Lotus Elan

Engine Build - Blog and Questions

PostPost by: stelz » Fri Jun 24, 2022 11:26 pm

Morning all - By way of introduction, my Elan project is back on, having started and moth balled it an embarrassing number of times over an embarrassing number of years. Car is 26/3853 so is a late S1 with some S2 body components.

Anyway, I am into the engine assembly and will put update posts up here as it progresses, and ask questions of the learned community as I go.

The engine is an L Block with long stroke crank and the short pistons. Machining / measurement is all complete and the assembly has begun - crank and pistons in :
IMG_0254(1).jpg and

Next steps will be the rear seal, front plate / timing cover etc... oil pick-up and sump to complete the bottom end and it can be flipped over.

Which brings me to a question, I have 7 timing sprockets which all seem like they are interchangeable for the jackshaft and camshafts, so I'm wondering if I should just choose the 3 best ones or if I am overlooking a detail and trap - photo below of the items I have:
IMG_0253(1).jpg and

Any guidance on which ones to use and on which shaft (jack, inlet can, exhaust cam) would be appreciated.
Thanks in advance, Ben
Last edited by stelz on Sat Jun 25, 2022 4:57 am, edited 1 time in total.
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PostPost by: rgh0 » Sat Jun 25, 2022 1:30 am

Hi Ben
Your photos are not coming up.

The sprockets are identical except for the timing marks on the inlet and exhaust sprockets, thre were no marks on the jackshaft sprocket. Normally only the Exhaust sprocket has "Ex" etched into its front. Replacement sprockets may have 2 timing marks labelled "In" and "Ex".

I would normally choose the best sprockets in terms of wear and time the cams from scratch using dial guages and remark the sprockets if needed.

cheers
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PostPost by: 2cams70 » Sat Jun 25, 2022 3:20 am

Unless your existing sprockets are almost new it’s not really worth keeping them. They are a wear item and you are better off replacing them all including the crankshaft sprocket if you are doing a major rebuild. The cost isn’t that great and as far as I can tell the new sprockets you get these days from the usual suspects seem to be of good quality.
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PostPost by: rgh0 » Sat Jun 25, 2022 3:43 am

Hi 2Cams
I generally find wear on the cam sprockets minimal and almost zero on the jackshaft. However the crank sprocket wears much more and I agree with routinely replacing these. Cams sprockets also easy to replace without a full engine strip down if needed. compared to the crank sprocket.

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PostPost by: 2cams70 » Sat Jun 25, 2022 4:52 am

Yes definitely the crank sprocket wears the most since it is the smallest and drives everything else. Always replace this. Jackshaft sprocket wears the least.
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PostPost by: stelz » Sat Jun 25, 2022 4:59 am

Thank you both - I will inspect all those sprockets carefully, especially the crank, and assess reuse vs. replace.
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PostPost by: stelz » Sat Jul 02, 2022 4:09 am

Some progress, rear main seal installed. I had a seal carrier from a 711M block which had what I guess are alignment guides to ensure the seal is concentric with the shaft - only 1.5 thou clearance, but I guess that is OK.
IMG_0255.jpg and

I'm awaiting delivery of some parts for the front cover, but have done a trial fit and found the back plate is not quite flat. Fitted here without the timing cover, just the single 1/4" bolt and the max gap to block is 40 thou
IMG_0256.jpg and

IMG_0257.jpg and

I am fairly sure this will pull in with the timing case, but wondering if there is an easy way to flatten out. Thoughts ?
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PostPost by: Craven » Sat Jul 02, 2022 10:56 am

Later lip seal carrier has a wider cork sump fitting, worth checking out before you go too far.
Fit of a NEW timing chain will indicate if your sprockets are badly worn.
Not that unusual for a back plate, will pull up if not far from a through bolt
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PostPost by: stelz » Sun Jul 03, 2022 7:39 am

Glad I posted re the rear main seal carrier, as it does have a wider groove for the cork seal. Off she comes next weekend! Thanks for pointing that out - love the community input to avoid head scratches or worse still mistakes.

I have managed to turn up the alignment tool for the front seal on the lathe today, so time permitting, should get front, back and even the sump on done next weekend.
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