[rexkarr]

I'm curious what kind of performance is possible from these cars when modified? I see their size and weight as the biggest limiting factors, but considering the late 70's TA's and some GTO's weigh just a couple hundred less, maybe the playing field is a little more level than I first thought. What modifications have some of you done and what kind of results have you seen? How large of a tire can be mounted? I've been wanting to build a Pontiac V8 for over 2 years and cruising around town in my '86 Firebird these past few warm nights has me REALLY wanting to build a thumping engine.... At first I was thinking of a small light car, but I don't want to abandon my plan of buying a GP once the Firebird is gone. It would be great if it handled decent too...

Thoughts?...

[mike nixon]

I had my 72 running 12:90's in the late 80's in true daily driver street trim.

Heads, cam, gears, mild chassis work.


Mike.

[Keith Vrabec]

Can easily amke the handle well with gas shocks a good front end rebuild, front and rear big bars, and good tires. Can get really big with tires too. Steering box in GP is already pretty quick, so not much needed there, and really pretty easy to drive hard beacuse it understeers and you just keep it turning the same direction a bit as you go through the turn. (Bugatti set up his race cars like this... useless car trivia)

Yet NOBODY expects anything from these"tanks" so if you're good off the line, any stop light drag is over before it even starts.

245's fit easily and I think you can even go larger in the rear.

Build the engine to maximize torque at low rpm, easy to fit big exhaust, no leaf springs like the firebird so ride is much better.

Put the right amount of caster in it, top ball joint back as much as it goes (that's neg caster, right?) and it'll do just fine.

Nothing fancy is really needed here. DOn't find much advantage from the poly bushings, and a lot more noise with harder ride, so a neg trade off for me.

AND you can park it in K Mart without anyone messing with it.

(What did I miss)

KV

[400 4spd.]

FWIW, I've got BFG 275/60-15's on the rear of my 72.

[Ron Landis]

on the "wow" factor! My '69 GP was a factory four speed and overcammed like nobody's business. Should have seen the jaws drop when I pulled a holeshot and then nailed second gear! It was oddly enough a 400 car so the revs were pretty crazy, too...expecially for a land yacht! Enjoy...and like they said...build it for torque, since that is what moves the car.

[Sirrotica]

Basically it's the same chassis as a LeMans/GTO just the longer 4 door version of it. Anything you could do to a GTO can pretty much be done to a GP and the engine setback in the chassis is much further back than a GTO. The link below is a picture of my 69 SJ 428 circle track GP that I raced in the late 70s.

http://forums.maxperformanceinc.com/...3&d=1169772906

[cutrone]

I'm running a 295/50/15 tire on the street, lots of room still.

Having a blast with my 69 , I drive it a few times a week and drag race it often.

[Hillard]

I've owned my 69 GP since 1985. The original motor sits in the corner while I've played with a couple different combos over the years. Last motor was iron d-port headed 461. I removed the A/C (it's also in the corner although I seriously doubt I'll ever put it back on) and the car weighed 4090 lbs. with me in it. Last time I took it to the track...I drove it there, bolted on a set of worn out slicks from our GTO, (pits were kinda muddy so I left the exhaust hooked up) made it to the final round where I broke out with a 12.28. Bolted the street tires back on and drove it home.

Like has already been said...suspension is basically a GTO and build the motor for torque. Even with the long nose and short tail, they hook up fairly well...probably due to the engine set-back.

[cutrone]

Originally Posted by 1050goat

Even with the long nose and short tail, they hook up fairly well...probably due to the engine set-back.

Yeah... I always keep thinking it's like an altered wheelbase .

Dave , have any pictures of our G.P. you could post ? sound like a cool ride.

[Hillard]

It's not a very good one but the only one I could find already on the computer.

I think it's kind of a weird combo. The car was originally white, with a black vinyl top and red interior. It has manual windows, manual locks, power seat, and a power trunk. The vinyl top was already gone when I got it and I had it painted around 1989 thanks to the guy that pulled out in front of me. I got it two weeks before I turned 16. I plan on being buried in it.

[rexkarr]

Thanks for all the great responses! I'm impressed with all the room for big tires. I think 295/50/15 would have to be about 11.5" wide wouldn't it?

I currently have 2 Pontiac 400's, both are 481988 castings. I bought both complete and they're both low horsepower 2 barrel engines with 7j2 and 4x heads. Pontiac v8's are rare in my part of the country and I've been on the look out for quite a while, trying to grab anything I can. I'd love to build a stroker and I believe either set of heads could be used to make a good engine. I've been on the look out for a better set though and may be able to get a set of #96's which I think would be great for a stroker. I will have a budget though so I don't know what will be possible. I have a super T10 I'd like to use if I don't decide to use it in my '67 Impala.

What kind of gears were you guys running? I know I'm asking about performance, but honestly, fuel economy will be something for me to consider too. I'm probably not actually going to race this car, but i might be driving it on a few road trips.

[Hillard]

What part of the country are you in? I have about 40 - 50 sets of heads available.

I would recommend 3.55 gears.

[Benhm]

Had a 69 GP SJ with a built 428 in it.....man it was fast!!. Never timed it on the track, but I did have it up to 120 mph on the clock in about 15 seconds......and it was still in second gear!! That long hood started to flutter at that speed and I chickened out of a top speed trial....Ben.

[mike nixon]

I'd say 3::08-3:55's. build it for torque not rpms.

Mike

[GPCONV]

They're a blast.

[rexkarr]

1050goat, I'm in southeast Ky. If I end up building an engine and needing heads, I'll contact you to see what you have in stock.

[n2ogpsj462]

havent run my car yet and really dont care how fast it is. i know its fast. with only 6psi and a fat tune i but ran right next to my buddys 11.00 t-type. carb is setup for 10psi. should go well into the tens with a leaner tune and 4more PSI

[Keith Vrabec]

Need we say any more????

Case closed.

KV

[BOPcollector]

A buddy still has a '70 SJ 455 HO 4 spd he has owned since '72 and ran a consistant 13.90 in the 1/4 at Bradenton years ago. It is all bone stock with a/c to boot! he has it stored in a semi reefer trailer body for the past 20 years. It needs a resto now of course. I keep trying to talk him out of it.

[428ho4spd]

Originally Posted by BOPcollector

A buddy still has a '70 SJ 455 HO 4 spd he has owned since '72 and ran a consistant 13.90 in the 1/4 at Bradenton years ago. It is all bone stock with a/c to boot! he has it stored in a semi reefer trailer body for the past 20 years. It needs a resto now of course. I keep trying to talk him out of it.

Nice! What colors?

Grant