# ETW Sealion



## Weldsol (Jun 16, 2021)

Hi I have not posted this as a blow by blow way of building this engine, just done the photo's to give some idea

Jan, 2020 I decided to go for the sealion but with no castings, so the drawings and ETW's notes from 1959 Model Engineer mag's were purchased from Hemingways and upon arrival started to do a breakdown on CAD to see what metal would need removing from bar stock to achieve each part ready to make a start on machining.

Then the lockdown started so I had to self isolate in my workshop (that is what I told my wife Ha Ha

First was the crankcase I ordered a 6" length of 3 1/2" square, faced the ends and put some datum lines on.
Next was the crank machined from EN16t
Then bearing endplates
Next was the cylinder head
Cam plate
Cam jig
Cam
Rockers (that's another story )
Carb

All the machining was using my lathe or mill.
I will put some more pic's up when I have some more time
Paul
Just remember If it cant be fixed with a hammer it must be an electrical fault


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## Basil (Jun 16, 2021)

Beautiful work! I am building a Seal Major 30cc. Very similar parts. Getting courage to tackle the cam. More pictures please


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## Weldsol (Jun 16, 2021)

more on there way

Paul


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## IC-man (Jun 17, 2021)

Weldsol said:


> Hi I have not posted this as a blow by blow way of building this engine, just done the photo's to give some idea
> 
> Jan, 2020 I decided to go for the sealion but with no castings, so the drawings and ETW's notes from 1959 Model Engineer mag's were purchased from Hemingways and upon arrival started to do a breakdown on CAD to see what metal would need removing from bar stock to achieve each part ready to make a start on machining.
> 
> ...


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## IC-man (Jun 17, 2021)

Hi weldsol,
Very interested in your work, I started making the sealion from castings some 20 years ago and finally finished it about 18 months ago and got it running.
The castings were rubbish but I persevered and managed to finish with modification to overcome the poor quality of the castings.
Recently I've been thinking I'd like build another from bar stock so would be very  interested in any info you can give.
Thanks so far.
Where are located?
Graham


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## Weldsol (Jun 17, 2021)

IC-man said:


> Hi weldsol,
> Very interested in your work, I started making the sealion from castings some 20 years ago and finally finished it about 18 months ago and got it running.
> The castings were rubbish but I persevered and managed to finish with modification to overcome the poor quality of the castings.
> Recently I've been thinking I'd like build another from bar stock so would be very  interested in any info you can give.
> ...


Hi Graham I'm in Hertfordshire UK


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## PeterDRG (Jun 17, 2021)

You've just reminded me that I've a Triple Expansion to finish :-(


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## a41capt (Jun 17, 2021)

Beautiful work Paul, looking forward to more pics!

John W


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## Weldsol (Jun 17, 2021)

Hi John did you see the other posts ETW2 &ETW3 I did them like that as I could only put up 10 pics at a time  on reflection I suppose I could have added to this post as replies and kept as one post ?

Paul


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## a41capt (Jun 17, 2021)

Weldsol said:


> Hi John did you see the other posts ETW2 &ETW3 I did them like that as I could only put up 10 pics at a time  on reflection I suppose I could have added to this post as replies and kept as one post ?
> 
> Paul


Thanks Paul, I’ll look for those other posts!


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## Weldsol (Jun 18, 2021)

Here are a few more pics.
The cam follower one shows a problem I had with the one as on the drawing.
the cam contact was hitting the follower just (and I mean just) above the pad which I considered to be a problem so a fresh set was made with the pad going right up to the boss.
The other issue I had was because I was following ETW's notes and drawings and using BA threads, this was fine until I made the conrods which you drill and tap 5BA and fix the cap prior to machining the big end, I had used 5BA bolts during the machining op's.
Then I tried to source the 5BA socket head cap screws.
Everybody that listed them couldn't supply them then you find out the last known place that had them was in Australia and that was back in 1987 but I went to there site and guess what you got it "unable to supply this item"
So now I was stuck I couldn't go to 3mm cap heads 4BA was to big as the thread would just cut through to the big end.
So I did some checking on BA cap head dimensions and came up with the following :-

The head size on 4BA is only a few thou bigger
The Allen key size is the same
You cannot turn down a 4BA & re-thread 5BA as the core diameter on a 4BA is just bigger than a 5BA so you are left with some 4BA threads .

The solution I used was to get some 1 1/2" long 4BA cap head bolts which gave me approx, 3/4" plain shank to turn down to 5BA o.d. and then thread them

Paul


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## IC-man (Jun 18, 2021)

Hi Paul,
Nice work. How did you profile the outer block shape?
You are obviously trying to replicate ETW build. I was thinking of doing away with the gear drive to the cam and using belt and pulleys. I also had real problems with the original distributor so triggered the ignition from 2 magnets on the crank pulley to hall switch.
Graham


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## Weldsol (Jun 18, 2021)

Hi Graham
The out profile I had to mark out where the ribs were and the mounting lugs.
then mark out the profile on one end then it was onto the mill with a rotary table and tailstock and then roughed it all down with a 1/4" ripper endmill  then for the last 20 so thou used a 3 flute endmill to finish then blend with a fine file.
Mine is not a true ETW build as I have changed a few things mainly on the top end such as pressure oil feed to the cam bearings and change the top cover, also changed his exhaust / inlet manifold.
I will be using gear drive for the cam and oil & water pump, for the ignition will probably go hall effect sensor inside distributor cap.

You never said where you were ?
Paul


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## IC-man (Jun 19, 2021)

Weldsol said:


> Hi Graham
> The out profile I had to mark out where the ribs were and the mounting lugs.
> then mark out the profile on one end then it was onto the mill with a rotary table and tailstock and then roughed it all down with a 1/4" ripper endmill  then for the last 20 so thou used a 3 flute endmill to finish then blend with a fine file.
> Mine is not a true ETW build as I have changed a few things mainly on the top end such as pressure oil feed to the cam bearings and change the top cover, also changed his exhaust / inlet manifold.
> ...


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## IC-man (Jun 19, 2021)

Hi Paul,
I'm in Kent, personally  I would think very carefully about putting the hall device in the distributor, they hate emf. And I speak from experience. That's why I timed the spark from the crank.
Others might disagree.
Anyway fine progress can't wait to see it running.
Graham


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## Steamchick (Jun 19, 2021)

Many production cars use crank mounted sensors, because there is no drive to affect the accuracy of timing. With electronic ignition, the advance timing is done electronically, the can give up to 5 degrees more advance than points and mechanical advance mechanisms. The electronics can also use piezo sensors (like microphones) to sense and retard the engine should any knock occur (e.g. For poorer fuels than manufacturers specify. You hope the garage is giving you the octane on the label, but can never be sure without testing.).
But modern cars use individual plug mounted coils,  so individual cylinders can have slightly different timing as throttle and load conditions vary, and should a cylinder be knocking for any strange reason. Electronic triggering of multiple coils is now cheaper than distributors, but plug mounted coils are unlikely to appear on models for reasons of authenticity, and size.
K2


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## Steamchick (Jun 19, 2021)

Many production cars use crank mounted sensors, because there is no drive to affect the accuracy of timing. With electronic ignition, the advance timing is done electronically, the can give up to 5 degrees more advance than points and mechanical advance mechanisms. The electronics can also use piezo sensors (like microphones) to sense and retard the engine should any knock occur (e.g. For poorer fuels than manufacturers specify. You hope the garage is giving you the octane on the label, but can never be sure without testing.).
But modern cars use individual plug mounted coils,  so individual cylinders can have slightly different timing as throttle and load conditions vary, and should a cylinder be knocking for any strange reason. Electronic triggering of multiple coils is now cheaper than distributors, but plug mounted coils are unlikely to appear on models for reasons of authenticity, and size.
K2


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## Weldsol (Jun 19, 2021)

Re the ignition side I may go to these people or even try ETW's points & coil as this engine will never be driving anything 




__





						Home of MiniMag Co.
					





					minimagneto.co.uk
				



I'm not sure what way to go yet as it will be a fair bit of time before I have to make that decision 

Paul


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## IC-man (Jun 20, 2021)

Hi Paul,
I tried standard points and coil ( and I believe many of these engines have worked fine) but I had lots of problems stopping arcing inside the dizzy cap so tried all sorts of fixes even 2 x twin Honda coils using "lost spark" finally getting it running with 2 x magnets on the crank to a Hall device to a CDi.
Also tried buzz box with no joy.
Thanks again for the pics.
Graham


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## Eccentric (Jun 23, 2021)

Paul,

Great work,  I have the Sealion on my "to build" list; I consider it the most refined ETW's designs.  I am now building his Wallaby borrowing many of the construction methods from the Sealion--such as main ball bearings in bearing holders and the arrangement of the timing case. 

Have you decided how you are going to fabricate the main center bearing?  Will you use ETW's design of 7/8" leaded bronze rod? I am still noodling on this one.

Good luck, I will be closely watching your progress.


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## Weldsol (Jun 23, 2021)

Eccentric said:


> Paul,
> 
> Great work,  I have the Sealion on my "to build" list; I consider it the most refined ETW's designs.  I am now building his Wallaby borrowing many of the construction methods from the Sealion--such as main ball bearings in bearing holders and the arrangement of the timing case.
> 
> ...


Hi there
Yes the centre was completed partially when the crankcase was machined ( the bearing cap ) and the bearing was made after the crank was finished and is now installed with the crank.

Paul


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## Weldsol (Jun 23, 2021)

IC-man said:


> Hi Paul,
> I tried standard points and coil ( and I believe many of these engines have worked fine) but I had lots of problems stopping arcing inside the dizzy cap so tried all sorts of fixes even 2 x twin Honda coils using "lost spark" finally getting it running with 2 x magnets on the crank to a Hall device to a CDi.
> Also tried buzz box with no joy.
> Thanks again for the pics.
> Graham


Hi Graham I sent you a private message
Paul


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## Weldsol (Jun 25, 2021)

Eccentric said:


> Paul,
> 
> Great work,  I have the Sealion on my "to build" list; I consider it the most refined ETW's designs.  I am now building his Wallaby borrowing many of the construction methods from the Sealion--such as main ball bearings in bearing holders and the arrangement of the timing case.
> 
> ...


Hi there 
on re-reading your post here is the description on how I made my centre bearing.
The first thing I did was to make a plug gauge to the diameter of the centre bearing of the crank,
Then another one to fit the OD (between the flanges) of the crankcase and bearing cap.
Next was to mark out the centre of the bronze (leaded) bar then onto the mill and drill and tap & counter bore for two 4mm cap head screws ( the clearance for the screws are opened up after slitting ) Note allow enough material to allow bearing width and screw heads) then slit down the centreline then saw the top half through just passed where the cap heads are. Now clean up the faces and tin with soft solder   (not quite up to the threaded holes) 

Now you can bolt the two halves together, heat the bar until the solder runs, tightening the cap heads as you heat I also used an old toolmakers clamp on the end  just to make sure it was pulling down equal.
Now you can chuck in the lathe, I did the bore first (using the plug gauge) , then roughed out the OD between the flanges, keeping the outer flange a bit thicker as this can be reduced after getting the OD to size using a mike and the gauge for the OD as a reference.
For sizing the width between the flanges I used the bearing cap and a feeler gauge to give me my running clearance. Now face back the front flange to give you the required thickness (distance to outer edges taken from the crank) I put a groove behind the rear flange so that I could measure the total width
Now you can put in the bore the oil groove then part off .
I know this sounds long winded but after doing the bearings for my Shay loco and having the two halves separate during machining I went this route with no further issues

Paul


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## Eccentric (Jun 25, 2021)

Thanks for your detailed explaination Paul, it makes good sense.  The use of solder is interesting,  I understand the need to insure the two halves remain secure in the proper orientation while turning the ID and OD of the bearing. I have not made my crankshaft yet, but will keep your method in mind for when I am ready to fabricate my center bearing.


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## Weldsol (Sep 29, 2021)

Finally found some time to get on with a bit more of the engine.

The oil trough I machined from 1/2" flat plate by bolting uprights each end and setting it on the mill between centres using my rotary table and tailstock and  ball nose milling cutter.

The oil and water pumps I carved from round bronze bar using the lathe and mill, the sockets for the gears were done on the lathe using a three jaw chuck held in a four jaw chuck so I could set over for the gear centres.
Note the P.C.D. on the oil pump gears is 1/4" and 5/16" for the water pump gears.

The drive for the pumps is by a skew gear driven by the crank. and the cross shaft is grooved to drive the oil pump

The distributor cap was a pig the setup for drilling due to its shape and the hole centres were pre marked in the injection moulding and were way out for the 90 deg, between each one, so took a bit of head scratching but got there in the end.
I'm going the contact breaker points route for the ignition, I say that but all the points will do is trigger a processer so will only have 10 milliamps across them.
The rocker for the points was made from Peek and brass.
Then the clips for holding the distributor cap. I contacted a clock repairing friend who was able to supply me with some clock spring material and once made soft with a bit of heat were easy to shape then a bit more heat and a quenched.

Paul


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## Steamchick (Oct 2, 2021)

EXCELLENT WORK! Well done!
K2


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## johnnyo (Oct 11, 2021)

Hi Paul
May I ask where you sourced the skew gears, or if you machined them could you touch on that briefly. Im curious as to how I would cut these. 
Thanks
John


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## Weldsol (Oct 12, 2021)

johnnyo said:


> Hi Paul
> May I ask where you sourced the skew gears, or if you machined them could you touch on that briefly. Im curious as to how I would cut these.
> Thanks
> John


Hi John
I got the pump drive gears from Hemingway

Model Engineering Kits and Engineering models from Hemingway Kits 

Paul


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## Weldsol (Oct 16, 2021)

Started to do the final assembly two weeks ago then the calamity happened.

When I finished the block and the liners were installed I lapped the face of the block, I also lapped the face of the cylinder head as I was not going to use a gasket just a smear of Hylomar universal.( this was around 3 - 4 months ago)
I had trial fitted the head to the block when doing the centres for the cam drive gears and drilling  the front plate for the cam bearing so I knew everything  was in line and the gear mesh was correct.
Then 2 weeks ago I had to move some stuff in the workshop, turned around with a box I was carrying only to clip the cylinder head and knock it off the surface plate onto the bench so maybe a 100mm drop.
When I had got rid of the box I was carrying I picked up the head only to find it had taken a hit on the lapped face.
It didn't look that bad maybe a 1/4" mark and it didn't look very deep more of a scratch BUT it was where it was right across the narrow part where it would have to seal the centre cylinders.
After a lot of very strong words and thinking how to overcome this I decided to re lap the face which I did, then all the knock on effects started to add up as I had taken  3 1/2 thou off to clear the damage so the cam bushed no longer fitted and the gears no longer fitted.
So I decided to do a PTFE gasket I managed to find a local company that produce different thicknesses and spoke to a very nice person and asked if they did 0.1 mm thick sheet or tape, he could not get his head around that it was for a small engine and I only needed a piece 150mm x 50mm but after explaining things to him he ok I will send you a free sample ( which turned out to be 300mm x 300mmm) which was a result.
As soon as it arrived it took me around 1hr to produce and fit the gasket and once fully tightened the head the cam bush slid in and the gears fitted and were back in mesh as if nothing had happened.
So it goes to show that **** happens but it can be cleaned up

Paul


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## Eccentric (Oct 16, 2021)

Glad to hear it turned out OK and you did not have to remake any components.


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## Weldsol (Oct 17, 2021)

Eccentric said:


> Glad to hear it turned out OK and you did not have to remake any components.


No it all went back together as it was before the incident and everything is now pushed to the back of the surface plate away from stray moving boxes
Paul


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## Weldsol (Nov 18, 2021)

Got a bit more done over the last two weeks
All the oil / water /exhaust pipes which were in copper are now wearing a nice coat of Nickel via the vinegar / Nickel/ phone charger, for the Nickel I used the pure Nickel core wires from some cast iron welding rods.
Got the HT leads done apart from plug connectors (waiting on them along with the rest of the electrics including the plugs)
Got sort out making a Radiator / Fuel tank / way of starting, also got to dry run it for a bit just to bed everything in

Paul


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## Steamchick (Nov 19, 2021)

Hi Paul, is the electroplating for "a nice coat of Nickel via the vinegar / Nickel/ phone charger" as simple as that? When I tried copper plating, I managed to get a layer of copper that didn't stick to the steel I was trying to plate. - so I painted it instead... Do you simply pickle you parts before plating?
K2


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## Weldsol (Nov 19, 2021)

Steamchick said:


> Hi Paul, is the electroplating for "a nice coat of Nickel via the vinegar / Nickel/ phone charger" as simple as that? When I tried copper plating, I managed to get a layer of copper that didn't stick to the steel I was trying to plate. - so I painted it instead... Do you simply pickle you parts before plating?
> K2


First I'm not a plating Guru I just looked online to find the easiest /low cost way.
All the Nickel plating was on Copper / Brass / Bronze parts these were all pickled in Citric acid ( to remove all flux residues after silver soldering) then prior to plating given a thorough de-greasing.
The vinegar was 20% acidic (used in UK for weed killer ) plus a small amount of salt (one teaspoon to 2.5 ltr vinegar).
 the depth of coating was down to how much time / power of phone charger plus you can always keep  re dipping the part for a thicker coating.

Paul


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## Steamchick (Nov 19, 2021)

Thanks Paul. Sounds like my de-greasing wasn't any good. I thought after pickling it was de-greased.... only handled with tongs, but the copper simply wiped-off my stuff with my fingers.
Thanks for the help!
K2


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## Weldsol (Dec 24, 2021)

Found some more workshop time so got on with the radiator, I looked at the computer radiators but I did not want the inlet / outlets on the same side so sketched out an aluminium rad then worked out how to make it.
the pictures below will give you some idea how it was done.
I TIG welded the top & bottom closing plates though if you don't have welding kit then it could be made using bolted plates. 
The side plates I ended up slitting to get a better clamping effect for the fins to the tubes

Paul


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## Steamchick (Dec 24, 2021)

I used to use zinc based  rods for soldering aluminium, but now I used a fairly new solder that is 95% aluminium. (It is cheap!). Works very well, easy use use with a blow-torch. I have used to make small boxes for ceramic burners using 1mm aluminium sheet. Careful use of the flame avoids melting the whole lot, but I do not have TIG, and this makes very strong assemblies. As a method, it is not like capillary silver soldering or brazing, but much more like stick welding to make fillets of the added material. I have fitted 6mm aluminium tubes into the 1mm ally sheet , so this could make a radiator, if the material is big enough. But if I was making one with 4mm tubes, or smaller, I think I should make a brass assembly using silver soldered tubes into headers. Although they used to be made with lead soldered copper or brass in full size.
So lots of ways available without TIG.
K2


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## ozzie46 (Dec 24, 2021)

That radiator looks great. I am building a Sealion also and have been thinking about a radiator. would you consider sharing the particulars of your design?

Ron


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## Weldsol (Dec 24, 2021)

Steamchick said:


> I used to use zinc based  rods for soldering aluminium, but now I used a fairly new solder that is 95% aluminium. (It is cheap!). Works very well, easy use use with a blow-torch. I have used to make small boxes for ceramic burners using 1mm aluminium sheet. Careful use of the flame avoids melting the whole lot, but I do not have TIG, and this makes very strong assemblies. As a method, it is not like capillary silver soldering or brazing, but much more like stick welding to make fillets of the added material. I have fitted 6mm aluminium tubes into the 1mm ally sheet , so this could make a radiator, if the material is big enough. But if I was making one with 4mm tubes, or smaller, I think I should make a brass assembly using silver soldered tubes into headers. Although they used to be made with lead soldered copper or brass in full size.
> So lots of ways available without TIG.
> K2


I wanted an aluminium radiator and yes I could have ally gas brazed the whole thing (12% silicon ally brazing rod and flux) but the problem with brazing aluminium especially fillets is you cannot easily remove the flux (corrosive)
The design was done so that no welding or aluminium brazing needed to be used.
I welded the top and bottom plates because one I've got the welding gear and two it would have meant a lot of drilling and tapping but if you have not got the welding gear then the rad could still be made.
all the tubes are sealed by "O" rings (as shown in the pic's ) the tubes are machined from solid bar so I could have the flanged bits for the "O" ring closing the tubes are 6mm dia, with 1mm wall

Paul


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## Weldsol (Dec 24, 2021)

ozzie46 said:


> That radiator looks great. I am building a Sealion also and have been thinking about a radiator. would you consider sharing the particulars of your design?
> 
> Ron


Hi Ron yes I can put up some PDF's with no dimensions that will give you some answers
Paul


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## Weldsol (Dec 24, 2021)

ozzie46 said:


> That radiator looks great. I am building a Sealion also and have been thinking about a radiator. would you consider sharing the particulars of your design?
> 
> Ron


Hi Ron here is a general layout for the rad no dimensions as you can build it to what ever size / material size you want what is not shown is the side plates ( you can see them on the pic's I posted ) as these will depend on what size and amount of fin plates.
If you have any queries send me a PM 
Paul


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## Steamchick (Dec 24, 2021)

Hi Paul, you have done a splendid job making this radiator. I was adding my pennorth about the ally rods I use (flux free) as some with blow-torches but not TIG may be interested in the jointing material and method.
Another engineer in the club made a 1 1/2" x 2" radiator by machining 5/16" square brass bar with his narrow parting tool to make thin fins, drilled for fluid flow, and 5 of these tubes made the radiator assembled to top and bottom tanks. 
Except the radiator is too small for the waste heat from his engine. Looks nice to scale though, but limits running to 10 mins from cold.
I am sure there must be calculations to determine radiator size? (something another Engineer did at work, not in my box of tools!). Flucid   flow, fluid CSA, Air flow, Air Fin surface area and gap CSA... etc.  Some calculations will be the same as I did 40 odd years ago, on air-cooled electrical things,  but lost from memory now...
Must look things up on't interweb....
K2.


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## ozzie46 (Dec 24, 2021)

Thanks Paul, I'm looking at maybe a radiator about 4"1/2 x 5"x 1/2 thick.

Ron


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## Weldsol (Mar 30, 2022)

Finally got quite a bit done after a rubbish Christmas / January / February (my wife's mother died just a couple of days before Christmas so workshop time was a bit awkward)
So here is what I have managed to get done to date

Base board cut and pocket cut out for starter motor,
Starter switch gear put in a box,
Ignition system finished and boxed,(made to be detachable so it can be used for other engines)
Flywheel machined (had to removed 1/8"from the rear face) for sprag clutch bearing and belt pulley,
Starter motor mounting housing,
All now mounted including the radiator I have also fitted a regurgitation bottle to the the rad no fan is fitted at present as I'm not sure whether to go for mechanical or electric (I have left the crank nose long for a pulley if it ends up being mechanical)
My first try at getting it going was yesterday afternoon got a few pops & bangs and it would almost run, I noticed while looking down the carb, a couple of spit backs the firing order as per ETW was 1342 but then I remembered Basil had a similar thing so I swapped around so it's now 1243 and I lost the spit backs but it still would not get going.

So pulled the plugs and they were oiled up so gave them a clean out with lighter fluid put hem back then tried again.

This time I got a few steady pops (note I was playing with the mixture needle at the same time) then all hell broke loose on all four cylinders for about 3 or 4 sec's then it stopped cranked it again and got the same I think it is not pulling enough fuel (will try a bigger bore fuel pipe)

So not had it running long enough to do a vid, when I do I will put it on the site

One issue I will also look at is drilling the face of the flywheel close to the edge and insert several slugs of tungsten to replace the material I had to take off for the starter clutch

Paul


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## Steamchick (Mar 30, 2022)

Ee lad! That's a proper job!
Well done!
K2


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## Steamchick (Mar 30, 2022)

You need to check the compression on each cylinder - to get the correct firing sequence. - Just in case you have mis-timed something? We can all make mistakes, though it sounds like you have a near runner, so something is right.
K2


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## Weldsol (Mar 30, 2022)

Steamchick said:


> You need to check the compression on each cylinder - to get the correct firing sequence. - Just in case you have mis-timed something? We can all make mistakes, though it sounds like you have a near runner, so something is right.
> K2


Yes you are correct re compression for firing sequence , my brain was telling me 1342 firing order as most of my apprenticeship was on Standard Triumph's and they were 1342 so that's my excuse I'm sure Fords were 1243 
The cam timing was done by splitting the overlap on No4 to give me No1 firing and the distributor set with points just opening at TDC (I will be able to advance it a bit when I can get it for more than a few seconds.)
If you read ETW's notes he quotes  "It is really immaterial whether the firing sequence of the cylinders is 1243 or 1342 as the difference only calls for the appropriate connections to the spark plugs" this is quoted in the cam production notes.

Paul


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## Steamchick (Mar 30, 2022)

Hi Paul. I am probably being thick here.... but if the cam is set for 1342 for clockwise crank, you would have to reverse the rotation of the engine to have 1243 firing order.... and I understood that also to reverse the intake and exhausts.... I'm struggling to get my head around this! Just call me thick if I am wrong.
K2


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## Steamchick (Mar 30, 2022)

As I worked in engine design for a few years in the Automotive sector, I did a lot on peripherals, but the direction of rotation and firing order didn't come onto my desk. But the cam chain design did, and was very specific to the engine's rotational direction. (Tight side versus slack side). So (not knowing the Sealion) I would expect the direction of rotation - ergo firing order - to be quite critical?
K2


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## Weldsol (Mar 30, 2022)

Steamchick said:


> As I worked in engine design for a few years in the Automotive sector, I did a lot on peripherals, but the direction of rotation and firing order didn't come onto my desk. But the cam chain design did, and was very specific to the engine's rotational direction. (Tight side versus slack side). So (not knowing the Sealion) I would expect the direction of rotation - ergo firing order - to be quite critical?
> K2


In one respect you are correct as in chain drive as you say tight side vs slack side because of chain tensioner ( one exception would probably been the old mini A series as that had the two rubber bands on the cam gear which worked on centrifugal force.
In respect to the Sealion it is gear driven (4 gears including the crank one) and could actually be made to run either direction 
But the fact He stated both firing orders in the cam jig section and earlier on in his words that the crank direction should be CCW when looking from the front of the engine. it would have made more sense in the camshaft jig section to specify that his settings produced a 1243 firing order for his preferred crank direction.
But Hey Ho firing order now sorted and to add to that my points /coil ignition system works ok with no stray HF and that by using the Minimag MIC1A control I didn't have to use tungsten points as it only has 10 milliamps across the points.

Paul


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## Basil (Mar 31, 2022)

Very nice work Paul. Glad you got the firing order sorted. Rocking couples as I call them is always the easiest way for me to see the firing order. That is exhaust closing, intake opening for the particular cylinder and follow those every half crankshaft turn for a four cylinder. Of course these rocking couples are one crankshaft turn out from firing when setting your points. Apologies if I'm teaching to suck eggs. Excellent Job!


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## Weldsol (Mar 31, 2022)

Basil said:


> Very nice work Paul. Glad you got the firing order sorted. Rocking couples as I call them is always the easiest way for me to see the firing order. That is exhaust closing, intake opening for the particular cylinder and follow those every half crankshaft turn for a four cylinder. Of course these rocking couples are one crankshaft turn out from firing when setting your points. Apologies if I'm teaching to suck eggs. Excellent Job!



Hi Basil no need to apologise, and thank you for your info on the starter pulley's they worked out fine.
Paul


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## Steamchick (Mar 31, 2022)

Well done Paul, a nice engine! - Just a "point" on the "points"... the contact deterioration (arc erosion) is caused by the reacting current from the coil causing feedback when the contacts break. This (as I guess you know, but some other readers may not?) is countered by the capacitor, so the current rushing back out of the coil rushes into the capacitor (Old car buffs call it a condenser). It's a natural current caused by the back EMF of the coil. 
What we are trying to do is open the contact, so the stored energy (your 10mA rms) in the coil leaps out of the HV side across the spark plugs. But being energy that will escape every possible way, it also tries to rush back across the points from the LV side of the coil. This is the damaging current that literally "burns" the contacts... (Arc voltages cause iron molecules at over 2000 degrees C to burn in air). Steel contacts only last ~1000th of the life-time of platinum contacts (as on the Contact Breakers bought in the car spares shop). But if you polish off the arcing oxides from your steel contacts after each run I'm sure you'll manage. (I had a magneto on a Bike back in the 1970s with contacts that had had the platinum filed off by the previous owner. - I ran it on my bike, but cleaned the points every 200miles, or tank of fuel, until I managed to buy some new (maintenance free) parts. 
But now you'll tell me the Minimag MIC1A control does the "heavy current switching" - and you are right. I was thinking of simple "old-fashioned" non-electronic systems. (These electronic things were only invented in the 1970s, after my troubles with old, knackered bits!).
N.B. On "non-electronic" systems, If the capacitor fails, the points will burn incredibly quickly and you won't get many sparks at the spark plugs, as they will all be across the contact breaker points. (Been there, had that!). I have also had a distributor cap that had worn (arc eroded) so much that the sparks could not get across the gap to get to the spark plugs! A new cap and rotor arm (Measurably better!) sorted that unreliability. (My temporary fix was a thick bead of solder on the rotor arm contact. That got me to work nicely, without the previous mis-fires, until the new parts arrived). Ever wondered what the black dust is that collects in distributor caps? Or inside contact breaker chambers? (Sorry, stupid question, no-one does that!) - It is the vaporised metal from the contact arcs. - Being metallic oxides it also encourages flash-over inside distributor caps, from the high spark voltage there. So "Clean Caps" are best!
Hope my attempts at not "talking in electrical terms" helped some understand this? I can explain impedance, leading and trailing voltages and currents, but it confuses some non-electrical people.
K2


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## awake (Mar 31, 2022)

Paul, I am sorry to hear about your loss.


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