Piston Questions
Turbo Mini Forums

Evening Guys.

Today i stripped down a pre a+ engine i was given, and i have a couple of questions about the pistons that were in there.

The numbers on the top are '21251 +030'

Does anyone know anything about these pistons?

Im guessing the '+030' is the piston 'over size', however i've never seen them this size before, only in +0.020 and +0.040 etc.

They seem to be in good condition, apart from a tiny nick on the edge of the crown, and other slight marks, as shown in the pictures.

Do you think they'll be re-usable if i can get rings, as i'd like to rebuild the engine pretty much as is, with just the usual bearings etc to be a road engine, for the daily driver.

Also, if they are any good, what do you think is the best way to get all the carbon off them?

Sorry about all the questions, when rebuilding engines i normally just replace pistons, but as this is just ment to be a low budget rebuild, i thought best to re-use them.

Any Help would be greatly appreciated.

Cheers, Oli.

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Edited by Oli on 29th May, 2009.

I don't know abot the piston part number but +015 and +030 were common oversizes years ago - they only became +020, +040 etc. to match metric sizes (+0.5mm, + 1.0mm).

I still have an early "A" block and pistons at +015....

But getting 030 (or any early imperial oversize) rings may be a problem...

Schrödinger's cat - so which one am I ???

Never heard of +0.015", do you mean +0.010"?

ahhh right, cheers Rod, well I'll have a browse and ring round to see if i can get rings.

But it sounds like an overbore may be on the cards.

21251 pistons are shite and should be nowhere near a high performance engine, turbo or not.

I've had a set in .030. You cannot get rings for these anymore, but you can modify .040 ones.

Cheers for the information Vegard, i'll have an over bore then, and get some new pistons.

Cheers for the help.