That must be why Wiseco wants 0.006 clearance with their forged pistons.
Tim
-----Original Message-----
From: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] On
Behalf Of Jim Gray
Sent: Wednesday, November 14, 2012 8:52 AM
To: 'Duncan Charlton'
Cc: fot@autox.team.net
Subject: Re: [Fot] I have piston shrinkage
They are forged Wiseco's
jg
-----Original Message-----
From: Duncan Charlton [mailto:duncan.charlton54@gmail.com]
Sent: Wednesday, November 14, 2012 7:44 AM
To: Jim Gray
Cc: fot@autox.team.net
Subject: Re: [Fot] I have piston shrinkage
Jim,
That's pretty surprising -- what is the brand of piston? Cast or forged?
Duncan
(Texas)
1952 Morgan Plus 4
Red #6
On Nov 13, 2012, at 8:37 PM, Jim Gray wrote:
> FoT
>
> Tonight I was reminded of the reason you don't measure stuff in the cold.
In
> a hurry
>
> to use my new measuring tools I shot straight out to the garage and
started
> my post season
>
> measurements after the teardown. My pistons & liners look great so I was
> expecting everything to be
>
> well in spec with about 15 hours on them. I was horrified when I was
coming
> up with a
>
> consistent .008 -.009 clearance. I measured the surface temp of the
pistons
> at 59 -60 degrees.
>
> So I boiled some water and soaked the pistons for a few minutes. They came
> out at 92 degrees.
>
> The pistons grew .004" and puts them right in spec. That's a lot of growth
> at a 32 degree increase in temp.
>
> The liners measured out the first time within .001 of spec for the most
part
> at 60 degrees.
>
> jim g
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