Ol' Fart's Firebird Fantasy

[oldskool]

Originally Posted by Adam Strang

Go to the NHRA site and look under approved products.The number is P5-CP.Got them approved a year and half ago.

OK, got it--page 60. What did you have to do to get CP to make this piston ?

http://www.nhra.com/userfiles/file/N...edProducts.pdf

[oldskool]

Subject: Stocker cams

Question: I think I have ask this on the site before, but do not remember getting an answer. So, what brand of cam do most of the top Stockers use ?

Bullet is the brand I see mentioned most. They have quite a few lobes listed, and can do custom grinds also.

http://www.bulletcams.com/Masters/Hlobes.htm

I assume that most cam grinders don't fool with Stocker stuff because there are so few Stockers around.

[HandOverFist]

Comp Cams will grind whatever you want.

[Dave Ribeiro]

oldskool,

I have used CC in both my 350 & 400 ci 77-Pontiac firebird ..They have a wide selection of grinds to choose from & very good service...I use Crower dual- valve springs & CC hyd lifters , also use Rhoads lifters at times ... Yes, I run 160 # plus spring pressure & CC mag. pushrods, in a 3850 # bird.You don't need all the good stuff to run 2-3 under the index , you will need a good trans & Convertor , plenty of TNT... A good sealing short-block ,heads & a good Q-jet ? Good Luck, $$$$ - jump in the waters is " Fine "...

[oldskool]

Originally Posted by Dave Ribeiro

oldskool,

I have used CC in both my 350 & 400 ci 77-Pontiac firebird ..They have a wide selection of grinds to choose from & very good service...I use Crower dual- valve springs & CC hyd lifters , also use Rhoads lifters at times ... Yes, I run 160 # plus spring pressure & CC mag. pushrods, in a 3850 # bird.You don't need all the good stuff to run 2-3 under the index , you will need a good trans & Convertor , plenty of TNT... A good sealing short-block ,heads & a good Q-jet ? Good Luck, $$$$ - jump in the waters is " Fine "...

Now that's what I wanted to hear ! Reasonable spring pressure, and Rhoads lifters. That means I can run a reasonable cam with Rhoads lifters, in my 455, and get by with a little less spring pressure than you need with your 350 & 400, because I'll be turning less rpm with the long stroke motor--6000 rpm or maybe even a bit lower. Does this sound reasonable ?

Also, with the 455 and Rhoads lifters, I can get by with less stall, and use the 500 + ft lbs of low end torque. Correct ?

[oldskool]

As I mentioned at the beginning of this thread, it's main purpose is to gather good Stocker info, not only for myself, but also to help others like me, who have less experience with Stocker stuff.

The only way I know to get this info is to ask those who have Stocker experience, and to find good online info. So I'll just keep firing the questions as I think of 'em.

Subject: Pistons

Question: (1) I see that for some engines there are several NHRA approved forged pistons. So, even if the stock pistons had press pins, are these approved pistons allowed to have floating pins ?

(2) Are all these pistons required to have the same number, size and depth valve reliefs ?

(3) I see that NHRA sets the min weight for the piston. But the min weight for most Pontiac pins is listed as 90 g. That seems like an awfully light pin, doesn't it ?

(4) Also, several of the rods approved for Pontiacs have .990 BBC pin holes. So does that mean that you can order these approved pistons with either size pins ?

http://www.classracerinfo.com/Engine...px?ENGINE=2048

[Mark Yacavone]

Originally Posted by oldskool

As I mentioned at the beginning of this thread, it's main purpose is to gather good Stocker info, not only for myself, but also to help others like me, who have less experience with Stocker stuff.

The only way I know to get this info is to ask those who have Stocker experience, and to find good online info. So I'll just keep firing the questions as I think of 'em.

Subject: Pistons

Question: (1) I see that for some engines there are several NHRA approved forged pistons. So, even if the stock pistons had press pins, are these approved pistons allowed to have floating pins ?

(2) Are all these pistons required to have the same number, size and depth valve reliefs ?

(3) I see that NHRA sets the min weight for the piston. But the min weight for most Pontiac pins is listed as 90 g. That seems like an awfully light pin, doesn't it ?

(4) Also, several of the rods approved for Pontiacs have .990 BBC pin holes. So does that mean that you can order these approved pistons with either size pins ?

http://www.classracerinfo.com/Engine...px?ENGINE=2048

1 Yes, you can float the pins

2 Yes NHRA approved number

3 Don't argue about it, and don't use a lighter pin than you have to.

4. You can use a .980 pin or LARGER if rod is approved.

[oldskool]

Originally Posted by Mark Yacavone

1 Yes, you can float the pins

2 Yes NHRA approved number

3 Don't argue about it, and don't use a lighter pin than you have to.

4. You can use a .980 pin or LARGER if rod is approved.

OK, so the optimum set-up would be to use a rod / piston / pin / ring combo which would just barely meet the NHRA min weight--is that correct ?

So, for this 350hp 400, that total weight would be 1458 g.

http://www.classracerinfo.com/Engine...px?ENGINE=2048

But I noticed some more specs on this page I need to ask about.

(1) The comp dist is listed as 1.695. But one of the approved pistons has a comp dist of 1.714. So, does that mean that you can use any comp distance you choose, which will optimize your combo with one of the approved length rods, and the max allowed stroke ?

http://www.summitracing.com/parts/sl...w/make/pontiac

(2) Wouldn't there be an advantage to running one of the BBC rods, because of the smaller big end and larger selection of cheaper pins ? The rod journals and bearings will be smaller, and lighter, with less bearing surface. All this will make the rotating assembly lighter, and should rev a bit quicker. Nothing major. But every little bit helps.

(3) That was for the optimum set-up. But it is also the most expensive. So, that brings up my final piston / rod question. Since the SP(TRW) pistons are MUCH cheaper than the other approved forged pistons, is it possible for a low buck guy to use the cheaper pistons and 6.625 Pontiac rods, and build a shortblock that can run slightly under ? Or to ask it another way, aprox how much quicker would the high dollar shortblock run than the low budget one I described ?

[Dwight Southerland]

1) Compression distance is minimum, not required.
2) Yes.
3) a) Yes. b) Reciprocating assembly optimization might be worth .12, including reduction of bearing size and weight.

[Billy Nees]

Originally Posted by oldskool

(3) That was for the optimum set-up. But it is also the most expensive. So, that brings up my final piston / rod question. Since the SP(TRW) pistons are MUCH cheaper than the other approved forged pistons, is it possible for a low buck guy to use the cheaper pistons and 6.625 Pontiac rods, and build a shortblock that can run slightly under ?

Yes


Or to ask it another way, aprox how much quicker would the high dollar shortblock run than the low budget one I described ?

With a "tow truck" motor? Maybe not as much quicker as you think.

Now can I make a suggestion? Seeing as you apparently have a ton of old parts and no body, either find a body that fits your parts or find a complete car. Especially if you are going to try a combo that no-one else has played with.
Put a basic short block together that won't self destruct and go to the track. A basic trans and converter and maybe not the perfect gear like you would in a Bracket car and see what it does. If it doesn't show you SOMETHING, maybe it's really not a good combo. Maybe you won't like driving a 4000-5000 LB car. If it doesn't work, get rid of the car or combo and, not a lot invested. And you can still be having fun and learning.