Piston ID?

[Nick ALFANO <71amx@xxxxxxxxxxxxx>]

Tom,

That looks like a TRW/Speed Pro part number for a
forged piston.  Not sure of the compression ratio as I
don't have a TRW or Speed Pro cross reference book
handy but if you look it up there, you should be able
to find out the exact specs.    

Nick Alfano


Date: Mon, 30 May 2005 23:03:20 -0700 (PDT)
From: Tom Jennings <tomj@xxxxxxx>
To: AMC List <mail@xxxxxxxxxxxx>
Subject: Piston ID?
Message-ID: <20050530224524.R1488@localhost>

My .030" over 258 has pistons marked "L3103F". Google
turns up
nothing. Can anyone ID it?

The head appears to be stock; stock size valves, no
evidence of
porting.

The flat of the pistons come up to approx. .036" of
the deck, and
the dish on the pistons are 3/16". A Felpro gasket I
have, the
thinnest point is .050". The piston dish covers most
of the
piston, so there's not a lot of squish space, but it
should be
.087". This doesn't sound like high-compression to me
(what the
engine is alleged to be). I know there's a dynamic
aspect to
compression but I don't know anything about it, and I
have no idea
what cam is in there. It's got double valve springs,
the inner are
flat wire.

I suppose I could get a degree wheel and measure the
cam.

Man, I'm itching to build a motor and do this crap
right.