# Twin cylinder open crank marine engine



## fourstroke

Hello again

I thought I would share with you my latest efforts, as the title says this is my version of a twin, open crank, marine type engine. It has a 32mm bore and 40mm stroke. I'm going to call this one "The Mariner" as the aluminium for the castings came from my late fathers greenhouse frame who served 12 years in the royal navy
It seemed like a good use for the metal but it has proven to be a bit "chewey" when machining

The patterns were made and the base and cylinders cast in aluminium, the head was cast in brass, it took two attempts to get the head right but then I ran into my first problem. If you look at the picture of the head drawing, it was designed with 5 holding down bolts, a close look at the head pattern and the finished casting will show that when I was in my shop making the pattern, the number of holding down bolts increased to six!!
Normally this wouldn't have been a problem but as I plan to hollow out the head for water cooling then this put one of the studs directly over the exhaust passage and complicated things too much. Also the finish on the casting was far from ideal, fortunately I have had an offer from a member on here, Abby, to make me a new head casting so a new pattern has been made

The first few pics are the patterns in the raw and then painted with high build auto primer, the finished castings are next along with some pics of the cylinder core followed by the drawing of the head showing how it should have been made

The base of the cylinder casting was filed flat and it was clamped to the mill table to make a start on machining. The top was skimmed to level it then it was flipped to take the base to its final thickness. Once the centres for the cylinders were marked on some plywood and lined up the holes for the liners were bored and the top cut to final thickness. The casting was bolted to an angle plate to skim the cylinder bosses, the two on the front are for mounting the carb, the large rectangular one will be the mounting plate for the magneto and the final round one on the end is the water inlet

Enough rambling for one post, enjoy the pics and as always any comments, thoughts or suggestions will be appreciated

Regards

Dougie


----------



## kuhncw

Dougie,

Thanks for posting your progress on  this very interesting engine.  It should be a real chugger with the 32 mm bore.

Could you please post a link to a photo of a full engine like the one you are modeling?

Chuck


----------



## fourstroke

Hi Chuck

This engine is loosley based on the frisco standard engines I saw on the net
I have made mine more freelance than copy but something like this

Regards

Dougie


----------



## kuhncw

Thanks, Dougie.  I've seen a running model Frisco at our NAMES model engineering show.  It is a nice model.

My hat is off to your fellows who make your own patterns and pour your own castings.

I'm looking forward to seeing your build as it progresses.  

Chuck


----------



## Cogsy

Your castings look great and it's obviously too late for any advice, but I have vastly improved the machinability of random aluminium casts by adding around 3% copper by weight to the mix. I have no idea what it does to the rest of the properties of the metal but it does reduce 'chewyness'.


----------



## fourstroke

Hi

The next stage involved machining the base casting. 
The bottom was trued up with a file and belt sander till there was no rocking when it was placed on a flat surface. Clamped to the mill table, first the bearing surfaces were brought to height followed by the pads for the four corner pillars and then the pads where the cam driveshaft bearing and water pump will be fitted
The extension to the rear of the casting is where the gearbox will go and these mounting surfaces were machined as well. The bearing caps were held in the mill vise by the spigots cast in to them and the underside machined to size, these were drilled tapping size for 5BA and the caps were glued to the base while the holes were transfered then tapped. The caps and base were cleaned of glue then fitted together to mark the crankshaft centres  

Now, the next operation was a first for me, I have never machined anything clamped to the lathe cross slide before. There was a lot of measuring, marking and measuring again to get everything lined up. I made a base from some 10mm plate bolted to the cross slide and mounted a couple of box section peices that had been milled to give the correct centre height, the box section and the casting were secured with some home made clamps  as nothing else I had gave me enough clearance.
The casting was lined up against centres in the tailstock and headstock, clamped as tight as I could get it and the first bearing pillar was centred, drilled in stages, then reamed 12mm. This was done as I made a centre drill from 12mm silver steel that would be long enough to reach the last pillar furthest from the chuck and the first bearing hole was used as a steady for the second and consequently the third.
I used a long drill to open up these holes to a tad under 9/16 then a long reamer to finish the holes to size.
At this point I breathed a huge sigh of relief that the whole thing had went witout a hitch. Before the casting was removed the holes were counterbored wilth a 3/4 cutter I made to allow the bronze bearings to clear the taper on the pillars 

Enjoy the pics, more details of the split bearings in the next post

Regards

Dougie


----------



## fourstroke

Most of this work was carried out over the christmas holidays when I had some time off.
There is normally some point in a build when I realise I dont have some material I need and this was it.

 I wanted to make the split bearings but had no bronze bar and with it being the holidays, no chance of getting any. What I did have was a 4"dia bronze bar that I, ahem, aquired, a few years ago. Needs must so I cut two 13mm slices, machined one side of each flat and soldered the two together.
From this I cut a 26mm square section across the mid point to give me the bearing material
Mounted in the four jaw chuck this was drilled and reamed 1/2", then the outside rough turned round.
This was then loctited to a 1/2" shaft, mounted into my collet chuck and the three bearings machined to final size with a parting tool.
 Once split into seperate peices they were mounted on a short spigot to face to final width, the black electrical tape is to hold the halfs together as at this point they had been split
The final picture is the trial fitting of the bearings and the silver steel that will become the crankshaft
As always, comments or advice appreciated

Regards

Dougie


----------



## cwelkie

Beautiful work Dougie!
This will a very nice project from concept through patterns, castings and machining.
Very impressive!
Charlie


----------



## 10K Pete

I really like the bar for the center drill. Great idea! On the reamer; did you 
make the pilot or buy the reamer that way?

This is going to be a great build to follow!

Pete


----------



## fourstroke

Hi Pete
The reamer came fom my favorite tool store, Bill's Tools in Glasgow.
I bought it as it is, I have no idea what it would be used for originally but this store sells lots of second hand tools, frequently ex MOD, and often like this was, unused.

I have had it for a year or two and bought it with no idea what I would do with it till this project came along

Regards

Dougie


----------



## 10K Pete

Thanks Dougie,

The reamer is so perfect for the job I just had to believe you made it. But
it was fate!! I think that's why we collect things; just in case....

Pete


----------



## bmac2

Hi Dougie, Great work. Im looking forward to following along and have my chair pulled up and the kettle on. I hope youre not getting hit with any of the nasty weather Ive seen on the news.


----------



## fourstroke

Hi Bob,
Nice to hear from you again, how is your whippet build coming along?

Like Bob says we have had a lot of rain here lately and December temps of
13 Deg C.  I suffered from a persistent leak in the shed roof that drove me mental, eventually I traced and fixed it

The next stage in this build was the crankshaft, this method may have been described here before but this is how I make all my cranks.

A length of 1/2" silver steel was reduced at one end to 5/16 to take a helical gear salvaged from an earlier abandoned project. Four pieces of 10mm plate were cut, glued together to make  pair of blanks and machined to a finished size for the crank webs, these were clamped to the mill table, drilled and reamed 1/2" for the crankshaft and 10mm for the crankpin. The ends were rounded and the pairs split, each web was machined on the rotary table to cut the clearance of 1.5mm needed for the taper on the bearing pillars and cutouts on the base casting
The next picture shows the "kit" of parts needed to complete the crankshaft

The shaft was set in the bearings on the base and the first web was glued into position with 603 loctite, next, using the centre bearing as a spacer and a flat plate as a base the opposite web was glued at 180 deg fom the first. Leaving these to set for a bit, each matching web from the respective pair had the crankpin glued into position. After a few minutes each web and pin assembly was slid onto the shaft, glued and slid into its final position using a short length of 10mm rod to give the correct spacing for the con rods.

The nearly finished crank is shown next set into the bearings, complete apart from the pins and central parts of the crank still to be cut out.

Finally after letting the loctite set properly the webs were drilled and pinned using 3/32" selloc pins, the central parts of the crank between the webs were cut out with a hacksaw and the ends smoothed in the mill. The finished crank is the last pic, the holes for the pins will be filled and smothed over later.
Regards

Dougie


----------



## bmac2

So far the only tricks the Whippet knows are Sit and stay, living in a box on the shelf. Between my wifes family and my own, almost all the birthdays and anniversaries fall between the end October and the end of January. Toss in Christmas and New Years and I have three months each year of limited shop time. Ive started to get set up to do gear cutting but for now I have to live vicariously through everyone elses work.;D

The crank looks great. With all the reading Ive been doing on gear geometry that little helical on the end gives me a shiver :hDe:. 
Thanks for posting  . . . Bob


----------



## Longboy

This surely is a beefy crank and throws for it's displacement. Will you be going for a low RPM torque cam profile for a marine application? I can't help but wonder if there is a project vessel your engine will power down the road.


----------



## fourstroke

Hi Longboy
I dont know anything about cam profiles for specific aplications, as usual, on this build, I will decide on the lift I want and simply file the cams to a point to give that effect
I know its not scientific but it works. I am hoping for a low revving engine but dont envisage ever putting it into a model boat, sometimes they sink

Regards

Dougie


----------



## maury

FOURSTROKE, a couple of things.

First, Very nicely Done!  The castings look great and it looks like you are modeling castings everywhere it is possible to within reason. This will be a big plus on the final model, and the looks will give the appearance of the original.

Second, it is quite gratifying to me to see there are still a few in the model engine hobby who are willing to take the time and effort to make castings for their models. I commend you on the nice work, keep it up and help teach others to follow in your steps.

maury


----------



## fourstroke

Thanks for your comments Maury, I appreciate it.

So
With the crank made the logical next step was the con rods

I turned the taper on the central part of the rods from 1/2" steel, EN1A leaded, then drilled and tapped the lower end 6BA. A piece of 1/2"x1/8" was drilled centrally and countersunk, these were fluxed, screwed together and silver soldered, the first picture is one of the rods ready to heat. 
Once this cooled it was transfered to the mill to cut the flats for the litte end, clamping the flat bar to the mill table ensured that the flats for the piston pin were paralel to the big end bearings

The bearings were made from 1/2" square bar, the ends were cut with a slot drill to let me solder the 1/4" round bar to the ends to make the brasses look like castings, the two halfs of each were glued together and the stud holes spotted through to the bottom half, these were drilled and tapped 6BA. The blanks were glued square to the conrod and the stud holes spotted through onto the con rod base

The next few pictures show the bearings bolted to the rods and ready to have the big and little ends drilled and reamed. Once this was done the brasses were clamped to a stub of 10mm steel in the lathe to reduce the main body of the bearings to 8mm wide and leave the central round boss a shade under 10mm wide, I used some electrical tape on the 10mm stub to give the bearings something to grip
The last job was to mark the width of the brasses onto the base of the conrod and mill them to match. The rods were then split from the parent bar and the ends of the rods rounded using a pin in the rotary table chuck and turning the rods by hand
A finished rod is the last pic

As always, comments or advice greatly appreciated
Regards
Dougie


----------



## xpylonracer

Pete

I have some very similar reamers, mine were used for finish reaming the kingpin bushes on car steering components and have 2 sets of cutting flutes with a reduced diameter part in between, the width between was the distance between the top and bottom bushes on the part.

Emgee


----------



## 10K Pete

xpylonracer said:


> Pete
> 
> I have some very similar reamers, mine were used for finish reaming the kingpin bushes on car steering components and have 2 sets of cutting flutes with a reduced diameter part in between, the width between was the distance between the top and bottom bushes on the part.
> 
> Emgee



Yep, that application makes sense. I've never owned a reamer like that, but
I have put a home made long dead center in the tail stock with the point
in the center drill of the standard reamer. Worked pretty well though
not quite as rigid as the one piece.

Pete


----------



## kuhncw

Dougie,

Thanks for posting your procedure for making rods.  What is the porous surface you are using for silver brazing?  

Nice work.

Chuck


----------



## fourstroke

Hi Chuck

The porous material is a burner plate from a gas fired commercial fryer, its made of some kind of ceramic.
I salvaged some from a unit I replaced in a Mcdonalds a few years ago. Its good for making ceramic burners for model boilers as it can be cut to shape easily.
Its also good for silver soldering as it reflects the heat and if I need to I can thread thin steel wire through the holes to hold parts in place while they are soldered

Regards

Dougie


----------



## fourstroke

Next, in the grand scheme of things, were the cylinder liners.

I didnt have any cast iron but did have some EN1A leaded steel, I posted a question on this forum and on the model engineer website asking whether this would be a suitable material for liners with alumimium piston and cast iron rings. The replies I got confirmed that this would be ok and a number of builders have used this setup without any problems.
So, the first few pics show the steps I took, the blank was drilled out to 1" dia then bored to a few thou under 32mm, the outside was turned a little under the 35mm bore of the cylinder casting to allow for the JB weld that will be used to seal the liner to the casting. The cylinders were honed to finished size of 32mm. Each liner extends from the base of the casting by 5mm.

Pistons next, simple, right?

Not quite.

On a "normal" IC engine, with an enclosed crank, the lubrication of the little end is usually by splash. In this instance, with an open crank, things get complicated ( well for me at least ).
I posted a couple of questions on this forum and the model engineer website asking how lubrication on this type of engine works for the little end, sadly no one replied with a solution. 
So what I decided to do, and jump in here if my logic is wrong, was, instead of having the gudgeon pin fixed to the piston and free to move in a bush in the little end of the con rod, I have fitted the brass bushes to the piston and will fix the gudgeon pin to the conrod with a grub screw. I copied this from one of my full size vintage engines.
My thinking is this, it will be easier to get some oil into the ends of the gudgeon pin bushes from the oil that is fed into cylinder from the lubricator, rather hoping it would get to the little end via a series of holes drilled through a hollow gudgeon pin which was my other option. 

The next pics are the pistons, some of them are "posed", after the fact, as during the machining the batteries on my camera packed in.
What I did was centre the aluminium bar in the mill vise, drilled and reamed to 5/16". I made a bush 5/16" od x 1/4"id, loctited this into the blank then carried out all the turning of the OD to 003" below bore size, cut the ring grooves, 2 for iron rings above the pin and one for an o ring just below the pin to help collect the oil and feed it into the piston bushes, I transfered this to the mill still attached to the parent bar, set it up square to the pin and cut a little flat across the pin centres, again to help collect oil.

The final pic ( sorry for the quality ) is one of the crank, conrods and pistons all assembled.

Regards

Dougie


----------



## Mechanicboy

fourstroke said:


> On a "normal" IC engine, with an enclosed crank, the lubrication of the little end is usually by splash. In this instance, with an open crank, things get complicated ( well for me at least ).
> I posted a couple of questions on this forum and the model engineer website asking how lubrication on this type of engine works for the little end, sadly no one replied with a solution.
> So what I decided to do, and jump in here if my logic is wrong, was, instead of having the gudgeon pin fixed to the piston and free to move in a bush in the little end of the con rod, I have fitted the brass bushes to the piston and will fix the gudgeon pin to the conrod with a grub screw. I copied this from one of my full size vintage engines.
> My thinking is this, it will be easier to get some oil into the ends of the gudgeon pin bushes from the oil that is fed into cylinder from the lubricator, rather hoping it would get to the little end via a series of holes drilled through a hollow gudgeon pin which was my other option.
> 
> 
> Regards
> 
> Dougie



For a open crank case engine use the needle vavle type oil cup lubricator with sight glass to adjust amount of oil but can give a messy engine if fault adjusted or run with too little oil to wear out engine --> to check oil amount is correct: A little oil smoke from exhaust. 

Wick oil lubricator can give give less messy engine and a little oil smoke out of exhaust pipe. 

My engine with open crank has wick oil lubricator mounted on cylinder who give less messy engine. The wrist pin/little end of connecting rod is lubricated by oil from cylinder who is lubricated by wick oil lubricator. The big end of connecting rod is lubricated with oil can before starting engine, it's no problem for me. You can mount the closed oil cup with wick to give small amount of oil into the big end since your engine is not hi reving engine.


----------



## fourstroke

Thankyou Jens Eirik
Thats good information
Regards
Dougie


----------



## fourstroke

Hi,
Once I assembled the crank into the base I discovered my first problem. I had reduced the rear of the crank to 5/16" for the cam drive gear but hadn't reduced it further for the connection to the gearbox.

The first couple of pics are my solution to this. I made a couple of "jacks" from two M6 nuts and a short length of rod, these were placed between the webs to counteract any force from the turning, the end to be reduced was held in the revolving centre and very light cuts used to reduce the diameter to 3/16"

With this complete I decided to make a start on the gearbox. The base casting was returned to the mill and clearance cut in the rear supports.
 The main body of the gearbox is made from a chunk of brass, two groves were cut along its base to let it sit into the main casting, the centre line was marked and the height of the crankshaft was transfered onto this from the crank end
From this centre the brass was drilled and reamed 1/8" for the drive gear, using the next two gears positioned with a bit of cigarette paper between each one for clearace, the lower gear centre was marked using a point turned on a short piece of 1/8" silver steel, drilled and reamed.

Another piece of brass was silver soldered to the top to bring it up to the required height and the top rounded

Six holes were drilled 1/4" around the edge for bolting bosses that are just short lengths of brass rod drilled through tapping size for 6BA, these were also silver soldered into position. The tops of the bosses were milled level then the top of the gearbox was cut from the base using a slitting saw

More pics of the rest of the assembly in the next post

Regards

Dougie


----------



## fourstroke

The first couple of pictures in this next lot show the main body of the gearbox set up on the rotary table to mill out the inside, once this was  done a small block of brass was silver soldered onto the top. The access hole was milled through and the stud holes finished

The carrier for the two idler gears is made from two pieces of brass and two silver steel pins 1/8" dia. The assembly was silver soldered using tipex to prevent the solder sticking to any of the bearing surfaces.The input and output shafts have been increased to their final size of 3/16".   The bushing is 9/32" od by 3/16" id, a couple of pics of the completed assembly are next, the gears are held on with washers and 1/32" split pins

The gear change lever is made from steel plate with a bush soldered into place to match the gear carrier. I made the detent pin from 1/8" square steel.
 Shown in the picture is how I like to hold little square sections in the lathe using a pin vice, this saves changing chucks for one little job, this was faced and drilled for the pull rod

The compled lever is next, the little brass pieces are rivited and soldered on, the bush at the base has been split to clamp it on to the gear plate.

A few views of the completed gearbox are shown last, sealing bushes have been soft soldered to the ends of the shafts and the selector plate with the locating notches for forward, reverse and neutral fitted.

As always comments or suggestions always welcome

Regards

Dougie


----------



## cwelkie

You make it look so easy Dougie ... a sign of a master!
Very nice gearbox.
Charlie


----------



## fourstroke

As I said in my first post in this thread, the head pattern I made was wrong.
 I'm now at the stage where I need the head casting to fix the position of various other components so I made a new one
This set of pictures show the new head pattern being made and then cast.
 I spray the pattern with high build auto primer and finish it with clear laquer

For this pour, I bought some oil bonded sand, bentomix. I have never used this before but I was well impressed with how easy the patterns came out of the sand and how the finish is improved compared to greensand.
The last few pics show the casting straight out of the sand and then after it has been trimmed and given a going over with a wire brush
Now I just need to figure out how to hold the bloody thing for machining!!

Finally some pics of a switch I replaced in a grill, not engine related you might think but when I stripped it I got four pairs of contacts, each with a little tungsten pad and complete with their own flat spring. I'm sure they will come in usefull at some point
As always, comments or suggestions welcome

Regards

Dougie


----------



## bmac2

Hi Dougie
What can I say that gear box belongs in a gallery. Your silver soldering skills are amazing Im not a member of the _slop on lots and grind club_ but I definitely need more practice. The new head looks great. The finish from that petrobond / bentomix sure looks good.


----------



## fourstroke

Thanks Bob
The secret is tipex or some other correction fluid. 
I paint it wherever I dont want the solder to run and it stops the flow in its tracks.
This works for silver or soft solder.

Dougie


----------



## bmac2

Actually I think my biggest problem is patents in my setup. I get frustrated trying to keep the parts aligned while heating them, practice, practice, practice. Ive got some Correction fluid/Tipex but its getting hard to find most places only carry the correction tape. 
Cant think for the life of me why I never thought to try it with soft solder.:wall:


----------



## fourstroke

Now that I had a decent casting it was time to make a start
The base of the casting was ground smooth to give a level surface
The first pictures show the holes for the head studs being drilled then the top of the bolting bosses being brought to a level height

Next I made a double sided jig to hold the head while it was machined, its just a piece of 1/2" thick flat bar with slots cut in one side to clear the camshaft and tappet pillars, a length of 1" square bar is used as a spacer. The stud holes from the head were transfered to both, drilled through 6BA clearance and countersunk both sides, the head stud holes were tapped 6BA, this is just temporary to hold it to the jig

The head was screwed to the jig right way up to clean up the front face which will eventually have the inlet and exhaust cut into it, then it was flipped over and the lower side faced back, I had to remove quite a bit of brass to get under a lot of slag that had accumulated when it was poured, I reduced it from 21mm to 16mm thick

When I cast the head I included a couple of dimples on the base marking the cylinder centre position, I drilled  and tapped these 6BA 5mm deep, the next pic shows why. I made a couple of ply discs that fit the cylinders tightly, these are screwed to the head and then the cylinder block is fitted to make sure I have enough metal left all round and to check that the head studs will drill and tap wthought fouling anything. This simple set up was used to secure the head while the stud holes were spotted through to the cylinder block.

The next post shows the progress so far
Regards

Dougie


----------



## fourstroke

The progress so far

I couldnt resist having a look at how the engine was shaping up now the head was half done
These pictures show things loosley assembled, I have, at the moment, two options for the flywheel, one in CI and one in brass. They are both 5.5" dia, I am thinking that it might look better with a 6.5" dia flywheel. So at this point I would like to ask for opinions of the members, brass or iron, 5.5" or 6.5"?
 Will a larger flywheel let it run slower?
The engine stands 9" tall and 12" long
Comments welcome

Dougie


----------



## kuhncw

Dougie, your twin cylinder is looking great.  A larger flywheel usually means higher inertia, and that will help the engine run slower.  Brass has a higher density that iron, so large diameter and brass would be the way to go in theory anyhow.

I said "usually" regarding the inertia, because, as you know,  inertia depends on where the material is relative to the center of rotation.

I'm looking forward to hearing your engine run.

Chuck


----------



## fourstroke

Now that the head position was sorted I decided to mark up the location of the camshaft drive gear bearing holes. I used my usual method of meshing the gears with a bit of paper between them for clearance, this time it was .003" thick.
Once the centres were scribed onto the base I clamped up the engine assembly onto an angle plate on my surface table to transfer the marks to the head casting. This done both holes were drilled and reamed 3/16" to trial fit the shaft.
Things might move a little when everything is eventually tightened up so a trick I use to avoid binding is to drill the holes in the base and head a little oversize, then I turn up the bearings proper with a good reamed fit for the shaft but make the part of the bearing that fits in the hole a litte undersize so that I can adjust the shaft to its perfect position with a good free running shaft and minimal bearing backlash then glue the bearings into their holes with epoxy

Next the head was marked up for the valve positions, spark plug and the cutout where the intake elbow will fit. The casting was clamped to the angle plate on its jig and the cutout milled, ( sorry about the shaky pic). Next the mounting faces for the fuel tank brackets were cut and finally the valve seat pockets and the spark plug holes were drilled, milled and tapped

Regards

Dougie


----------



## fourstroke

Next job was to cut the intake and exhaust passages. Again, the casting was set up on an angle plate and bolted to the mill table, the holes were drilled and reamed 3/16".
 Now, here I have a question, the passages will be lined with some 3/16" od x 5/32" id bore tube for reasons that will become aparent later. 
Will that size of inlet and exhaust passage be large enough for this engine? 
Its 32mm x 40mm bore and stroke.
 If anyone has an opinion or experience please say before I go any further.
 My thinking is that the smaller bore will pull air quicker through the carb and intake tubes and help with carburettion.

With all the major holes in the head cut it was time to cut the water spaces. The rotary table was centred on the mill and the casting was centred on each bore in turn and  milled.  Apologies for the quality of the pics. First a slot was cut 10mm wide 2mm deep, next the slot was deepened to 10mm in the middle, 1/4" wide. This slot cuts through both the intake and exhaust passages and all the head stud holes. 

This is where it gets complicated.

The inlet and exhaust will be lined with the brass tube mentioned earlier to seal them from the water, likewise the head stud holes will be sealed with short lengths of brass tube to seal the water passage and prevent leaks

Two brass discs were turned to a close fit in the head, parted off and marked up to be filed where the two  met in the head casting. A bit of carefull filing got them both to size ready to be soldered into the head

So, before I solder everything together, has anyone anything to add regarding the diameter of the intake and exhaust passages?

Regards

Dougie


----------



## xpylonracer

Hi Dougie, like many others I have been following your excellent build article and must compliment you for your design and engineering abilities with even casting your own parts.
With reference to the port sizes the inlet pipe does seem small but as you say this will encourage the charge to speed up, because of the envisaged length there is likely to always be some mixture ready and waiting in the intake passage to pass the inlet valve.
I have searched the article again but can't see any reference to which fuel you intend to use, you do however state spark  for the plug, what fuel will you be using ?

Emgee


----------



## fourstroke

Hi Emgee
thanks for the reply. I intend to use uleaded fuel or perhaps colemans fuel
At the moment I am thinking that I will increase the port sizes from 3/16" od to 7/32" od. Once the ports are soldered into place and the covers fitted to the water passages it will be impossible to increase the diameter but if needed I could decrease the diameter by sleeving another tube into the first
Regards
Dougie


----------



## WSMkid

Fourstroke,
This is my first contribution to the forum in probably 3 years but I spend about an hour a day on the site. 

 About your intake runners. When you mentioned your concern about there size I automatically thought about the old (Buick?) nail head big blocks. I have no personal experience but my buddy talks about them all the time. I digress. They had super small exhaust valves (comparatively) and produced fantastic low end toque. 
With this being said I would think that if anything your small runners will help keep your idle low and smooth and for a running model (I have not seen a mention of putting it to work) this would be ideal. 
I love the water space design in the head. I had never thought of doing anything like that. 
I will be following along with the rest of the build like most others. 
Fantastic work,
 GJ


----------



## fourstroke

Well I decided to go ahead and increase the size of the ports, the next size up of brass tube I had was 1/4" od. So the casting was set up and the passages drilled and reamed
My thinking is this, if I need to reduce the size of the passages I can just slide in a smaller diameter tube, but there is no way of increasing the size once it is all soldered up.

The first couple of pics show the head with pieces of brass tube set up ready to be fluxed and soldered. Because I increased the size of tube I had to make a little undercut under each one to provide clearance for the water to pass
The next two pics show the end result after the tubes are soldered and the flux cleaned off.

The ledge for the two rings to sit on was fluxed and both of them placed into position and solder run around the inner and outer edge the next pic shows the result. Finally the casting was clamped to the mill and the base skimmed, a nice ring of solder is just visible in the pics

The final pic shows the casting being checked for leaks, I filled the water space using a small syringe and have set it on some absorbent paper to see if any water makes it way out, so far, so good

Thanks to all who helped with advice regarding the ports

Off now to shout at the tv while Scotland (probably) suffer another glorious defeat to Wales at the rugby

Regards

Dougie


----------



## Brian Rupnow

Very nice build.--I am following with interest.---Brian


----------



## fourstroke

Well. I was right about the rugby

Leaving the head filled with water overnight showed there were no leaks through the soldered joints
The next stage was to drill and ream the stud holes 5/32" for the brass sleeves. Little lengths of tube were cut and I decided that rather than solder them into place and risk upseting the previous joints I would glue them in place with loctite
The first two pics show the tubes in place. The casting was left in the warm for a couple of hours before the excess was trimmed. The base was sanded smooth and the tops of the bolting bosses were filed flat. I also drilled and tapped the water outlet hole
The final pic in this set shows the head set up with a litte length of 1/4" copper tube screwed into the outlet to provide a little "head" of water while the last leak test takes place

Regards

Dougie


----------



## kuhncw

Dougie,

Nice work on the cylinder head and the water cooling passages. 

Did you silver solder (silver braze) the joints or did you use soft solder?

Chuck


----------



## fourstroke

Hi Chuck, Thanks for your comments
Everything was soft soldered, there wasnt much chance of anything moving or slipping during the various  operations so I didnt see the benefit of silver solder and it made things much simpler
Regards
Dougie


----------



## fourstroke

With the head water passages complete I now needed to set the positions of the upper and lower cam drive shaft bush

The lower hole in the base was made a little oversize for the bush and the position set by meshing the two gears with some cigarette paper between, to give some clearance, and glueing the bush into its hole. Once the glue set the top bearings were positioned, covered with tipex to stop the solder flowing where I didn't want it to go, and soft soldered into place.

The casting was then mounted onto the jig and the centre height of the drive gear transfered onto the uprights where the camshaft will be supported. After squaring everything up the two gears were meshed, again with some paper between, and the position of the first bearing hole marked. The first hole was centred, drilled and reamed 10mm. This might seem a bit large for a 3/16" camshaft but they need to be this size to allow the cams, which will be fixed to the shaft, to pass through.

A home made centre drill made from a piece of 10mm silver steel was used to transfer the centre onto the mid upright, this was again drilled and reamed 10mm. The final upright, the one furthest from the drive gears, just needed a 3/16" hole to support the shaft, once it was centered the same way as the others it was drilled 5/32" using a long worm drill. Later the casting will be upended and the hole reamed to 3/16"
The casting was re positioned to bring the rocker arm pillars under the mill and the holes for the rocker pivots drilled 5/32"

More pics in the next post

Any comments, suggestions or ideas welcome

regards 

Dougie


----------



## fourstroke

I now made a start on the eccentric drive that will power the water pump.

 I decided on a stroke of 3/8" so set some brass in the three jaw chuck with a packing piece under one of the jaws to throw the bar off centre and give me the offset I needed. Once the hole was drilled and reamed 3/16" the packing was removed and the drive turned to 14mm. A piece of bronze was bored to match the drive and parted off, this was filed to shape and the two parts are shown in the third pic in this series

The last three pics show the various parts assembled to see how things were looking and to check everything rotated freely

Regards

Dougie


----------



## deverett

fourstroke said:


> Off now to shout at the tv while Scotland (probably) suffer another glorious defeat to Wales at the rugby
> 
> Regards
> 
> Dougie



And then Ireland!

By the way, Good work on the engine.

Dave
The Emerald Isle


----------



## fourstroke

Yes, probably.
But, as celts, we both know there's only one match that needs to be won to numb the pain of all other defeats, we didn't manage it this time but good luck on the 27th
Regards
Dougie


----------



## bmac2

OK. Im going to assume you guys are talking about the Six Nations Championship? I had to do a quick search on the _infomercial super highway_ and all I can say is [email protected] CR#P good thing its on TV. The tickets for the England vs Wales match on the 12 are _starting _at £550!  Thats like $1061 Canadian! 
Oh ya . . . . Dougie, the engine is looking great Thm:. . . . . I got to go splash some cold water on my head . . . . . £550!


----------



## deverett

bmac2 said:


> OK. Im going to assume you guys are talking about the Six Nations Championship? I had to do a quick search on the _infomercial super highway_ and all I can say is [email protected] CR#P good thing its on TV. The tickets for the England vs Wales match on the 12 are _starting _at £550!  Thats like $1061 Canadian!
> Oh ya . . . . Dougie, the engine is looking great Thm:. . . . . I got to go splash some cold water on my head . . . . . £550!



You're right - a bit expensive for a ticket, but they take their rugby seriously over there.

Dave
The Emerald Isle


----------



## fourstroke

Hi
I decided that next I would complete the water pump
This series of pics show the various pieces being soldered together, silver solder for the first parts and then soft solder for the final assembly. Its a simple two ball valve, the 1/4" street elbow in the bottom for the inlet had a perfect size hole for a 3/16" stainless ball and all it took was a clout with a hammer to form the seat

The base was first with a high melting point solder along with the right angled outlet on the valve section. The main body was turned to size and then soldered with some easyflo to the base section
Lastly the valve section was joined to the body with soft solder, the pics show the parts held together with steel wire on the perforated board
A screwed plug with a square head was made to seal the top opening and the rear of the barrel sealed with a brass plug

The final pics show things set into position to check rotation 

Regards

Dougie


----------



## fourstroke

With things on the base casting pretty much complete, I decided to make the rockers

First the head casting was bolted to the mill table and the rocker posts trimmed each side to square them up. Next the basic shape of the rockers was marked out onto some 3mm steel plate, the pivot hole was drilled 15/64" and the lower edges cut and filed to shape.The top edge was left flat to give me a level surface to sit the rocker on while it was silver soldered together

At this stage the tips were case hardened, once that was complete the pivot hole was reamed 1/4" and two 1/4" pivots were drilled and reamed 3/16". Two slices of 1/4" steel were drilled and tapped 6BA for the adjusting screws.

The next pic shows the kit of parts to make two rockers, followed by one set tippexed, fluxed and held to the perforated board with wire to silver solder everything together.

The last pic shows two of the four rockers complete apart from the brass bushes in the pivots to bring the internal size to 5/32".
Now they just need a good clean with a wire brush

Regards

Dougie


----------



## fourstroke

As I mentioned in a post in my last engine build, I can get carried away thinking about so many things to add to a project, that it never gets finished. I fall very much on the " its not the destination, its the journey", side of the fence.

And so it has been with this engine, I spent days dreaming up a flyball governor, position, mounting etc, a nice addition but not what I need to be doing

With that in mind I am trying to concentrate on things that the engine cant do without and with this design being a 180 deg opposed crank it needs a distributor. I started last Saturday thinking it would take the weekend, three prototypes later I think I got the final design finished tonight

The first pic shows the backplate/mounting plate on the left along with the register for the distributor body on the right, both of these are made from tufnol, as is the rest of the unit. The centre holes are drilled and tapped 6BA at this point to get the centres lined up while the two were glued together with araldite
Once this set the centre hole was drilled 5/32" and the part mounted on the camshaft while the holes for the securing bolts were drilled and tapped. The centre hole was opened up to 11/64" for clearance

Next is a pic of the beginning of the body, a piece of tufnol was held on a mandrel while the body was turned to size, 14mm. It was held in the three jaw and bored to internal size of 11mm to match the register. The next pic shows the three main components, mount, rotor and body. The body was set in the rotary table while the holes for the terminals were drilled at 90deg apart

The (third attempt) at the rotor is shown with its terminals in place, the screws are 10BA, they meet internally to make electrical contact and carry the spark from the centre to the edge, the following pic shows the body with two 4mm tufnol inserts to hold the 10BA screws for the spark plug leads

The last pics show the assembly on the engine, to set it up I screwed in each spark plug terminal in turn till I got contiuity on my multimeter from the lead to the centre 8BA terminal. I then backed each one off half a turn to set the gap and locked the terminals in position, the centre screw on the rotor is not countersunk competely to let it stand very slightly proud of the rotor. The rotor is held to the camshaft by a 10BA grub screw.

As always, enjoy
Comments, suggestions or advice welcome
Dougie


----------



## fourstroke

Next in the grand scheme of things was the dummy magneto that holds the hall sensor and the rotor fitted with two magnets to supply the ignition

The first couple of pics show the basic body shape cut from a block of aluminium, at this point its  a little overwidth and still has the top to be rounded, the following two pics show the body at final width of 17mm and the top rounded off, the shaft will be 1/8" dia and runs in some brass bearings made from k&s tubing

After checking the angle of the timing chain between the camshaft and the magneto the head casting was set up on the mill table to cut the slot for the chain to run through. The rotor was turned from brass, set up in the rotary table and the two holes for the 2mm dia magnets were drilled. A bracket for the magneto to sit on was silver soldered from three peices of 1/16" steel, slots were cut into it to give me some adjustment horizontaly and vertically
Everything was screwed into place to check clearance and slack on the chain

Finally there are a couple of pics of the magneto with all the internals fitted, the brass lever will hold the hall sensor in place above the rotor and can pivot to advance or retard the ignition

Regards

Dougie


----------



## fourstroke

I was toying with the idea of making an "automatic" type of carb for this engine, along the lines of the one I made for the last build. But, I was having a bit of difficulty fitting the designs I had in the space I wanted. So, after some thought, and advice from seadragonfoundry on here I decided just to go with a "standard" needle valve carb.

The first few pics show the start of the upper  manifold that will split the intake to both cylinders. It started as a short length of 1/2" sq brass, a flat was filed onto one corner and a small hole drilled diagonally through, this was superglued to the head casting and the hole spotted through and opened up to tapping size for 6BA.
The block was held in the vice and thefront of the hole opened up to 3/16" for a spigot that will be silver soldered in later. The transfer holes for the fuel were marked on the sides and base then drilled 3/16". The top was rounded on the belt sander and polished smooth.

After a couple of failed attempts to build up the main body I finally settled on a brass pipe elbow that had the right size and perfect flare. The unwanted hose barb and threaded portion were cut off and a couple of filler pieces turned and fitted to the insides then silver soldered into place and drilled 7/32".

A small groove was cut on one side of the front flare to take a length of 3/16" brass drilled and tapped 8BA, this  was silver soldered into place and will hold the shutter to the body. The jet is shown next, the small thread is 6BA and the large is 3/16 x 40 for the fuel union
The next pic shows the main body with the jet and needle valve in place and the front has been opened up with a home made taper D bit. 
There a couple of pics missing where my camera battery went flat, this was when the upper manifold and body were joined by a length of 5/16" brass tube and a backplate was shaped and soft soldered to the back of the body.

Finally there are some pics of the completed carb assembly and some of it fitted to the engine

Regards

Dougie


----------



## bmac2

Hi Dougie
The engine looks to be coming along great. Thats a very cool looking carb, matches the feel of the engine perfectly. 
Thanks for posting


----------



## fourstroke

With the carb sorted I moved to the exhaust

The first pic shows a piece of 12 x 3mm stainless steel marked up with the shape of the flanges and the holes for the exhaust and holding bolts drilled. I shaped the outer edges of the flange on the sander and opened up the exhaust holes to 5/16", this piece was then centred onto the head casting and superglued in place while the holes for the studs were drilled and then tapped 6BA
Two pieces of 5/16" stainless tube were bent into right angles and while the flanges were still in one peice I sanded the longer ends till they met in the middle with a close fit. A scrap piece of steel was drilled and tapped 6BA to match the hole centres of the flanges, these were then split into seperate pieces and rounded off as I wouldnt be able to get to the inside faces with my sander once they were soldered, the next pic shows the tubes held in the flanges while the centre section was silver soldered. This sub assembly was then removed from the scrap steel and the flanges silver soldered to the tubes

The vertical section is made from 10mm stainless tube, one end was ground to a close fit over the two previous sections and the centre of the two pipes ground out also. The twin section was screwed into position on the engine and the vertical section held in place with some wire, this joint was then tipexed, fluxed and silver soldered into place once I was happy it was straight and vertical

Regards

Dougie


----------



## fourstroke

Now I needed a fuel tank.

I didnt have any tube of a suitable size so I rolled my own
I started with a rectangle of brass long enough to give me a finished diameter of 30mm. The first pic shows the flat brass sheet and the second shows the tube after rolling. The overlap was trimmed with a dremel and a cutoff disc, the ends were annealed and formed over a steel bar to round the long seam.

The join was tippexed and soft soldered along its length. A filler neck was turned and threaded 3/8" x 32 along with a flange for the outlet, the next pic shows the filler, outlet flange and two lugs for mounting the tanh to the rear of the engine soft soldered into place, the ends have also had brass discs soldered into place
The last pics in this set show the tank in position on the rear of the engine

Regards

Dougie


----------



## fourstroke

This set of pics show the little fuel shutoff valve I made along with some views of the engine with all the latest additions fitted

The body is made from 6mm brass rod. A small piece was turned down to 7/32" and threaded to match the fuel outlet flange, a cross hole was drilled into another length of brass and silver soldered into place

The body was cut to 30mm overall length, drilled 2mm through and then opened up to 5/32" with a slot drill 20mm deep, this gave me a flat face for the valve spindle to seat onto, The inside was tapped 3/16 " x 40, 14mm deep
The next pic shows the various components of the assembly. The body, glands and union nuts all from brass and the spindle and handle from stainless steel followed by the parts all assembled
Lastly are some views of the progress

Regards

Dougie


----------



## kuhncw

Hi Dougie,

Your engine is looking great.  I especially like your exhaust manifold and stack. 

How will you control engine speed?  I'm guessing the plate and lever on your carb is the choke.

I'm certainly looking forward to hearing it run.

Chuck


----------



## fourstroke

Thanks Chuck

I'm hoping to use the shutter on the carb to set the speed, I dont know how well this will work but I hope it wont take much fiddling between needle valve and shutter to get it running at a steady beat
I'm aiming for a slow speed set up, if you have any advice then let me know

Regards

Dougie


----------



## kuhncw

Hi Dougie,

Your carb setup is like the mixers I use on hit & miss engines where rpm is controlled by the governor latch out.  I can't say your design won't work, but I'd think it would be very touchy to adjust in order to hold rpm and keep the mixture correct.  

I think you'd need a throttle of some sort, maybe like the barrel throttles used in simple model airplane carbs.  George Britnell has designed and built throttling carbs for his multi cylinder engines.  Perhaps George will chime in on this.  

Chuck


----------



## fourstroke

A little more progress

I needed to come up with a system of getting oil to the big ends, I had left very little room between the nuts holding the bearings together and the vertical part of the con rod
The solution I came up with after a lot of thought is shown in the first few pics. Its a length of 5/32" brass tube reduced to 1/16". I drilled a hole 1/16" dia as close to the base of the rod as possible, through the steel part and a little way into the top half of the bearing. This hole was then drilled at an angle through to the bearing surface using a 0.6mm drill

The  oiler will be held to the conrod with a 1/32" rivet through the tang filed at the top, I will fix it with loctite on final assembly

The last couple of pics show the main bearings with their oil cups fitted

Not very exciting but every little bit helps

Regards

Dougie


----------



## kuhncw

Hi Dougie,

Your oiling system looks good.  That should take care of it.

Chuck


----------



## swst

Your Cast Aluminium Foundation :bow::bow::bow:


----------

