1934 twin engine rebuild

[BarryCambs]

The long two completed the YesterYear Road Run in the sun today An annual event in aid of our local hospice with over 300 motorcycles, cars and tractors - it is the Cambridgeshire fens after all. The only real issue being water leaks on the mainfold joints. The replacement manifold looks much better than the one I patched with filler, so I'm not sure what the problem is. I had a different type of gasket which look like exhaust gasket material (metal faced) but I'll try again with the plain type. I didn't use any sealant as the manifold looked so good, but that could have been a mistake, so I'll smear everything with silicon too. On the offside, water got into the cylinder so I'm a bit paranoid about it.

The increase in performance is a revelation. A slope which used to need full throttle in 3rd gear can now be done in top at 1/4 throttle while still accelerating. I'm being pretty gentle as it's only done 40 miles, but it's way better than I was expecting and I feel a lot more enthusiastic about it, now we can go further afield.

The new drag link has done wonders for the steering. It's gone from being "really scary" and quite dangerous to a "bit unnerving". Given there is no play in the steering box and I have replaced the ball joints with new from JCS, I was a bit puzzled, but it turns out the steering box is moving on it's mounting bracket. It looks like it is riveted on and the rivets have come loose.

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[k. rogers]

I have used the metal type gaskets in the past and I don't like them - they do leak! Make sure the manifold flanges are flat; file any raised bits out - then use 2 original type gaskets each side (a normal recommendation) with a smear of sealant on all faces and you shouldn't get any more problems.

[BarryCambs]

Thanks Keith. I have a couple of plain ones, but I'll order some more from JCS tonight. In many ways, I'm relieved to hear you don't like the other type, as the faces looked fine and certainly better than the manifold that came off. I was going to use silicone instant gasket as a sealant unless you have another suggestion?

Barry

[k. rogers]

You might get away with one gasket each side if you can barely get a feeler gauge between the mating surfaces, but I have always used 2 per side as suggested by many of the 'elders' years ago! That sealant should be fine.

[Tony Fearn]

Hi Barry and Ken.
What about a smear of engineer's blue on the mating surfaces with mild tightening of the nuts, and without gaskets for a start?
This would show whether you need to file the manifold.
I would also loosen off the cylinder base nuts again even though it's a bind, especially having to check the tappet gaps again.
I was told flat washers under these nuts, not spring washers.
As Ken says, 2 gaskets with sealant when you're happy the surfaces mate well.
I have never tried the sealant you mention, as I've used Blue Hylomar in the past, so I can't comment.
Make sure there's enough sealant on the thin bit of manifold between the inlet and water holes.
Please post a photo of the 'rivetted' steering box.
Tony.

[BarryCambs]

I like the idea of the Engineer's Blue and by chance, I have some leaking on the bench! I was wondering what the original gaskets were made from. I remember thermostat housing gaskets, rocker covers, timing chest etc being made from cork and that would certainly have more give than the modern hard gaskets. I'll have a good check over and double up the gaskets as advised.

I think the steering box might be off the 1934 car that donated its engine? I've not looked too closely as it was getting dark (this is an old picture) but I think the outer casing is riveted from the inside to the mounting bracket .

box.JPG

[BarryCambs]

Hi Tony. I have resized the picture you sent

1934 steering box.jpg

I think you're right, it is just the dust shield I can see moving. Thinking about it again, I wonder if it is the box twisting slightly on its bracket. Interestingly, the stabilising rod show as 2134x5 on the diagram has recently resurfaced in the bottom of the box where the oil thrower was. I thought it was a spare part of brake or clutch linkage. There is a home made rod bracing it to the chassis, but it's not very well made, or substantial and certainly not adjustable. I'll have another look and see if it can be either modified, or I can fabricate something better. I assume on the 1934 car the box is in a diferent position and this bolts straight to the chassis rail?

Barry

[BarryCambs]

The gaskets turned up and I found time to have another look at the manifold. The metal faced gaskets are thinner than the JCS ones and pretty rigid, so I think it would have been pretty lucky if they would have worked. Nipping the manifold down without gaskets and a bit of engineer's blue showed they were perfectly aligned front to back with no high spots. More than one person told me to tighten the manifold before the barrels and this is clearly good advice! However while everything was fine one the back side, on the chassis side there was a perfect 6 thou gap, all the way from the front to the back. Both sides of the engine have this perfect 6 thou gap, and it's on a odd plane and too perfectly symmetrical for it to be due to warping.

I suspect it could have been set up 6 though out when it was machined, then reversed in the mill and the error was reproduced perfectly the other side. There are machining marks on the faces, so it's not down to ham fisted filing and I don't see how the barrels can be to blame. Maybe it came out of the factory like that. Anyway, doubling the gaskets and smearing them with silicon instant gasket has cured the problem.

The steering box is twisting on it's mounts in ever direction, so that's going to need some more thinking about.

[Dhbangham]

Hi Barry and others, I have been running end float on my 1929 engine of about 1.5mm!!! for five years now. It was like that when I got the car. I am thinking about taking the flywheel off the crank to replace a thrust washer. Is now the time to sort out the float? I have not visualisation on how the crank is set up in the first place. Thanks in advance.

[BarryCambs]

Hi Daniel

I'm assuming the vintage engine is the same set up as the pre-war 1934 engine I rebuilt and that doesn't have seperate thrust washers as you'd expect in a more modern engine. Crank end float is controlled purely by the white metal main bearings. I did try 2 different thickness of gasket paper when I did mine to get it down to a couple of thou, but might be a bit hard pressed to lose 1.5mm!

I seem to remember Tony Fearn discovering a lot of play on his crank, but it didn't seem to have any ill effects and consensus was to pretend he hadn't noticed. Do you think it is causing problems? I thought the plan was to rebuild the original engine anyway?

As an aside, I do have a couple of 1/2" Whitworth studs and a heavy duty puller if you do ever want to take the flywheel off.

[Dhbangham]

Hi Barry, thanks for that. I am inclined pretend I did not notice, it has after all been driven 5000 or so as it is.
Since I don't need to remove the flywheel to get at the thrust bearings at the back of the clutch, I won't be taking the flywheel off. Thanks for the offer of the tools.
I have, however looked inside my gearbox and find some of my sprockets are getting excessively worn. Do you still have that spare gearbox? I would be interested in buying it if it is compatible with mine. Cheers
Daniel

[BarryCambs]

I'd arranged to leave the gearbox in Grantham so it could go to JCS, rather than me tripping over it for the next 30 years, but when I got back to Cambridge, I discovered it still in the back of the car! It's a 1932 centre change 3 speed box. It could well be some of the internals are the same as your earlier box. thought the service spec suggests different ratios.

jowett.org/jowettnet/dt/tech/jti/pw.pdf

You are more than welcome to it if Spanner Club wants to investigate it. I did take the top off and it looks in good condition.

[Dhbangham]

Yes please. You are obviously up and about this morning, I could come over now if that is OK with you. I changed phone recently and lost your number, you might still have mine, do you want to call.

[BarryCambs]

I have children - I'm always up and about We'll be going out about 9am for a couple of hours, but I'm happy to leave it behind the bins. I'll email you.

[Dhbangham]

Sunday afternoon update.
a) I have now removed and dealt with the original asbestos and brass rope around the cone. It seems to be 1/4 inch diameter and I have ordered some 6.5 mm Kevlar braided rope.
b) It turns out that I had a complete cone assemble on my spare engine. Rob Abineri and I took that out this afternoon and found that this cone has been modified to use flat friction material riveted in place. It would have been great to just swap it over, but I noticed that the rivets holding the cone hub onto the cone are loose. I will therefore replace them. We also noticed that I have been driving for 1000's of miles without the deep ball ball bearing race that supports the cone on the end of the crank case. I have now put a bearing on the running engine.
c) I tested the two thrust bearing on the flywheel side of the clutch and will not change them until I have tested with the new clutch ropes.
d) Several knowledgeable people inspected my gear box sprockets and told me not to change anything at the moment as I had at least 60% of my gear teeth are still engaging.