Stocker Pistons....Pontiac

brent flynn · 10-05-2012, 11:26 PM

How much E.T. is a set of Venolia's or CP's, worth, over TRW's?
Just curious... I have a new set of TRWs(got a smokin deal on them)...
Just want to know if they are worth using on my 1st build... anybody still runnin them? Thanks in advance!
Im on a tight budget, so i will probably go with what i got...any info is helpful...

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.

Jeff Lee · 10-06-2012, 11:44 PM

Ring seal - Ring seal - Ring seal
That's the ABC's of a great short block. I didn't mention before that the skirt's are ground differently on todays good pistons which allows for better ring seal on piston rock-over. Plus the wrist pin bosses are better positioned for the same reason, better position and ring stability on rock-over. You won't find any of these benefits in an old TRW piston.
I understand being on a tight budget. But I also adhere to doing it right even if it takes longer. Obviously I adhere to that...

Rick Unterseh · 10-09-2012, 10:39 PM

Jeffy, Jeffy, Jeffy, I agree with you on the ring seal,,, 100%, but the assembly has to weigh a certain amount, no matter what piston, rod, ring set up. I've run fast with FACTORY .030 pistons.... oh wait... that is what I'm still running, and even in the new motor too !!!!!!!!!! You are telling me and the rest of the world that you can't run fast with heavy pistons nowadays?????... tell that to me one more time, and Harry, and Jon, and Fred, and many, many others. I'm putting together a motor for the car that I think/hope will run fast. I challenge you to bring out the AMC/Mopar with stock rocker arms, stock rearend... mine has both. ... Name the date, track and time... I'm there.

ready, willing and able. Lets see how far under you can go... no scoreboards,,,, just timeslips.

10-05-2012, 11:26 PM	#1
brent flynn Senior Member Join Date: Apr 2011 Location: Middletown, IN Posts: 593 Likes: 0 Liked 0 Times in 0 Posts	Stocker Pistons....Pontiac How much E.T. is a set of Venolia's or CP's, worth, over TRW's? Just curious... I have a new set of TRWs(got a smokin deal on them)... Just want to know if they are worth using on my 1st build... anybody still runnin them? Thanks in advance! Im on a tight budget, so i will probably go with what i got...any info is helpful... __________________ 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, 02:00 AM	#2
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 2 Times in 2 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	#3
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	#4
Alan Roehrich VIP Member Join Date: May 2006 Location: Murfreesboro TN Posts: 4,915 Likes: 996 Liked 1,043 Times in 274 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	#5
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,530 Likes: 2,222 Liked 1,809 Times in 572 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	#6
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	#8
Paul Precht Senior Member Join Date: Dec 2001 Location: Elysburg, Pa Posts: 690 Likes: 281 Liked 224 Times in 89 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.

10-06-2012, 11:44 PM	#9
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 2 Times in 2 Posts	Re: Stocker Pistons....Pontiac Ring seal - Ring seal - Ring seal That's the ABC's of a great short block. I didn't mention before that the skirt's are ground differently on todays good pistons which allows for better ring seal on piston rock-over. Plus the wrist pin bosses are better positioned for the same reason, better position and ring stability on rock-over. You won't find any of these benefits in an old TRW piston. I understand being on a tight budget. But I also adhere to doing it right even if it takes longer. Obviously I adhere to that... __________________ Jeff Lee 7494 D/S '70 AMX

10-09-2012, 10:39 PM	#10
Rick Unterseh Member Join Date: Jul 2006 Location: Phoenix, Arizona Posts: 133 Likes: 3 Liked 31 Times in 7 Posts	Re: Stocker Pistons....Pontiac Jeffy, Jeffy, Jeffy, I agree with you on the ring seal,,, 100%, but the assembly has to weigh a certain amount, no matter what piston, rod, ring set up. I've run fast with FACTORY .030 pistons.... oh wait... that is what I'm still running, and even in the new motor too !!!!!!!!!! You are telling me and the rest of the world that you can't run fast with heavy pistons nowadays?????... tell that to me one more time, and Harry, and Jon, and Fred, and many, many others. I'm putting together a motor for the car that I think/hope will run fast. I challenge you to bring out the AMC/Mopar with stock rocker arms, stock rearend... mine has both. ... Name the date, track and time... I'm there. ready, willing and able. Lets see how far under you can go... no scoreboards,,,, just timeslips.