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Re: Low Compression Motor

To: Scott & Glenda Meyers <autox@earthlink.net>
Subject: Re: Low Compression Motor
From: Mike Maclean <macleans@earthlink.net>
Date: Mon, 07 Dec 1998 11:01:43 -0800
Cc: Greg Mahney <mahney@central.murdoch.edu.au>, spridgets@Autox.Team.Net
References: <3.0.3.32.19981207145703.0087b9b0@central.murdoch.edu.au> <366BE83C.C84B259C@earthlink.net>
Reply-to: Mike Maclean <macleans@earthlink.net>
Sender: owner-spridgets@Autox.Team.Net
Scott,
     You forgot to mention, if you shave the head an appreciable amount, 
(anything
over .20 thousands) you must check your valve geometry.  If it is only .20
thousands clean-up cut, your geometry is brought "back when you have the cam
re-machined to a normal profile.  Anything more for gaining compression has to 
be
removed somewhere else in the valve train; ie; shorter pushrods or shimming your
rocker pedastals.  Just my thoughts.
                        Mike MacLean-60 Sprite

Scott & Glenda Meyers wrote:

> Greg Mahney wrote:
>
> > My Sprite has a "low compression" motor   ie it is the wrong engine for the
> > car, but it was designed to be a "low compression" version of the A-series.
> >  This is evidenced by the engine number which is:
> >
> > 9D-U-L-105729  (the "L" is for LOW")
> >
> > My question is What makes it "low compression".  is it the type of head?,
> > shorter stroke?  different pistons?
> >
> > Anyone know the answer to this one?
>
> I believe the factory had two different sets of pistons, each with a different
> "dish" creating two different compression ratios.
>
> Aftermarket folks vary pin placement in the psiton as well as amount of dish
> for different compression ratios.
>
> Once can always shave the cylinder head for more compression if you don't want
> to change pistons, but, once shaved, it is forever!
>
> Scott Meyers
> 60 Bugeye 1275




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