[STXJudge]

I have a problem, where I've managed to collect a little money, so my GTO is ready to take care of that for me. I haven't settled on a cam or a rear gear ratio yet, so I want a little help sorting that out. I still have the 10 bolt rear, and I need to swap to a 12. As long as I'm changing it, I'm up to changing gear ratios while I'm at it. I have a T56 6-speed moving a 3900 car (with me in it), currently running 4.11s. I'm not worried about these being too tall, 6th gear makes them driveable enough for me. (2100 rpm @ 70mph) I don't know where to go to get a well built rearend, or what gear ratio I should install in it. I also don't know how that would work with a cam recommmendation for my 455. I'm not deep enough in my engine that I can't change anything I've already done, so let me sum up. 3900 lbs, 455 std bore, ported 6x heads, 9.6 CR, Hooker headers, 2.5 exhaust, 750 cfm Edelbrock carb, will have performer intake. Frequently street driven, I'd like just a little bit of lope, which cam, which gears, where to buy the rearend? If you have input for any other aspects of my project, please let me know, this is still my first attempt at anything remotely like this.

[STXJudge]

I have a problem, where I've managed to collect a little money, so my GTO is ready to take care of that for me. I haven't settled on a cam or a rear gear ratio yet, so I want a little help sorting that out. I still have the 10 bolt rear, and I need to swap to a 12. As long as I'm changing it, I'm up to changing gear ratios while I'm at it. I have a T56 6-speed moving a 3900 car (with me in it), currently running 4.11s. I'm not worried about these being too tall, 6th gear makes them driveable enough for me. (2100 rpm @ 70mph) I don't know where to go to get a well built rearend, or what gear ratio I should install in it. I also don't know how that would work with a cam recommmendation for my 455. I'm not deep enough in my engine that I can't change anything I've already done, so let me sum up. 3900 lbs, 455 std bore, ported 6x heads, 9.6 CR, Hooker headers, 2.5 exhaust, 750 cfm Edelbrock carb, will have performer intake. Frequently street driven, I'd like just a little bit of lope, which cam, which gears, where to buy the rearend? If you have input for any other aspects of my project, please let me know, this is still my first attempt at anything remotely like this.

[fasteddy]

Get the twelve bolt package deal from Moser for the A-body in a 3.73 or 3.90. Use a RA4 profile or a Comp hydraulic roller 238/242 @ 50 if you have the extra dough. Just my opinion.

[rumair]

forget the 3.73's or 3.90's, getcha some 4.30's!!

if you wanna stick with a hydraulic cam, i'd recommend the comp RAIV grind.

[STXJudge]

Is 4.30 decent for a 2.66 1st gear? Or will I end up shifting just one second off the line. Will the 3.73s or 3.90s seem too low for a .50 6th gear? Does Moser sounds good to everybody else? Will the RAIV cam give me a little bit of attitude at idle in a 455? I'd like to get as many opinions as possible. All that I know about these things is theory, I have yet to play with any of it myself. Thanks for the input so far.

[77TA406]

Unless you are stuck on swithing to a 12 bolt diff, don't underestimate to strength of a 8.5 inch 10 bolt. They can be made to handle a LOT of power. A good friend of mine is running his 4000 lb street trim 76 TA well into the 10's @ 128 with a 10 bolt...granted, his posi needs to be rebuilt every now and then, but the diff stands up to the abuse. Just my opinion.
Chris

[78taman]

I can buid you a 8.5 rear end with 3.42's or 3.73's that will work in your car. The only thing you need to do is shorten the driveshaft 1 inch. My Father has run an 8.5 in his 64 GTO that runs in the mid 11's for 4-5 years with no problems. I live in north Texas, my email is [email protected] or you can call me at 972-578-0012.

[STXJudge]

Well, if it seems like I can stick with an 8.5 for a while, then I'll just use the one I've got. It was rebuilt about 1500 miles ago, and has Richmond Gear 4.11s in it. Will the RAIV came give me the feel I'm looking for, and the consensus seems to be that my 8.5 will hold up to that just fine until I can put some really serious power into it.

[Thumpin455_GTO]

You should have an 8.2 rear unless it has been changed. They are different from the 8.5 that came in 2nd gen Birds.

I have a 455 that is very similar to yours in my 70 GTO. Ported 5C heads, RPM intake, Demon 850, 2004R trans, 12 bolt with 3.42 gears. Unless you have an engine that needs to RPM really fast like a small chevy does, you dont really need much more than 3.70's. I actually picked up ET and MPH by switching from 4.11's to 3.42's in my Bird that also had a stock rod 455 but with ported 670's.

Cam choice go for something about a RA IV with Rhodes lifters or something simliar to the Summit 2802 cam. I have been running ultradyne cams in mine, a 280-288 in the GTO and used to have a 288-296 in the Bird.

You wont use 6th much anyway unless you go to a 4.30 gear. 5th is more than adequate with a 3.42/3.55 gear. Plus you wont be shifting before the 60ft mark. To each his own, in the end its your car. I just tell people what has worked for me and how well it works.

[russ467]

I feel that at this power level, even if the 8.2 is still in the car, it should hold up. I would worry more when the car runs quicker than a 1.60 60ft time.

[wyldgoat65]

78taman,
Thanks for the reply but have acquired a rear end.

[bmpmdf]

At 3900lbs, I think following Jim Hands example would be a very good package. Your benefit is with the stick, you won't have the drivibility issues an auto has with stall convertors. With properly done 6X's, and good shifting the RAIV or the other cam Mr. Hand used would be a really nice running car. I would think low 12's would be like falling off a log.

[bmpmdf]

Oh, with the stick, I would stay with your gears.

[STXJudge]

So it seems like the RAIV cam is a pretty good way to go. The Comp Cams website recommends their #995 springs with that cam. Will I need to have the spring surface of the heads machined for those springs?

[BB1968]

I too beleive the RAIV cam is the way to go. I put one in a basicaly stock 400 and it really woke it up. I used lunati lifters and a good double roller gear and chain. I did have a turbo 400 with a stall and I need it. Real nice lope and good performance. I still have the original 10 bolt in my 68 GTO and it has held up to anything I wanted to throw at it. I am new to Pontiacs, but it has been an awesome experience from sbc's.

[J.C.you]

i would weld the axles tubes to the carrier whatever rear u use. snatching on that stick may break ur spot welds aloose, especially if u put some slicks or stickies on and it hooks hard at that heavy weight.