Hi Paul,
BMC A & C series engines can take quite a large overbore.
I'm running the 85mm Denis Welch Cosworth forged pistons - its fractionally
over a 60 thou overbore (.064 I think?) - just over 3 litres.
The 3000 block can accomodate a much larger overbore, however - up to 3.3
litres
The fashion about 10 years ago was to run Volvo pistons in a 3000. The Volvo
pistons were relatively cheap, great quality, light, and deck height was
'closer' than most others. There are many Healeys here in Australia who've
done it. This mod took capacity to nearly 3.3 litres. There were head gasket
related issues with some competition cars running 3.3. litres & high
compresssion - which was cured with a special gasket - and there were a few
porosity issues - resolved by locktite vacuum injection of the block - but
there are quite a few road cars here at 3.3 litres.
There were also lots of 3 litre 100/4s - running Holden pistons - my old
100/4 was nearly 3 litres.
The Healey Factory (Rob Rowlands) & Butler & Rudd (Eric Rudd) did quite a
few 3.3 litre healey 6 cly engines.
I used to have a Sprite that ran 68mm Hillman Imp pistons - you can make a
948cc sprite engine into 1220cc with a small journal 1100cc crankshaft and a
set of standard Hillman Imp pistons....
:)
Best
Chris
www.myaustinhealey.com
----- Original Message -----
From: "PG" <britishcars@shaw.ca>
To: <healeys@autox.team.net>
Sent: Thursday, November 09, 2006 4:05 PM
Subject: Cylinder Bore
>I reviewed the archives for this question but could not find a definitive
> answer.
>
>
>
> Does anybody know the maximum over-bore that a 2.9 litre Healey engine can
> take.
>
>
>
> A thread in the archives alluded to +60 thousandths but there was no
> definitive conclusion.
>
>
>
> Also, Does anybody know the related displacement change by the resulting
> increase in the bore?
>
>
>
> Thanks
>
>
>
> Paul
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