Chevy piston in an A

[d.j. moordigian]

While doing some research on my B engine build, I found I have a number of questions.

With the crank offset .125" and a "stock Chevy piston" having a .060" offset
pin. Which way are you guy's installing the pistons,..arrow to the "front" or
to the "back"?

Now that Rich at " Antique Engine Rebuilding" has correct rods for the Chevy
pistons,...which corrects the "compression distance", that's a NO BRAINIER.
But were still back to the stock Chevy piston with the offset pin. Same question as above!?


Back in the 60's we used to change the piston direction too change the torque characteristics of the engine. Just an aside..

Since I have stock B rods and pistons ready to go,..I'll probable use that
combination. But if I didn't,..Rich's rods with custom pistons( with no valve
reliefs) and a proper ring set-up would be the way to go,..and you don't
need to deal with the offset pin bore problem..

So,..are we reinventing the wheel?...or making it better?....or making it cheaper?

[RawhideKid]

Talk to the guys at Eggy.com as I believe they can make the Chevy pistons with the proper offset to fit the A/B block and crank.

[George Miller]

I run them with the mark to the back. That gives you about the right amount of off set. But some pistons are different on the thrust side. So you will have to decide what is best for you.

[d.j. moordigian]

Originally Posted by RawhideKid

Talk to the guys at Eggy.com as I believe they can make the Chevy pistons with the proper offset to fit the A/B block and crank.

No way!
I had to redo an 8BA that someone else built with 180 miles on it,..it had
Eggy pistons. I replaced them,..the reason was that the rings had .002" to
.003" clearance. Rings will "flutter" and pump oil and have blow-by..

[RawhideKid]

Originally Posted by d.j. moordigian

No way!
I had to redo an 8BA that someone else built with 180 miles on it,..it had
Eggy pistons. I replaced them,..the reason was that the rings had .002" to
.003" clearance. Rings will "flutter" and pump oil and have blow-by..

So, because someone else placed the wrong rings on the Eggy pistons in a V8, you are blowing off the whole company and everything they make.

Makes perfect sense to me. *shakes head*

[wrndln]

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RawhideKid,
Once bitten, twice shy, as the saying goes! Why would you try them a second time, so you could probably have the same result again. Makes perfect sense.
Rusty Nelson

[Patrick L.]

Originally Posted by d.j. moordigian

No way!
I had to redo an 8BA that someone else built with 180 miles on it,..it had
Eggy pistons. I replaced them,..the reason was that the rings had .002" to
.003" clearance. Rings will "flutter" and pump oil and have blow-by..

Hmmm. I'm thinking you're talking about land clearance [ not end gap] and I'd like .002-.003". Anything under .005" has always made me happy [ for a normal engine]. So, what have I been missing ?

[d.j. moordigian]

Patrick,

To show my point,..I have a WELL used "custom" piston and Speed Pro ring to measure.
With "gauge pins" I measured .0635" in the ring groove, next the ring, .0625". That's
only .001" of clearance! When the piston is running and hot the vertical clearance of
the ring grove GROWS,...and the ring only grows in length, hence the "ring end gap".
Ya,..I know the ring PROBABLE grows in vertical height 1 or 2 tenths,..but all I care
about is when it's sitting on the bench, the fit.

That mite be a good experiment, heat the piston just below it's melting point and measure the ring land?...somewhere around 400-450 degrees? The top of a piston
will run @ 750 degrees too well over 1000 degrees.

Does this help?

btw,...just measured a stock Ford piston and ring with 150,000 + miles, and it
has .005" of clearance...