end feed converion

[johnjag]

Hi all - back again. Sorted the starting and running of my Mk11 Spitfire but I am now left with the rattle I mentioned. Bob Price (A65 Guru) says it is the idler timing gear bushes. So I need to remove the inner timing case to fix. Thing is, it is fitted with the end feed conversion and as I have never stripped one of these before can you tell me what to expect on removing the cover and how carefull I should be not to damage anything. Are there usually oil seals that need replacing. I do not know who did the conversion but from the outside it looks very neat.
Thanks
John.

[Bess]

Hi,
    Mine is a SRM conversion.

The outer cover has an oil seal, so withdraw the cover as horizontally as possible to avoid damage, the inner cover has an O ring, nothing  special to worry about. Ensure they are in good order before reassembly.

When assembling I use the SRM gaskets as they have larger holes around the oil feed to the quill, ensure the gasket holes do not impede the oil flow.

Best wishes...

[johnjag]

Thank you Bess - what an asset this Forum is!
Regards
John.

[ChrisG]

You mention the outer cover has an oil seal. I've not seen the SRM conversion lately but my Thunderbolt has the Devimead conversion, which was done before Steve McFarlane bought the business and subsequently John & Co at SRM bought it from Steve.
On mine it's the inner cover that has the oils seal that fits over the quill on the crankshaft and at about 5 o'clock on the crankcase outer face next to the bolt hole is the oil feed hole with an O ring groove. This connects with a corresponding hole on the inner side of the inner cover and into the welded on lump which transfers the oil to the centre to connect up with the crankshaft feed.
The only difference between the Devimead and SRM as far as I know is the oil seal for the crank quill is smaller OD. This was to reduce the force behind it due to the surface area of the Devimead one which used to 'pop out' under the increased pressure.
The main concern I had was the aforementioned  O ring groove/recess, this comes very close to the edge of the gasket face so I used  some silicon gasket around the O ring to a) hold it in place and b) hopefully stem any oil squeezing around the outside of the O ring.
Chris

[Bess]

Hi,
    I should have said mine is a A10, SRM conversion. However the oil seals and precautions are similar.

Sorry...

[Mel]

There was another variant of end feed conversion the Bill Cooper, National sidecar racer, used to make and run.
I bought an A70 crankshaft  from him when increasing the A65 to 840cc and used his conversion.
Although its over 40 years since I used this, from memory there was a 'top hat' with a triangular base that bolted to the inner timing cover. The top hat contained the oils that fitted over the quill. Thus, it could be positioned by letting the seal self centre on the quill and then the triangular plate was nipped up. Oil was fed by pipe from the oil pressure light take off through a hole in the outer cover to the top hat.
My current engine that has the Devimead 750 Barrels also has the Devimead end feed conversion. The 500 motor with the ex Chris Vincent top end,  just has the bush in the bottom end, at least until after it has been run and tested to see what I end up doing with it.

Mel