Stocker Pistons....Pontiac

Jeff Lee · 10-06-2012, 02:00 AM

Irregardless of any of the other pistons being lighter than the TRW's, the newer quality brand pistons have more accurately cut ring grooves. Not that many have not gone fast with TRW's over the decades (but then again, all that was available was TRW for decades if you wanted a good forged piston that was affordable). It's all about ring seal and it's worth power.
If you keep the TRW's, just check the vertical and radial clearances with the rings you use. There are shims available to correct problems. Rebco offers plenty of options if you want.

brent flynn · 10-06-2012, 08:19 AM

Thanks Jeff...I just want to make sure that using them isnt a waste of time and money... Im not lookin to set records, just yet. Building the best shortblock that i can right now, probably makes the most sense. Its easier to swap heads and cams out, as you go... even at that rate, was curious what the overall performance difference is that could be expected.

Alan Roehrich · 10-06-2012, 09:33 AM

When you combine the advantages in weight, ring grooves, and stability, the difference can be substantial. The TRW stuff weighs a ton, and really can't be lightened a great deal without causing problems. You can, and should, change the wrist pins, and have the pistons pin fitted, that will save weight, and increase reliability. I wouldn't spend any more than that, and balancing, on the TRW pistons.

GTX JOHN · 10-06-2012, 03:44 PM

My sons old 318 Engine was a TRW engine with lighter weight pins,

It would run about .8 - .9 under in decent conditions under current indexes.

The lighter better pistons with TriCity Rings were about .15 to 2 Tenths faster,

but half of the difference I would probably attribute to the rings and half to

the pistons.

Kegracing · 10-06-2012, 09:01 PM

Brent,
Great question. I have been wondering some of the same stuff, as I continue to scratch parts together for my 67 Firebird.

For the knowledgeable ones, another question please:

Would the heavier - less trick piston in a lower RPM Pontiac have less, equal or more impact to the overall motor efficiency, vs a generally higher RPM stocker motor, like a small block chevy?

Brent is talking about spending his money on a really good short block to start with. On a Pontiac 400 specifically, what is the best bang for the buck? Short block, heads, exhaust/headers ???

thanks, and good luck Brent

Ken

brent flynn · 10-06-2012, 09:22 PM

I'd say, good shortblock, obviously a good valve grind....good headers are a great investment, they can make alot of difference, especially with the high duration cams that we are allowed to run... Make sure you have a machinist thats knowledgeable in the ways of Stock Eliminator... that can make a huge difference on how much power you make, with the same parts...

Quote:

Originally Posted by Kegracing

Brent,
Great question. I have been wondering some of the same stuff, as I continue to scratch parts together for my 67 Firebird.

For the knowledgeable ones, another question please:

Would the heavier - less trick piston in a lower RPM Pontiac have less, equal or more impact to the overall motor efficiency, vs a generally higher RPM stocker motor, like a small block chevy?

Brent is talking about spending his money on a really good short block to start with. On a Pontiac 400 specifically, what is the best bang for the buck? Short block, heads, exhaust/headers ???

thanks, and good luck Brent

Ken

Paul Precht · 10-06-2012, 10:23 PM

Ring seal is where the difference is, weight is not worth much if anything. The lightest Hemi piston is heavier than the heaviest Pontiac piston.

10-06-2012, 02:00 AM	#1
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Stocker Pistons....Pontiac Irregardless of any of the other pistons being lighter than the TRW's, the newer quality brand pistons have more accurately cut ring grooves. Not that many have not gone fast with TRW's over the decades (but then again, all that was available was TRW for decades if you wanted a good forged piston that was affordable). It's all about ring seal and it's worth power. If you keep the TRW's, just check the vertical and radial clearances with the rings you use. There are shims available to correct problems. Rebco offers plenty of options if you want. __________________ Jeff Lee 7494 D/S '70 AMX

10-06-2012, 08:19 AM	#2
brent flynn Senior Member Join Date: Apr 2011 Location: Middletown, IN Posts: 593 Likes: 0 Liked 0 Times in 0 Posts	Re: Stocker Pistons....Pontiac Thanks Jeff...I just want to make sure that using them isnt a waste of time and money... Im not lookin to set records, just yet. Building the best shortblock that i can right now, probably makes the most sense. Its easier to swap heads and cams out, as you go... even at that rate, was curious what the overall performance difference is that could be expected. __________________ 1968 Bird/TRW 455/Home ported 13's, '70 Qjet,Holley Street Dominator manifold, Comp Solid FT, 10.817/122.30/1.440 Workin' on E/SA combo 3119 E/SA

10-06-2012, 09:33 AM	#3
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,126 Likes: 1,583 Liked 1,893 Times in 423 Posts	Re: Stocker Pistons....Pontiac When you combine the advantages in weight, ring grooves, and stability, the difference can be substantial. The TRW stuff weighs a ton, and really can't be lightened a great deal without causing problems. You can, and should, change the wrist pins, and have the pistons pin fitted, that will save weight, and increase reliability. I wouldn't spend any more than that, and balancing, on the TRW pistons. __________________ Alan Roehrich 212A G/S

10-06-2012, 03:44 PM	#4
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,737 Likes: 2,813 Liked 2,489 Times in 699 Posts	Re: Stocker Pistons....Pontiac My sons old 318 Engine was a TRW engine with lighter weight pins, It would run about .8 - .9 under in decent conditions under current indexes. The lighter better pistons with TriCity Rings were about .15 to 2 Tenths faster, but half of the difference I would probably attribute to the rings and half to the pistons. Last edited by GTX JOHN; 10-07-2012 at 03:38 AM.

10-06-2012, 09:01 PM	#5
Kegracing Member Join Date: Jun 2002 Location: Red Oak, TX Posts: 441 Likes: 0 Liked 0 Times in 0 Posts	Re: Stocker Pistons....Pontiac Brent, Great question. I have been wondering some of the same stuff, as I continue to scratch parts together for my 67 Firebird. For the knowledgeable ones, another question please: Would the heavier - less trick piston in a lower RPM Pontiac have less, equal or more impact to the overall motor efficiency, vs a generally higher RPM stocker motor, like a small block chevy? Brent is talking about spending his money on a really good short block to start with. On a Pontiac 400 specifically, what is the best bang for the buck? Short block, heads, exhaust/headers ??? thanks, and good luck Brent Ken

10-06-2012, 10:23 PM	#7
Paul Precht Senior Member Join Date: Dec 2001 Location: Elysburg, Pa Posts: 733 Likes: 361 Liked 327 Times in 121 Posts	Re: Stocker Pistons....Pontiac Ring seal is where the difference is, weight is not worth much if anything. The lightest Hemi piston is heavier than the heaviest Pontiac piston.