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Re: [Healeys] CR

To: Austin Healey <pajtamuvek@gmail.com>, Healey List <healeys@autox.team.net>
Subject: Re: [Healeys] CR
From: Alan Seigrist <healey.nut@gmail.com>
Date: Tue, 22 Mar 2011 23:33:24 +0800
Oh, don't skim anything.  Get the proper pistons.  Once you skim you
can't ever fix your head/block after that - it's a one way trip.

You don't want compression more than 9ish to 1, no one makes gas that
has high octane anymore.  It's no fun to have to add octane boost to
every tankful.  It's best if compression is around 8.5:1 for ease of
using modern fuels.

Alan

On 3/22/11, Austin Healey <pajtamuvek@gmail.com> wrote:
> Hi,
>
> I have just collected my engine from my machinist (rebore, crankshaft
> reground, new cam bearings etc). For my greatest solace, he folloved all my
> instructions, soo all the clearances are accurate (=>
> hipp-hipp-hurrey!!!!!).
>
> Now I have made some measurements with the new pistons.
>
> I had to experience that the new reproduction pistons are quite a bit lower
> than the originals! If You can remember, my engine is a "26H", soo may be
> some kind of "special" engine. The original pistons came about 0.3mms *above
> *the dech height. The new pistons are 1.75mms below the deck.
> I am using a 12 port head (non-original to this engine, original lost). I
> have counted a rough 7.6:1 CR now with my new pistons. This is *very* low.
> Whats Your opinion: shall I get the block skimmed by 2mms, and get the
> pistons to the "original" height, skim the head, or skim both to get a
> higher CR? What numbers to go for? 9.5:1? Or higher?
>
> Gergo
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