used wood patterns with good results but sometimes it very difficult to make a shape that will come out of the mold without making complicated cores. All good fun. 
Thanks
Ted


----------



## teeleevs (Dec 7, 2020)

Thanks ignator, valve seats should be no problem as any auto repair/ rebuild shop have them in all different sizes. Photos today 1/ trueing up the crank 2/ almost finished the final cutting, only have to split it up and mount the conrods then Locktite final assembly trueing it up as I go.


----------



## ignator (Dec 7, 2020)

teeleevs said:


> Thanks ignator, valve seats should be no problem as any auto repair/ rebuild shop have them in all different sizes. Photos today 1/ trueing up the crank 2/ almost finished the final cutting, only have to split it up and mount the conrods then Locktite final assembly trueing it up as I go.


I recall seeing your CAD drawing having fasteners to hold the crank shaft conn rod throws in place. Appear to be flat head screws. I would have thought in this size engine the inertia impulses from throwing the pistons would shake this apart.

Well for valve seats, I have lathe, and local engine shop was not wanting to help me unless I let them do the machine work. So I was more interested in what hardness the seats were. This was back in 2007, and I could not find any links on the internet that had tool steel material type and Rockwell hardness level. I have a Black and Decker valve seat grinder and valve grinder dating from the 1960s. 
The Onan did not lap the valve seat, at least on my NHC model. The made the valve 44 degree and the seat 45 degrees, call this an interference angle. The attachments are from the shop manual below: Probably nothing new here for you, but someone else reading this may gander some useful information.


----------



## teeleevs (Dec 7, 2020)

I hope you are wrong but the crank pin is only 12mm so putting it in tension under an 8mm countersunk bolt will stiffen it up, I have built another engine that only has an 8mm bolt through a ballrace bearing with a locknut and it runs fine.  I worked for a service station back in 1968 and used the Black and Decker Valve Facer quite often.  But when the valve is only 14mm diameter it is hard to achieve a good seal when the seat is produced with a drill at 30 degrees, still one manages. photo 1 the model and 2 the real 1898 machine used on the Normanton line in Far North Queensland, Australia.


----------



## ignator (Dec 7, 2020)

teeleevs said:


> I hope you are wrong but the crank pin is only 12mm so putting it in tension under an 8mm countersunk bolt will stiffen it up, I have built another engine that only has an 8mm bolt through a ballrace bearing with a locknut and it runs fine.  I worked for a service station back in 1968 and used the Black and Decker Valve Facer quite often.  But when the valve is only 14mm diameter it is hard to achieve a good seal when the seat is produced with a drill at 30 degrees, still one manages. photo 1 the model and 2 the real 1898 machine used on the Normanton line in Far North Queensland, Australia.


It was more of a question as to if this is sturdy enough. You have experience with this sort of crankshaft build. Every engine I've seen that is production has a forged crank, even the very small engines used in weed wackers, and leaf blowers. I can see this working without issue in a miniture model, but I'm curious about larger engines. My experience with a crank build a few years back stopped me as I could not make it run true. I'm going to have to get back to that. It was for a Stirling engine. So I'm trying to see how it's done here, as there is much success.


----------



## teeleevs (Dec 8, 2020)

As you say, it is very difficult to make it run true, I am yet to find out if I am successful. I found on the drawing board that there was insufficient clearance between big-ends and the cams so opted for roller bearings without bolts through, I might yet regret that decision. On your full sized model, the 15 HP up to 20 HP had ordinary car like big-ends but when they lengthened the stroke they ran into the same problem.


----------



## teeleevs (Dec 11, 2020)

Last couple of days work on the Onan opposed twin, 1 the rear bearing housing, drilled one hole in the wrong place? 2/3 decided to lighten the rods, poor little pistons are the lightest parts in the whole project. 4/5 cutting an oil groove.  6 looking good


----------



## teeleevs (Dec 11, 2020)

Some may question the rotary table? I was given a 97 tooth gear about 30 years ago. What can you do with a 97 tooth gear?  It is mild steel, I counted the teeth on a Holden ringgear 135, cut 15 out and carefully pulled it in and welded it, giving me 120 teeth which can be divided by numerous numbers.  Turned part of the 97 teeth away, fitted the ringgear, had a worm wheel that fitted,  onto that I can fit any combination of lathe change wheels or drive it with a motor. Drilled holes and threaded 3/8 W


----------



## ignator (Dec 11, 2020)

teeleevs said:


> Last couple of days work on the Onan opposed twin, 1 the rear bearing housing, drilled one hole in the wrong place? 2/3 decided to lighten the rods, poor little pistons are the lightest parts in the whole project. 4/5 cutting an oil groove.  6 looking good


Those connecting rods look super duty! Interesting 4 jaw setup to carve them.


----------



## teeleevs (Dec 11, 2020)

Yes Ignator, a bit of overkill, I'm sure they won't bend in a hurry. 
Ted.


----------



## teeleevs (Dec 14, 2020)

Another day on the Onan opposed twin half scale.  Photo 1 I have set up the crankcase on a spigot to turn true bolted the timing case on and bored through for the crankshaft, faced back the case ready to fit the Lifan Chinese ignition coils and flywheel, photo 2 turning the seal seat inside the timing case. 
Ted from down under


----------



## ignator (Dec 14, 2020)

teeleevs said:


> Some may question the rotary table? I was given a 97 tooth gear about 30 years ago. What can you do with a 97 tooth gear?  It is mild steel, I counted the teeth on a Holden ringgear 135, cut 15 out and carefully pulled it in and welded it, giving me 120 teeth which can be divided by numerous numbers.  Turned part of the 97 teeth away, fitted the ringgear, had a worm wheel that fitted,  onto that I can fit any combination of lathe change wheels or drive it with a motor. Drilled holes and threaded 3/8 W


I do not see where you partially removed the 97 teeth, and slipped on the modified ring gear. That must have taken some doing to keep the 'shrunken' ring gear from getting a kink vs a round gear. 
I guess I cheated by buying a H/V rotary table. Vertex brand made in Taiwan. I mounted a 10 inch 3 jaw chuck on it's 12 inch table. Very heavy and have to use the overhead shop bridge crane to put it on the milling table.


----------



## ignator (Dec 14, 2020)

teeleevs said:


> Another day on the Onan opposed twin half scale.  Photo 1 I have set up the crankcase on a spigot to turn true bolted the timing case on and bored through for the crankshaft, faced back the case ready to fit the Lifan Chinese ignition coils and flywheel, photo 2 turning the seal seat inside the timing case.
> Ted from down under


Interesting setup to start the machining of the timing case spigot. I assume you supported this with the tailstock. Did you 'carve' out the internals of the timing cover all on the lathe?
For size reference how big is the 3 jaw on your lathe? Appears to be 12 inch diameter.


----------



## teeleevs (Dec 14, 2020)

The chuck is 10 inch, I  cast the timing cover from lost foam, photo 1 in the green sand ready for the next box, 2 shows the internal shape,  3 the outer shape, 4/5 it came out very rough but it is cleaning up OK. The ringgear I slowly bent in the vice until it nearly metup then I clamped it in place using several clamps then welded the join and a few tacks around, all went well.


----------



## teeleevs (Dec 14, 2020)

The crankshaft? Most weed eaters have a single shaft through 2 bearings then a plate with an open crankpin, much like the model aero engine, some motorcycle crankshafts are made up with roller bearings and all pressed together, even multiple cylinder ones,  the Suzuki 3 cylinder 2 stroke Jeep engine the same, but they have better equipment and jigs than I have.


----------



## teeleevs (Dec 15, 2020)

Todays progress on the Onan opposed twin half scale engine. Photo 1 fitting the Lifan Chinese magnito, 2 machining the base for the magnito on the timing cover, 3 how to get it all the right shape, this photo more detail of the rotery table can be seen, 4, 5, & 6 travel stops on the  old lathe. 4 each number represents 1/4 millimeter approx 10 thou 0.010".  5 each mark approx 2thou 0.002 on a 10x1.5mm booker rod thread. The spring presses a ball bearing on the thread to prevent unwanted movement. 6 final cuts for the seal seat.
Ted


----------



## ignator (Dec 15, 2020)

teeleevs said:


> Todays progress on the Onan opposed twin half scale engine. Photo 1 fitting the Lifan Chinese magnito, 2 machining the base for the magnito on the timing cover, 3 how to get it all the right shape, this photo more detail of the rotery table can be seen, 4, 5, & 6 travel stops on the  old lathe. 4 each number represents 1/4 millimeter approx 10 thou 0.010".  5 each mark approx 2thou 0.002 on a 10x1.5mm booker rod thread. The spring presses a ball bearing on the thread to prevent unwanted movement. 6 final cuts for the seal seat.
> Ted


Ted, I had to look up Booker Rod. Appears to be different spelling of Brooker (internet say's Booker is Australian and German spelling). But in the States, it's called All Thread rod, or local colloquial as Redi Rod.
That's an interesting feed control method. Is the cross feed screw worn out so you don't trust it on the lathe? I guess I'm spoiled as I have DRO's on all the machines in the shop. But I still find I have to measure twice, as you don't always get the feed you want. So if I don't want scrap, I have to sneak up on it.
I do work in both Metric and Imperial (SAE), as I measure in the units that thing I'm fixing was made in. That said most digital measuring tools, use Metric scales, and convert to inch, loosing some resolution.
So your magneto appears to be an alternator, and not the type that controls spark to the high voltage coil. Unless that one coil that has wrapped insulation is the high voltage source. If not, There must be a rectifier, feeding the ignition. So I assume there is an ignition system, where shaft location sensor controls spark timing. Unless you have points in this somewhere. I know that Onan fired both spark plugs simultaneously, as the high voltage coil was in series with both of them, and engine block closed that secondary coil circuit through the airgap of the plugs.


----------



## haakonpe (Dec 15, 2020)

Where did you get the plans for this?


----------



## ignator (Dec 15, 2020)

teeleevs said:


> The crankshaft? Most weed eaters have a single shaft through 2 bearings then a plate with an open crankpin, much like the model aero engine, some motorcycle crankshafts are made up with roller bearings and all pressed together, even multiple cylinder ones,  the Suzuki 3 cylinder 2 stroke Jeep engine the same, but they have better equipment and jigs than I have.


Yes, I've seen some 2 strokes have pressed cranks. and they are high RPM types, which surprises me.
My previous two autos were based on the Suzuki 3 cylinder 1 liter engines. The first one got 57MPG, it was made in Japan, but sold by Chevrolet as a Sprint ER model, that was a 1987, then next one was a 1998 Chevy Metro, but only got 40MPG, as they went from carburetor to throttle body fuel injection, and they added 800 lbs to the chassis weight to make it crash worthy. And as always they worry more about the odd emissions and controlling them, then the emissions per mile, so fuel efficiency suffers.


----------



## teeleevs (Dec 15, 2020)

Hi ignator, yes I thought that "Booker rod" would cause some comments, My 1890s lathe has a 6TPI Cross feed screw and the marks (if they can be seen) represent 0.017 off the diameter, not counting backlash, not very useful.  The Lifan setup is an alternator with a magnetic pickup for the ignition so battery and starter are on the drawing board, I have been able to get all, rectifier, CDI unit, on eBay, I have a twin lead coil from an early Honda bike so lost spark ignition should not be a problem.
The 2 rebadged Suzuki cars you mention would be 4 stroke and have auto type shell bearings on the crankshaft but my Suzuki tractor is 2 stroke so is all different, will have to add a post from my computer about the tractor (Type in Articulated tractor homemade ) you will find it among the thousand or so that Google will bring up.
Hi haakonpe, I have drawn some 2d drawings in TurboCAD (no expert ) but mostly I have to adjust things as I go along and avoiding having 2 bolts occupying the same small piece of metal has become a game of hide and seek. Google is a Godsend and I found a lot of parts of the full sized machine to copy or get ideas from. I have worked in the bush (sticks) and made do with whatever is at hand during my working life so I continue on in retirement. I can put my drawings on this page if it will help. 
Ted from down under


----------



## teeleevs (Dec 15, 2020)

Hi guys, This is the Youtube item for my tractor 
Since then my friend and I gave it a full makeover. It will mow grass at 12 KPH, The Suzuki engine is facing backwards, 2 gearboxes are running backwards and the 2 diffs are upsidown so it runs forward. There are forty speeds 14 of them reverse, if game (stupid) it can do 60 KPH but I have blocked out Reverse in Gearbox 1 and blocked our top gear in both gearboxes which leaves me with a manageable selection of speeds. I think that is enough for this time.
Ted


----------



## ignator (Dec 16, 2020)

teeleevs said:


> Hi guys, This is the Youtube item for my tractor
> Since then my friend and I gave it a full makeover. It will mow grass at 12 KPH, The Suzuki engine is facing backwards, 2 gearboxes are running backwards and the 2 diffs are upsidown so it runs forward. There are forty speeds 14 of them reverse, if game (stupid) it can do 60 KPH but I have blocked out Reverse in Gearbox 1 and blocked our top gear in both gearboxes which leaves me with a manageable selection of speeds. I think that is enough for this time.
> Ted



Ted, your video was entertaining (Gilson kept the 'play by play'). So what did this Suzuki engine power originally? I'm guessing you modified an existing hobby farm tractor. I saw a hydraulic pump, looks like power steering.
I do the same thing with scrap. I just hauled in 727 lbs. of lead acid batteries. I got US$0.17/lb. They needed to go years ago.


----------



## teeleevs (Dec 16, 2020)

ignator said:


> Ted, your video was entertaining (Gilson kept the 'play by play'). So what did this Suzuki engine power originally? I'm guessing you modified an existing hobby farm tractor. I saw a hydraulic pump, looks like power steering.
> I do the same thing with scrap. I just hauled in 727 lbs. of lead acid batteries. I got US$0.17/lb. They needed to go years ago.



The engine was from an LJ50 Jeep these came out from Japan in 1974, my brother bought one of the first to arrive here, they were very small 540 cc so they were probably never seen in the US. this one had an oil leak in the feed to centre cylinder so little end bearing went, there was no way to replace the rod so I finished up with the engine and a whole lot of other bits, it still ran but rattled a bit, he used to put a new wrist pin bearing in every now and again, I later finished with a whole used crankshaft.  I built up the whole tractor from parts scrounged from work or scrap yards, in the 80s one could wander through a scrap yard and load up a trailer paying scrap price on the way out, those days are gone.    The power steering came from a Holden V8 about 1962 model, the Toyota Crown axles were cut down to fit in a 6x4 garden trailer, an extra Toyota gearbox between the Suzi gearbox and the Suzi transfer box, have to get some photos, I have it at my friend Gil's place at the moment, one trouble to address is when steered to end of travel it rips into the power steering belt so need to devise stops on the steering wheel to prevent it being held hard against the end of travel.


----------



## teeleevs (Dec 17, 2020)

Not a lot happened today, photo 1 I fitted a spacer and bored out the timing gear, drilled a hole to drop in a 1/8th ball locking the timing gear to the shaft, 2 turned the spacer/seal surface for gear to flywheel. Tried out an upside down parting tool made from a tungsten carbide tooth saw blade, it worked magic. Can't put the video on here.


----------



## ignator (Dec 18, 2020)

teeleevs said:


> Not a lot happened today, photo 1 I fitted a spacer and bored out the timing gear, drilled a hole to drop in a 1/8th ball locking the timing gear to the shaft, 2 turned the spacer/seal surface for gear to flywheel. Tried out an upside down parting tool made from a tungsten carbide tooth saw blade, it worked magic. Can't put the video on here.


You can post your video like the Suzuki tractor on YouTube or some other video hosting site, and post a link here. 
Interesting way to key the gear to the shaft. Is the ball removable without much effort?


----------



## Shopgeezer (Dec 19, 2020)

Have you got a picture of the saw parting blade?  I have often thought about something like that.


----------



## teeleevs (Dec 21, 2020)

Another day in the shop, some of my pictures have split the points and taken another track. Picture 1 drilling the crankshaft for the flywheel,  2 fitting the Lifan Chinese magnito,  3 the flywheel, 4 the fan & ringgear will fit over the flywheel. Missing pix, 5 marking out the positions of the magnito bolts  6 
 the seat for the magnito/alternator, 7 mag in place.  Merry Christmas to you all from Ted from down under


----------



## jdurnya (Dec 22, 2020)

WOW that is great !!! I restore John Deere Garden tractors and love the old Onan engines !!!     following closely !!

Joe


----------



## ignator (Dec 22, 2020)

teeleevs said:


> Another day in the shop, some of my pictures have split the points and taken another track. Picture 1 drilling the crankshaft for the flywheel,  2 fitting the Lifan Chinese magnito,  3 the flywheel, 4 the fan & ringgear will fit over the flywheel. Missing pix, 5 marking out the positions of the magnito bolts  6  the seat for the magnito/alternator, 7 mag in place.  Merry Christmas to you all from Ted from down under
> View attachment 121575






This looks like your spark timing generator. I'm not familiar with this sort. Proximity sensor type.  So does this drive a CDI that adjusts advance to the spark automatically?


----------



## teeleevs (Dec 22, 2020)

Yes Ignator, i have a new CDI box and wired it up according to the information I gleaned from YouTube but no joy.  I was given parts from a wrecked Lifan motorcycle so now I guess the reason the bike is off the road is failure of the ignition system.  EBay have listed all the ignition parts for Lifan for less than Au$50 so I haven't done all this work for nothing.  Someone asked for pix of the upsiddown parting tool, the single tooth one works best, the metal curls away down out of the way, but the adjustable multiple tooth blocks up when in deep.


----------



## ignator (Dec 29, 2020)

teeleevs said:


> Yes Ignator, i have a new CDI box and wired it up according to the information I gleaned from YouTube but no joy.  I was given parts from a wrecked Lifan motorcycle so now I guess the reason the bike is off the road is failure of the ignition system.  EBay have listed all the ignition parts for Lifan for less than Au$50 so I haven't done all this work for nothing.  Someone asked for pix of the upsiddown parting tool, the single tooth one works best, the metal curls away down out of the way, but the adjustable multiple tooth blocks up when in deep.


I've been seeing a repeated post about a spring tool (goose neck), for a parting blade holder. Very old idea from the start of the previous century. But the upside down parting blade mimics this same behavior, as when the cutting edge grabs the material, the tool post flexes back and away from the cutoff operation, instead of digging in further with conventional tool post mount. From my read, this parting operation requires a very robust lathe. Hobbyists have light duty lathes, and fight this operation. I've had my 10x24 bench lathe 'dancing' on the floor, when the lathe goes into harmonic oscillation. My fix was to procure a 2 inch thick piece of hot rolled steel and mount the lathe bolt down locations to this, and the sheet metal cabinet to the floor. This fixed all my problems.
.
I assume you're waiting on a new alternator to continue the build. Any idea what failed in your used one? I have a neighbor that repairs motocross bikes, and had an electric problem with one. I used my oscilloscope to see if the alternator was putting out 'juice'. I could capture the sine oscillations from the alternator. This went to a rectifier, and then the CDI module. In the end, he had replaced the kill switch with a normally open contact, and it required a normally closed.


----------



## teeleevs (Dec 29, 2020)

Hi Ignator, I was given parts from a wrecked Chinese bike or quad, I have no idea why it was wrecked but guess the ignition failed.  In my tries I only had the wires to the CDI and coil connected, tried several coils. Power wires to the rectifier only put out 2.5 volts AC, perhaps I should connect the rectifier and a battery, but it should spark without those.  No kill switch connected.  As for the Onan, I have been working on the ring gear and had trouble getting my head around cutting 85 teeth with a 120 tooth rotary table, watched some Youtube videos on the subject and found that both figures can be divided by 5 ie 5 x 24 = 120 and 5 x 17 = 85 I have some indexing plates somewhere put away safe? Searched for a gear and found one 17 tooth gear, just need now to build up a gear train at 24/1.
As for the up-side-down parting tool we have been using a small Bransby lathe with no back gear and the tungsten saw blade just cuts Alloy and steel like butter, must keep the lube up to it though.


----------



## teeleevs (Dec 29, 2020)

These pictures have been posted elsewhere excep #6, don't know why they are not here,  #1 lightening the rod with piston attached, #2 oil groove #3 finished job with roller bearings fitted, #4 setting up the magnito #5 flywheel in place, fan fits over this, #6 cutting teeth in the ringgear,  this gave me a headache producing 85 teeth with 120 tooth rotary table. 
Ted


----------



## teeleevs (Dec 30, 2020)

Another day on the Onan, finally got my head around the 85 tooth ringgear setup picture 1 cutting teeth, the fan needs a little more finishing and balancing, #2 the 24/17 geartrain, #3 the 17 tooth gear which goes 5 times into 85 while the 24 goes 5 times into the 120 tooth rotary table, #4 making stub shafts for the geartrain, the Bransby parting off in reverse with the upsiddown parting tool.
Happy New year to you all from Ted from down under


----------



## ignator (Dec 31, 2020)

teeleevs said:


> Another day on the Onan, finally got my head around the 85 tooth ringgear setup picture 1 cutting teeth, the fan needs a little more finishing and balancing, #2 the 24/17 geartrain, #3 the 17 tooth gear which goes 5 times into 85 while the 24 goes 5 times into the 120 tooth rotary table, #4 making stub shafts for the geartrain, the Bransby parting off in reverse with the upsiddown parting tool.
> Happy New year to you all from Ted from down under


That flywheel fan casting looks like it came from a complicated pattern.  And your gear train for a home built dividing head, very ingenious.


----------



## teeleevs (Jan 1, 2021)

Lost foam casting, thanks Ignator.


ignator said:


> That flywheel fan casting looks like it came from a complicated pattern.  And your gear train for a home built dividing head, very ingenious.


Today I finished and balanced the fan,   part of the ringgear is still rough cast making it look uneven, pictures #1 the foam pattern, 2 days work, #2 successful casting #3&4 finished ringgear, that took 5 days to a successful conclusion, happy with that. 
Thanks for watching 
Ted


----------



## ignator (Jan 3, 2021)

That flywheel turned out well balanced. Lots of carving of foam. 
You must have a full size engine your using as the model for all your parts.
I would have never thought of using a flycutter arbor for a gear tooth cutter. I'll have to keep that in mind if I ever do any gears. Oddly I have the universal dividing head in a box that I've never used. That was always a future project. 
My current project is fixing the light duty surface grinder I purchased back in 1991. Always has had spindle hop from cheap bearings and poor quality machining (which I just learned). It looks like it was originally designed for a match pair of angular contact ball bearings, but to cheapen it, they used deep groove bearings of non precision quality. The machine would make flat surfaces, but the finish had ripples. Kind of looked like a scraped surface.  I could not find a pair of angular contact bearings that had seals. So that's part of the project to modify it to keep dirt out of these expensive bearings. I found ABEC7/Class4 matched pair on eBay, same dimensions as the deep groove. I need to figure out a way to balance the motor shaft/spindle, it was balanced, but I bet to a motor only standard, and that is part of the surface finish problem.


----------



## teeleevs (Jan 4, 2021)

Ouch! oddly you get what you pay for when buying cheap machines.   No, I do not have an engine to copy, I owned one back in 1974/5 but now with Google and eBay there are plenty of parts listed for sale to Save Image As, into my computer.


----------



## ignator (Jan 4, 2021)

teeleevs said:


> Ouch! oddly you get what you pay for when buying cheap machines.


At the time, it was all that I could afford, and it predated the online used stuff for sale sites that exist now. But I guess that's my hobby, buy cheap import tools, as pre-assembled kits, and then make them work as expected. Old-iron was not available in my region back then, or was beyond my income to purchase. The two milling machines I have are old iron. One was from the 30s, and originally powered from an overhead line shaft. The previous shop that used it, put a common conversion kit available back in the 40s that powered it with a 3HP 3 phase motor (Lima). It's a horizontal mill, that sits collecting dust, as the newer vertical mill does all the real work. But I bought that in my ignorance back then. The shop owner wanted to get rid of it as it was treat for his employees to use. But the spindle speed was very slow. He said his dad purchased it new. Modern for its day, as it had power feed in all 3 axis. #2 Rockford Miller, made in Rockford Illinois. That company morphed into heavy duty automatic truck transmissions for Lorries in the 1950s. This morphed into automatic transmissions for aircraft alternators powered by turbojet engines, the idea to keep the 400Hz constant over engine idle to take off power. That has now died. But that company then got into aircraft power systems, and makes automatic circuit breaker distribution black boxes. Gone is the machine tool production it all started from. Back in their day they also made large lathes and planers. 
I don't do much repairs that require working in ten thousands of an inch, so I'm learning some things along the way. We shall see if I can make the machine better. I don't figure I can make it worse.


----------



## teeleevs (Jan 28, 2021)

Hi guys, I haven't been on for a while, had some work to do on my tractor, fitted an electric lift for the mower. Fixed some other niggling problems.  Done more on the Onan, no joy with the ignition purchased a new stater but still no joy so the new CDI box must be bad, have ordered another so we'll soon know for sure. 
5 pictures cutting a 28 tooth idler gear for the oil pump drive from bronze bushing material, I began making a steel 30 tooth but it moved and ruined then I discovered it wouldn't have worked anyway. Then amongst my "good" junk I had a 28 tooth gear but it was too narrow.


----------



## teeleevs (Jan 31, 2021)

I don't know why but my story has fragmented and some bits don't show up at all.  I purchased another CDI box and now I have spark


----------



## gadabout (Jan 31, 2021)

teeleevs said:


> Lost foam casting, thanks Ignator.
> 
> Today I finished and balanced the fan,   part of the ringgear is still rough cast making it look uneven, pictures #1 the foam pattern, 2 days work, #2 successful casting #3&4 finished ringgear, that took 5 days to a successful conclusion, happy with that.
> Thanks for watching
> Ted



Very nice work ! Can you please tell me what the sand is you are using in your casting and where you get it from.
Thanks
Mark


----------



## teeleevs (Feb 1, 2021)

Hi Mark, the sand was given to me by a fellow alloy casting experimenter because it was too course for his purpose.  It is just ordinary river sand with the appropriate quantity of bentonite added.    Bentonite can be purchased from a casting supplier in Australia, can't speak for the rest of the world.  I have screened out a lot of the coarse stones which makes for a more workable mix.    The sand mix can be used over and over but may need some Bentonite added from time to time.
Hope this is helpful
Timothy from down under


----------



## ignator (Feb 1, 2021)

Bentonite clay, I think that is the same material that is in clumping cat litter.
Or is this some other compound of bentonite?


----------



## gadabout (Feb 1, 2021)

Thanks for the reply! I am from Hobart and am using a fine sand with Bentonite added but I got the Bentonite from a farm supply house and am not happy with the results I am getting with it , mine is very light in colour , not the nice brown that yours looks! I believe there may be two types.   Am currently on the Sunshine Coast and would like to pickup some before I head home in March, really would like to get some Petrobond to try !
Regards
Mark


----------



## teeleevs (Feb 1, 2021)

Hi Mark, I have found a web site greensand.com.au the foundry is in Coburg North, Vic they also have Petrobond.     Bunnings sell Play Sand which works. Bentonite Resources mine it right here in Ipswich Qld 0754673345 bentoenviro.com.au  but it is white in colour.  and yes Clumping Cat Litter will do but you might have to wash it out of the paper or whatever it is compounded with.


----------



## teeleevs (Feb 2, 2021)

Today I repositioned the idler gear for the oil pump so that now works fine.  Timing gear at the top with grooves for the governor balls, crankshaft below,  idler gear next and oil pump at the bottom.


----------



## moose4621 (Feb 2, 2021)

Bunnings also sell "Brickies sand" which I have found to be a much finer sand than play sand giving better surface finish.


----------



## gadabout (Feb 3, 2021)

Teeleevs, I intend to visit greensand foundry supplies on my return trip but wondered if you had a source for foundry supplies up here that had eluded my searching! 

Moose4621, I have tried all of bunners sand supply and various grades from a landscape supply but not ever having foundry sand in my hand before I am not really sure if I am getting my mixes correct and using the right bentonite! 
I need to spend some time with an experienced caster to see what works! 
Regards
Mark


----------



## teeleevs (Feb 4, 2021)

More work on the Onan opposed twin yesterday, fixed a tight spot in the timing gear train.  Picture 1 Made a part for the governor pivot, 2 a spring to keep the governor balls in place when engine is stationary, 3 cleaned up the timing cover 4 fitted the fan to the flywheel, it blows a lot of wind at 400 RPM so I reckon cooling won't be a problem.  
Ted from down under


----------



## teeleevs (Feb 21, 2021)

More work on the Onan opposed twin half scale engine.  I have reached the point where I can start on the cylinder sleeves but need to be sure I can fit a friends steam engine pistons and rings into the available cast iron bar and still have enough for my two sleeves. Made up a tool to get the cylinder directly under the mill head. Picture 1 & 2 measuring tool, accuracy questionable,  3 upsiddown parting a steam engine piston, 4 turning off the rings with a tungsten carbide saw tooth.


----------



## ignator (Feb 21, 2021)

teeleevs said:


> More work on the Onan opposed twin half scale engine.  I have reached the point where I can start on the cylinder sleeves but need to be sure I can fit a friends steam engine pistons and rings into the available cast iron bar and still have enough for my two sleeves. Made up a tool to get the cylinder directly under the mill head. Picture 1 & 2 measuring tool, accuracy questionable,  3 upsiddown parting a steam engine piston, 4 turning off the rings with a tungsten carbide saw tooth.


I know the tool you need;








						Coaxial Centering Dial Test Indicator 0.250" Range 0.0005" Graduation  | eBay
					

Quick, accurate, easy centering in boring and milling set-up on horizontal or vertical machines. Speed: spindle rotation up to 800 RPM. Includes: restraining rod, center point feeler, 2", 4" & 6" straight feeler, 2", 4" & 6" curved feeler.



					www.ebay.com.au
				



But $93AU does not grow on trees (and there's probably a VAT, that is not shown on my computer screen).
Is making a cylindrical disk that is maybe .01mm smaller then your bore, with a flange to prevent it dropping down in the bore hole, with a small drill hole through the center, the intent to located the center of this cast iron sleeve material source, then use a pointed edge finder to locate under your mill spindle center a method you've thought of to get real close? (sorry for the runon sentence).


----------



## teeleevs (Feb 22, 2021)

A couple of videos, Making a steam engine piston using an upsiddown parting tool. Making piston rings using a carbide saw tooth. 
Today I made two cylinder sleeves for the Onan, 3 photos


----------



## teeleevs (Feb 24, 2021)

Today I stripped the Onan opposed twin half scale down, final assembly of the crankshaft all trued up with conrods and pistons, Locktite was used as the final belt and braces.


----------



## teeleevs (Feb 25, 2021)

Then was I in for a shock!!! Impossible to fit the crankshaft assembly into the housing with the pistons attached, no matter which way I tried. I finally resorted to cutting a piece out, firstly I  drilled and threaded M4 x 
2 holes then sawed down the threaded holes, fitted the crankshaft through, then fitted the piece back in and Liktited M4 grub screws to hold it in its original place, this patch finishes up inside the timing case, so no fear of an oil leak. I turned the register at the bottom of the sleeves 1.5mm off centre to the bore so they could be turned until the pistons run free. I  will cut the air fins after I know where the bolts go and after fitting the valves etc.  
Thanks for watching, Ted from down under


----------



## teeleevs (Feb 25, 2021)

Making piston rings using a carbide saw tooth.
Don't know what's going on but I managed to 
Upload one video here 
Ted 

https://m.youtube.com/watch?v=qfyHxjln7WE


----------



## teeleevs (Feb 25, 2021)

https://youtube.com/playlist?list=PLvhASOpnmtAXqUMrh6gHJr4OyIhBSPKL4 
Ok got it Parting off a steam engine piston using an upsiddown parting tool 
With my 19th century lathe 
Ted


----------



## teeleevs (Feb 25, 2021)

Maybe this link will work


----------



## mnay (Feb 25, 2021)

I worked for an Onan distributor many years ago.  Most people don't know but they were a division of Studebaker.
Mike


----------



## teeleevs (Feb 25, 2021)

mnay said:


> I worked for an Onan distributor many years ago.  Most people don't know but they were a division of Studebaker.
> Mike


Yes Mike, David Onan began building the opposed twin towards the end of WW2, he passed away 1958, the company was sold in 1960, Studebaker tried to change the name but Onan was so well known that people wanted to buy Onan.  The name now belongs to Cummins, although the engine is no longer built, Cummins have guaranteed the supply of spare parts for as long as there is demand.  My first involvement was with an Onan powered Lincoln welder in the Queensland Australia Main Roads Dept workshop in Central Queensland in 1963 and in 1974 I owned one myself. Very smooth running engine.


----------



## teeleevs (Mar 3, 2021)

The last few days, finally getting the cylinders in place, heads drilled and threaded. Photo 1 setup for drilling the valve positions, 2 came out exactly in line with the camshaft tunnel, looking good 4 and 5 beginning to look like an engine, 6 close-up of cylinder one.
Ted


----------



## teeleevs (Mar 3, 2021)

teeleevs said:


> Yes Mike, David Onan began building the opposed twin towards the end of WW2, he passed away 1958, the company was sold in 1960, Studebaker tried to change the name but Onan was so well known that people wanted to buy Onan.  The name now belongs to Cummins, although the engine is no longer built, Cummins have guaranteed the supply of spare parts for as long as there is demand.  My first involvement was with an Onan powered Lincoln welder in the Queensland Australia Main Roads Dept workshop in Central Queensland in 1963 and in 1974 I owned one myself. Very smooth running engine.


Actually I stand corrected, Cummins have stopped support of all existing Onan engines.


----------



## teeleevs (Mar 5, 2021)

Another day on the Onan opposed twin half scale,  got the other side done and started cutting air fins with a blade made from a tungsten carbide saw blade, two photos.


----------



## teeleevs (Mar 11, 2021)

Latest update on the Onan opposed twin half scale, cutting the air fins, photo 1,2 and 3, 4 trial assembly 5 the heads and cam followers. I have opted to leave the fins as cast, polished and lacquered in order to preserve maximum heat transfer. 
Thanks for watching Ted from down under


----------



## teeleevs (Mar 16, 2021)

Just another day in the shop,  photo 1, these are destined to become engine valves, 2 too small and too tough for normal latheing, cutting with an angle grinder, 3 I showed one to my ships engineer friend, his reaction,  "We used to sit around it playing cards on top of it, " 4 this shot shows the dipstick.
Thanks 
Ted from down under


----------



## ignator (Mar 17, 2021)

That's a clever use of construction screws for valves. They are pretty hard steel. Looks like your technique of using a cutoff wheel did a nice machining finish. Looks like your next task is to make valve seat inserts. A press fit. That's where my full size Onan had failure with the exhaust seat coming loose.


----------



## teeleevs (Mar 17, 2021)

Sorry didn't take photos today but I have made up the seat in a long tube with a step, the tube will have a bushing bronz insert then I can cut the seat and drill the guide in the one setting, JB Weld it in the hole then bore the port. Will show photos when more advanced, searched through 5 boxes of old springs and found 2 pairs suitable.  
Ted


----------



## ignator (Mar 17, 2021)

teeleevs said:


> Sorry didn't take photos today but I have made up the seat in a long tube with a step, the tube will have a bushing bronz insert then I can cut the seat and drill the guide in the one setting, JB Weld it in the hole then bore the port. Will show photos when more advanced, searched through 5 boxes of old springs and found 2 pairs suitable.
> Ted


JB Weld, I didn't know that same epoxy was available there. I used that to fix the valve seat on my Onan, and I was surprised it took the heat so well. I used starter fluid (spray can with either, to clean the parts, it's my favorite cleaning solution for everything greasy, used it yesterday to clean ball bearings of old grease).


----------



## teeleevs (Mar 17, 2021)

I thought starting fluid has a small oil content, I use Acetone for real serious cleaning. I learned that in my gem faceting hobby where even a fingerprintwas a no no, found that Ride on model trains are easier to see these days.  JB weld I used to hold the gem on the stick, it's available at Jaycar stores and eBay sales in Oz, it will stand 600 degrees ie to the melting point of aluminium. 
Ted


----------



## ignator (Mar 17, 2021)

I like acetone as well, but my skin does not. If there is oil in that either, I've never seen it, my skin is always left oil free, and I don't have any reaction to it. I also use denatured alcohol for cleaning engine grease off the truck I'm restoring. I just seem to get reactions to the real good solvents, you know, the ones that eat through nitrile gloves. When I was young I would use gasoline, but it too causes skin reaction. And I don't like the smell afterward, as well it's so darn volatile vapor wise, and heavier then air, so the fire risk is too great.
When I powder coat parts for the truck, I bake them at 400 degrees to burn off any left over hydro carbons, that seems to be the trick to a good paint job.
The JB weld failed on a gasoline filler tube repair I did on my previous car, it is incompatible with the ethyl alcohol that is added to our fuel here (10-15%).


----------



## teeleevs (Mar 19, 2021)

ignator said:


> I like acetone as well, but my skin does not. If there is oil in that either, I've never seen it, my skin is always left oil free, and I don't have any reaction to it. I also use denatured alcohol for cleaning engine grease off the truck I'm restoring. I just seem to get reactions to the real good solvents, you know, the ones that eat through nitrile gloves. When I was young I would use gasoline, but it too causes skin reaction. And I don't like the smell afterward, as well it's so darn volatile vapor wise, and heavier then air, so the fire risk is too great.
> When I powder coat parts for the truck, I bake them at 400 degrees to burn off any left over hydro carbons, that seems to be the trick to a good paint job.
> The JB weld failed on a gasoline filler tube repair I did on my previous car, it is incompatible with the ethyl alcohol that is added to our fuel here (10-15%).


We have 10% alcohol here but we can still use 91 or 96 octane without alcohol,  also alcohol is OK for cars used every day but things like Weed Wackers the alcohol soaks up moisture which reacts to the alloy carby and really fouls things up.


----------



## teeleevs (Mar 19, 2021)

Today's work on the Onan opposed twin half scale.  Photo 1 the valves and seats 2 shop made saddle stop 3 valve guide insert 4 pressing in the insert 5 the press 6 cutting the seat 7 drilling the guide. You can check out the Grandchester Model Live Steam Club Inc in our website, or in Australia Chanel 7s Creek to Coast Saturday 20th March.


----------



## gadabout (Mar 20, 2021)

Nice vision of the club on creek to coast, thanks for the heads up , 
Mark


----------



## teeleevs (Mar 21, 2021)

gadabout said:


> Nice vision of the club on creek to coast, thanks for the heads up ,
> Mark


Thanks Mark, they took 2 hours to produce our 5 minutes of fame    see if you can view this link


----------



## gadabout (Mar 21, 2021)

Teeleevs, something wrong with post link
cheers
Mark


----------



## teeleevs (Apr 27, 2021)

Hi all I have not been on for a while, had carpal tunnel operations March 25th, all's well. Photos 1 and 2, drilling the ports, 3, welding the exhaust system 4 and 5, muffler and intake manifold, just tacked in the photos, 6, starter in place. Maybe a trial start soon.
Ted from down under


----------



## teeleevs (Apr 28, 2021)

Just two photos today, the rings are on the pistons, gaskets made, valve springs fitted, even have carby in place, few little jobs to do, will give it some run in on the lathe get the rings to bed in a little.


----------



## teeleevs (May 18, 2021)

After much work the Onan finally kicked in and ran. Some work to do yet, maybe a bought carby might improve things, we had it running on a petrol soaked rag, and on a gas torch.It runs.

thanks for watching Ted from down under


----------



## ignator (May 18, 2021)

That sounds pretty nice.


----------



## the engineer (May 19, 2021)

brilliant  well done


----------



## ShopShoe (May 19, 2021)

That runs very well, and smoothly.

I'm lookig forward to the fully finished version.

Congratulations,

--ShopShoe


----------



## teeleevs (May 19, 2021)

Thanks Guys, it does run smoothly bolted down to a one ton lathe.  I spent the day attending to oil leaks and other problems, perhaps another day or two before we try again, then I need to make the most visible part, the fan cover. 
Thanks for watching 
Ted


----------



## teeleevs (May 31, 2021)

Someone suggested that the way I made up the crankshaft was risky, well sure enough it came back to bight me, after the run & after a few more trial starts the engine got stiff & the flywheel was noticeably out true (photo1) So the Onan looks like this at the moment, (photo 2) We replaced the bigend inner bushes with a hardened steel pins, (photo 3) Rebored the crank webs, pressed the pins in, tack welded after lining up each part, (photo 4) All ready to go back together. (Photo 5)


----------



## AlexS (Jun 29, 2021)

Welding the crank is the wat to go with a pressed crank. Would likely to see it running again!


----------



## teeleevs (Jul 2, 2021)

AlexS said:


> Welding the crank is the wat to go with a pressed crank. Would likely to see it running again!


Thanks AlexS We have had it running again, we started it on the lathe and lets say I will not need to oil the lathe for a while!  Still having trouble with valve sealing, had issues with timing and in the process put a piece of wire through the plug hole, finished up bending the intake valves (when I say bending ? a .001" miss-alignment would cause a bad leak in such a small part) I re-lapped the more serious one but both need more attention.  During the course of trying to get a re-start I finished up with twin carbs on it (Honda weed basher ones)  I have given the Onan a rest and attended to an upgrade of the tractor, replacing the 46 year old Suzuki 2 stroke jeep engine with a brand new Chinese V twin air cooled one, sounds good.
Thanks for watching. Ted from down under.


----------



## teeleevs (Aug 3, 2021)

The latest on the Onan opposed twin in half scale, it runs  The Grandchester Model Live Steam Club Queensland Australia (of which I am a member) a new engineering trophy has been created in honour of 2 very resourceful and respected engineering men, it is my honour to be the first person to win it with my Onan engine. See photo. Apparently I need to work on the video.


----------



## teeleevs (Aug 3, 2021)

try this YouTube video, it is obvious I have had a win over the oil leaks, there was a crankcase pressurisation issue.


----------



## ignator (Aug 3, 2021)

teeleevs said:


> I have had a win over the oil leaks, there was a crankcase pressurisation issue.


You probably know this, but it was a recent lesson to me, I was rebuilding a 2.75HP Lauson engine (USA made in Wisconsin, and now owned by Tecumseh) they used a check valve, which I now know was common so that the crank case operated with negative pressure. It had ball bearings for the mains, and just simple metal shields, and no rubber seals, and never leaked oil. I see this in all engines now, just never realized they did this. I never thought what the PCV was for on my V8 engine I had as a teenager.
I assume you put such a check valve on your engine to fix the oil leak issue.
That engine runs nice!


----------



## gadabout (Aug 4, 2021)

I just rebuilt a Fairmont engine for my brother for his two seater Fairmont , the engine was a single cylinder with hopper style cooling and a radiator on the hopper. Unusual engine with poppet style valves in the carb/manifold!
Had it running nicely just last Thursday.
cheers
Mark


----------



## teeleevs (Aug 4, 2021)

ignator said:


> You probably know this, but it was a recent lesson to me, I was rebuilding a 2.75HP Lauson engine (USA made in Wisconsin, and now owned by Tecumseh) they used a check valve, which I now know was common so that the crank case operated with negative pressure. It had ball bearings for the mains, and just simple metal shields, and no rubber seals, and never leaked oil. I see this in all engines now, just never realized they did this. I never thought what the PCV was for on my V8 engine I had as a teenager.
> I assume you put such a check valve on your engine to fix the oil leak issue.
> That engine runs nice!


Yes Ignator I had too strong a spring in the valve and nowhere for the oil to go.  The PCV valve on a multi cylinder engine actually works differently, it allows a small draw on the crank case at idle and a large amount at revs. My Onan powered welder began to leak at rear main oil seal but I couldn't remove the generator to replace it subsiquent owner ran it out of oil, problem I found out recently on the web if the valve clogs it will cause oil leaks. Single cylinder engine, (also opposed twin and vee twin) have a great amount of crank case volume changes due to piston displacement, I found this out when I cut down a Toyota 6 and made a single, remembered that Brigs and Straten have a valve in the breather, solved the problem. On my model I have used 2 truck compressor silencers for air cleaners and one to separate the oil blown up the breather valve, all working fine,


----------



## teeleevs (Aug 4, 2021)

gadabout said:


> I just rebuilt a Fairmont engine for my brother for his two seater Fairmont , the engine was a single cylinder with hopper style cooling and a radiator on the hopper. Unusual engine with poppet style valves in the carb/manifold!
> Had it running nicely just last Thursday.
> cheers
> Mark


Some interesting engines about, some 2 stroke boat engines run with valves in the manifolds, allows for oil in the sump. Ted


----------



## gadabout (Aug 4, 2021)

Ted, 
The Fairmont in the first post you made , third pic looks exactly like the one my brother has! 
cheers
Mark


----------



## teeleevs (Aug 4, 2021)

gadabout said:


> Ted,
> The Fairmont in the first post you made , third pic looks exactly like the one my brother has!
> cheers
> Mark


Hi Mark, the model, second pic, runs on 7 and a quarter inch track 184mm the engine is a Victa 160cc much modified, it will run either way, has car pointless ignition with 2 wings to activate the magnetic pickup 18 degrees before TDC in either direction.  In operation the engine runs backward to its original direction smoothed out by a 5kg weight flywheel.   Will pull easily 2 wagons loaded with 16 adults and children.


----------



## teeleevs (Aug 4, 2021)

teeleevs said:


> Yes Ignator I had too strong a spring in the valve and nowhere for the oil to go.  The PCV valve on a multi cylinder engine actually works differently, it allows a small draw on the crank case at idle and a large amount at revs. My Onan powered welder began to leak at rear main oil seal but I couldn't remove the generator to replace it subsiquent owner ran it out of oil, problem I found out recently on the web if the valve clogs it will cause oil leaks. Single cylinder engine, (also opposed twin and vee twin) have a great amount of crank case volume changes due to piston displacement, I found this out when I cut down a Toyota 6 and made a single, remembered that Brigs and Straten have a valve in the breather, solved the problem. On my model I have used 2 truck compressor silencers for air cleaners and one to separate the oil blown up the breather valve, all working fine,


Shortened Toyota engine.


----------



## ignator (Aug 4, 2021)

teeleevs said:


> Shortened Toyota engine.


That looks like it took some doing to seal off all the coolant passages, especially in the cylinder head. That's an interesting project to complete.


----------



## AlexS (Aug 5, 2021)

teeleevs said:


> Shortened Toyota engine.



Some people make from single engines multi, but you did the opposite!

Engine runs quit smooth on your video. Congrets for winning the price


----------



## teeleevs (Aug 16, 2021)

Latest on the Onan opposed twin in half scale, have run it several times lately and it is starting better and will almost idle. Some more work, pictures 1-3, a few days ago this was a perfectly good 20lt drum (4 gallon) picked up on the side of the street (thrown out for annual trash pick up by council). Picture 4, making spot weldable nuts for the wire fan safety part. 
Will look better with some paint. Picture 5, the back side, showing twin air filters and oil seperaater with drain back through rear bearing, coil and wires also fuel tubing, both carbies have their own fuel pumps worked by pressure variation in the valve covers.
Ted


----------



## ignator (Aug 16, 2021)

teeleevs said:


> Latest on the Onan opposed twin in half scale, have run it several times lately and it is starting better and will almost idle. Some more work, pictures 1-3, a few days ago this was a perfectly good 20lt drum (4 gallon) picked up on the side of the street (thrown out for annual trash pick up by council). Picture 4, making spot weldable nuts for the wire fan safety part.
> Will look better with some paint. Picture 5, the back side, showing twin air filters and oil seperaater with drain back through rear bearing, coil and wires also fuel tubing, both carbies have their own fuel pumps worked by pressure variation in the valve covers.
> Ted


Your tin work is beautiful. Looks like this project is almost finished.


----------



## teeleevs (Aug 16, 2021)

ignator said:


> Your tin work is beautiful. Looks like this project is almost finished.


Yes but I have a porosity problem with the sump casting, it leaks oil when not in use, not very much but it only holds a cup full. Have to take things apart and seal it with Locktite. I know that the 1920s Buicks had the same problem with the crankcase castings in alloy.
Ted


----------



## ignator (Aug 16, 2021)

teeleevs said:


> Yes but I have a porosity problem with the sump casting, it leaks oil when not in use, not very much but it only holds a cup full. Have to take things apart and seal it with Locktite. I know that the 1920s Buicks had the same problem with the crankcase castings in alloy.
> Ted


I've seen single cylinder engines, like the Lauson I worked on that used a red oxide enamel paint in the interior side to seal iron casting from oil leaks.
Glyptal is a name that comes up for this paint. It's expensive at $50USD/quart.
Hopefully you can get the oil removed so you can seal it. Do you have a favorite solvent to do this? I ask, as I'm curious for any future issues I may have.


----------



## teeleevs (Aug 16, 2021)

ignator said:


> I've seen single cylinder engines, like the Lauson I worked on that used a red oxide enamel paint in the interior side to seal iron casting from oil leaks.
> Glyptal is a name that comes up for this paint. It's expensive at $50USD/quart.
> Hopefully you can get the oil removed so you can seal it. Do you have a favorite solvent to do this? I ask, as I'm curious for any future issues I may have.


I use a product we call Acetone available from hardware's, there is another product the Auto Painter's use to remove grease and finger prints off cars before painting, Wax Off or similar.
Thanks for the questions, 
Ted


----------



## ignator (Sep 1, 2021)

teeleevs said:


> I use a product we call Acetone available from hardware's, there is another product the Auto Painter's use to remove grease and finger prints off cars before painting, Wax Off or similar.
> Thanks for the questions,
> Ted


I use Acetone as well, available in every home construction supply in gallon cans. It will curdle dry paint. Worse I seem to get skin problems on my fingers when using it. And it eats nitrile and latex gloves. Oddly it's sold as fingernail polish remover.
I've used denatured alcohol in recent times for cleaning metal before painting. That worked well getting residual grease and oil off an antique truck chassis.
By now, you probably have the crankcase sealed from oil leaks, and doing finish work on your engine.


----------



## teeleevs (Oct 3, 2021)

An update on the Onan opposed twin in half scale, See it running  After stripping it down and sealing some poor casting issues I still was not happy with starting and idling. Brian Rupnow's figures on cam design would have been very handy if he had uploaded them a couple of weeks earlier.  Armed with DTI I began checking the valve events and was horrified with what I found and it actually ran, suffice it to say I wrote across my scribble paper. " This engine has a better chance of running backwards ." So I reworked the cam shaft, it ran much better but still not happy, it was obvious something was amiss when the heads ran at different temperatures. I removed the linkages from the carbies, wound the idle stops all the way in and started it up, then backing one screw out until I got near similar reading on both heads, refitted the linkages. It then sounded retarded, on checking the ignition timing it was firing at 8 degrees, I shifted the ignition pick-up back to where I originally had it.  Now starting easily, even with a rope and once so far on the starter, but much better with a battery drill. It will idle down to 1200 Rpm and rev out to 4300 not bad but I never want to work it at that revs.
Ted from down under.


----------



## teeleevs (Oct 25, 2021)

More on the Onan opposed twin in half scale, after a lot of fiddling we reworked the manifold and set up single carby, runs and starts much better.  Then we revisited the shop made carby with some cheating, fitting the fuel pump/diafragme block to the side of a block of alloy with my original throttle body on top, it starts much better will even start and run on one cylinder. I've experienced before once your solve one problem it will throw another up at you, now I'm having problems with crankcase vacuum and it's ability to work the fuel pump. 
Ted from down under. 
Picture 1 the bought carby, 2 ĺooks more original, 3 parts needed for the shop made carby, 4 & 5 final carby in place.


----------



## teeleevs (Oct 30, 2021)

Reasons I was not happy with the dual carbys was after only a few minutes running heat transferred to the carbys and petrol began to boil, we have seen this problem in older cars especially in tropical areas.  The balance between the two was very difficult to achieve. I mentioned cheating above but the parts used only supplies the fuel to my throttle body which is fully adjustable and also the main jet advances with the throttle. All works fine now and it will start easily on the starter which doesn't swing it over all that quickly. 
Ted from down under. 
Happily creating swarf.


----------

