I used to turn mine out of Lucite. You make it a snug sliding fit then
turn a relief near the top, drill down through the center, then saw off
the top inch and turn a step into it a little deeper than the ring depth
and a little shallower than the thickness. Tap the hole so you can clamp
the ring with the piece you cut off using a screw in the center hole.
Sounds harder than it is, I made dozens of 'em.
You lap the ring until you get a even haze all the way around. How long
that takes is an open question. Generally too long. One other
complication, you need to bore and hone the cylinder with a full clamping
tension. For most motorcycle engines that meant a torque plate top and
bottom because they have through bolted cylinders. On a Triumph I guess
you could just make a plate to put the wet sleeve under full torque
clamping pressure.
If you don't do all that it's not worth the effort to hand lap--the
cylinder distorts out of round and you're lapping to a shape it will never
assume under torque.
I don't really know that this is worthwhile for car racing. We were
running engines that we tore down to itty bits after every race and always
replaced the rings, and most of everything else--there was no time to
break an engine in--by the time it was broke in it was broken.
I was nuts then.
Or at least more nuts.
-----Original Message-----
From: Gt6steve@aol.com [mailto:Gt6steve@aol.com]
Sent: Tuesday, April 02, 2002 7:28 PM
To: Bill Babcock
Subject: Re: Engine run-in
Hey Bill,
Will you elaborate on the details for the jig to lap the rings? I picture
a
dummy piston without any clearance to keep it all square. How long does
it
take per hole? I'm sure all of us would be interested. Thanx, Steve
Smith
>
> The real, real best way is to make a jig to hold the ring and lap them
in
> by hand to the bore they're going to run in. Used to do this to racing
> motorcycle engines. When you're not married you can do it in front of
the
> TV in the living room. Not nearly as much fun in the freezing shop.
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