Lotus Elan

Cast Pistons

PostPost by: Ianashdown » Sun Nov 24, 2024 7:52 am

I am going through a recently acquired Twin Cam kit of parts. It has 0.030” oversized cast pistons which are in good condition, and I think the bores can be recovered with a light hone.

This engine will be built with very mild tune to power my ‘61 Lotus 7, which will, I hope, give plenty of power for such a lightweight car.

My question is: are these cast pistons worth using at all or are forged pistons an automatic replacement.

Thanks

Ian
Last edited by Ianashdown on Sun Nov 24, 2024 3:59 pm, edited 2 times in total.
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PostPost by: 512BB » Sun Nov 24, 2024 8:01 am

Absolutely nothing wrong with cast pistons, I use NOS cast pistons all the time in my rebuilds. Obviously you will need to use a new set of rings. What I have found though, is that the weights of individual pistons can vary a lot between the set and careful shaving needs to be carried out. Also make sure that the slots that the rings fit into is within spec, and not sloppy.

Leslie
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PostPost by: elans3 » Sun Nov 24, 2024 2:47 pm

+1 for cast pistons, no need at all to go forged unless you're building a proper competition engine.
Current :- Elan S3 DHC SE S/S 1968,
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Elan S3 DHC SE SS 1968,
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PostPost by: StressCraxx » Sun Nov 24, 2024 4:29 pm

I replaced my original std bore pistons in 1982 with 0.020" oversize cast pistons. Another 100K miles, we rebuilt with new rings on the 20 over pistoins. Still good.
There is no cure for Lotus, only treatment.
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PostPost by: Ianashdown » Sun Nov 24, 2024 5:52 pm

This is good news! If I can get a good finish in the bores with a light hone I should be able to re-use pistons and rods. The crank needs to be replaced I think, it has some rust that may be a bit too deep and is a 4-bolt. I’d like a 6 bolt and I’d like to keep the standard stroke. What is a good crank to use?

Thanks,

Ian
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