Perhaps it would be worth it to mic each piston and sleeve to check for
variations, which may account for the irrational occurance of the problem
among cylinders. An .0005" larger diameter piston and a .0005" narrower bore
from honing
at the critical location could make the difference under extreme heat. Also
buildup on the inside of the water jacket. Also
the type of piston being used. (Long or short skirt. Forged or cast), etc,
etc.
steve P.
----- Original Message -----
From: "MadMarx" <tr4racing@googlemail.com>
To: <fot@autox.team.net>
Sent: Sunday, November 09, 2008 3:24 AM
Subject: Re: [Fot] 87mm liner needed
> WhaT clearance value we are talking about?
>
> -----Urspr|ngliche Nachricht-----
> Von: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] Im
> Auftrag von Henry Frye
> Gesendet: Samstag, 8. November 2008 12:50
> An: fot@autox.team.net
> Betreff: Re: [Fot] 87mm liner needed
>
> Many thanks to Joe Boruch, I am all set partswise.
>
> Interesting follow-up, I brought the offending liner and piston to my
> machine
> shop and they said I overheated that jug. The piston had a black spot 90
> degrees from the crankpin, halfway up the skirt that matched the grooves
in
> the liner. The opposite side of the piston showed a little scuffing, but
no
> metal transfer yet. That is the area of the piston that expands the most
> when
> hot. Apparently, I was running insufficient piston to cylinder wall
> clearance.
>
> Here's the kicker, this happened to the front cylinder, number 1, closest
to
> the water pump. The last place I would expect to overheat a jug.
>
> So we are going to open up the piston to wall clearance some more across
the
> board...
>
> -----Original Message-----
> From: Henry Frye
> Subject: [Fot] 87mm liner needed
>
> I tore down my race engine yesterday and found I have one
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