[70lemansport]

Hey,

Ive got a 70 lemans convertible (if it matters) that is getting a rebuilt 350 bored .40 over with about 9:1CR and a summit 2801 cam and pocket ported heads. Im thinking that since in budgeting about 200-250$ for a Torque converter im gonna go with a TCI breakaway(about 23-2500 stall). next question is rear gear. Definatly doin a posi but am debating with 3.55 or 3.73(possibly a 3.23 if i can be convinced). I want GOOD get up and go and it will see the track some. mostly a cruiser for around town and the occasional freeway journey. mileage is no consideration (and im 19 so i wanna go fast). So what would you reccomend?

Thanks guys.

[goatless]

For a car that will see mostly street cruising I would not go above the 3.55. If you had a bigger motor I'd even recommend going lower like the 3.23, which even so would still be pretty good for your intended purposes.

BTW, I'd recommend a Hughes GM25 torque converter over the TCI any day and is still very reasonably priced.

[Brandi Kay]

3.55 is good, i agree. It will get up and move for sure!

[prostreet64]

If the rearend is the original GM 8.2, Pontiac/27 spline pinion, I think your gear choices will be very limited. Richmond and some of the others only list 3.55, 3.90, 4.11. If you happen to have the newer 8.5 corporate rearend, then 3.42's or 3.23's are available but not the 3.55's. In any case I wouldn't recommend anything over the 3.55's.

[OINK 1]

323- great highway
355- really nice for highway and around town
373- quicker off the line, ok highway

I'd get 355's and an 11" convertor.
Change that JUNK CAM !!
Get an Ultra-Dyne 280-288 h 12+6 $155.00 from me.
Or Comp 51-223-4, 268-280 h10+4 $ 118.00 from me.

Pontiac Gregg
1-303-776-0877
Web site:

http://www.pontiacengines.net
click on cams, has tech data with each one.

[70lemansport]

I cant use either one of those with my pressed in studs. Max lift i think i can use with stock rebuilt heads .470 and thats pushing it. The summit won over because of the 100$ price for the cam and lifters. And that XE268 is pretty big for a 350. I dont think id have much torque down low with that..

[dmac]

if you want speed go 3.23 if you want acceleration go 4.11. You say you want to go fast. The lower the number the faster you will go, the higher the number the faster you will accelerate but have lower top speed and lower mpg. with 3.23 you will have plenty of both for the street. Those cars came with 2.73(?)s usually and with 3.23 you won't be tearing up the rest of the suspension, and wearing tires as fast. And you will still be able to really go fast if you need to. The difference between 4.11 and 2.76(?) is like 9mpg max to 15 mpg. It does make a huge difference in how far a couple bucks of gas will take you on a Friday night. I vaguely remember trying to scrape up a little gas money when I was 19, and always had something else I'd rather spend it on. Good luck however you decide.

[hal101]

i vote for the 3.23

[Airic1]

I would recommend the 3.73 gear in the rear. Gives you more options for future upgrades.

Eric G.

[Steve Barcak]

I know you said milage doesn't matter and such but....

Try to think a little further down the road..
1. How long are you going to own this car?
2. realistically, how many miles a year are you going to put on this car?

If either, or both answers are relatively small, stick with the advice above.

However,
If you want to be really able to drive this thing, really enjoy it and really be able to put some serious miles on it. Think differently.
Use a 700r4 trans and a 2.73 or 3.08 rear.
Here is what this will give you over your 350/400thm and 3.55 set up.

You will have a much deeper 1st gear in the trans. This will give you all the acceleration and more than the other set up with 3.55 or lower gear.
You will also really be able to drive this car.
What is the speed limit where you live?
Many places it is 75mph. that means you can usually drive 80mph and not be bothered.
3.55 and lower gears have no place on the hiway.
Not only from a mileage stand point either... It is much harder on the motor, it is spining higher for long periods, It will also run hotter

If you use a Over drive trans with a very mild gear you will reap all thebenefits- outstanding acceleration, higher practical top speeds and cruising speeds, better mileage and, most important, you will like the car much more and end up driving it and enjoying it much more.
A second option is to your trans but, install a lower planetary gear set in it. This will give you a lower first gear for better off the line acceleration and allow you to still have a milder rear gear without compromise. I have a few hundred thousand miles with pontiacs using this set up.
Plan wisely and you will enjoy your car more and you do not have to give up acceleration.

I am surprised others have not suggested this.
good luck with it.

Steve

[slowgto]

For a heavy convertible, a 3.23 isn't quite enough gear for the results you want. Go with the 3.55. I have both a '70 GTO convertible with a 3.23 and a '69 hardtop with a 3.55 and the 3.55 geared car is the one that feels strong.

[uforacing]

I do have one question that has not been asked. What size tire are you going to run in the rear?

[70lemansport]

I dunno to be honest. Got a set of vintage ansen sprints in the 15x8 flavor from my nieghbor about a week ago for 30 bucks so i havent gotten that far. Probably a 255 or 275 55 series tire.

[440GP69]

XE268 is a Tiny cam in a chevy 350 let alone a Pontiac !

[70lemansport]

Well maybe once i get some worthwhile heads with some screw in studs and the right valvesprings i can step it up to that one. I was lead to beleive it was big but maybe they were only talking about for my application. Thanks for the schoolin.

Totally off topic but if anybody using camquest from compcams..Would an edelbrock performer count as a standard flow or high flow dual plane maifold where maxflow is the highest?

[Thumpin455_GTO]

Im with Mr Barcak on this one. Highway gears no deeper than 3.55 and an OD with the deep first gear if you dont mind the adapter plate, you wont break a 2004R with a 350 and you can use the stock converter with any of the cams listed. Get some 6X or 5C heads, they arent that hard to find, both have screw in studs and large intake valves.

You are only 19, that means you probably dont have a pile of cash. That also means you can learn to do the work yourself and save some hard earned $$. If you learn to build automatic transmissions, you wont ever have to pay someone to do it for you in the future. Learn to swap gears at the same time, like in a Community College course and you will have something to fall back on later in life. Those are the two things most backyard/shadetree types cant do.

I would go with 3.08 and a 700R4 and 27-28" tires and the UD280/288. Thats just me though. I really like that cam, Ive run it in 400s and 455s and it idles like stock while making enough torque to rip the tires off at 30mph with 2.93 gears. I wouldn't be opposed or concerned about it in a 350 with 6X heads. The highway gears are nice when you are driving normal, and hardly a detriment when you are racing provided you make some torque.