My original vision for my '70 was a 2 block screamer and I got more than I bargined for. 383 makes gobs of torque, the 4.10's really spit it out but it is far too much for the stock 14 inch wheels and fairly narrow tires. SINCE I will keep the engine and will not budge on the wheels and I want a livable cruise RPM what should I be shopping for ratio wise. I have the stroker, a TH350 with a strong shift kit an extra clutches, a posi rear and tires will yeild a nearly 26" diameter. I would like to keep my 55 cruise revs below 2500. Right now the combo reaches 3rd gear waayyy to quickly. (The smokey burn outs at half throttle are cool though) Anyway. . .I know there is a method for calculation. I am thinking 3.23 but that may not be enough of a a reduction? Any guidance appreciated or if you can point me to a resource I may be able to figure it out by myself.

The best way I know to get you where you want to be it to use the "performance factor" @ oscaracing.com. They have a deal set up where you enter you tire size and gear ratio and it will tell you what rpm vs. mph.

I have 3.42's w/26" tall 295-50-15 Radial T/A's. Rpm is about 2,500 @ 55. Calculators say 2412, but with converter slip....

But don't expect it to improve the wheelspin problem much with those skinny tires, my mild 400 can spin the 295's all through 1st.

Angel, not worried about the wheel spin, it is a good thing since I'm not racing. Maybe I grab some 3.08's?

I would go w/ like a 3:23. You dont want to go too tall or it will feel like crap after running the 4:10's. I run 4:10's w/ my BB so I know all about the half throttle smokey burnouts (hell mine are 1/4 throttle) on street tires. But if I were you I would go 3:23 or maybe even like a 3:42 and get some decent 15" rims and tires. It will keep your car fun to drive. I personally would hate to have a highway gear in my hotrod.

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454 BBC, Turbo 400, headers, cam, 4:10 12 bolt, etc.

[This message has been edited by 70RATZ28 (edited November 05, 2003).]

70 Rat, you have a good point. What I should really do is get a T56! Can't do that right now after all the money I spent getting this far! I'm pretty sure that with highway gears it will still spin and spin!

I have a set of 3.42's in my parts car's 8.5" if you want to trade and have a 8.5".

I've saved some of the best articles from my Chevy high performance's. They've got some great tech stories. Here it comes:

ENGINE RPM AT A GIVEN SPEED:
mph X final drive ratio X 336 / tire diameter = rpm

or TIRE DIAMETER:
mph X final drive ratio X 336 / rpm = tire diameter

final gear ratio = axel ratio X the highest transmission's gear

good luck, David

My brother used to have a Monte Carlo w/ a fairly stock 350 and TH350. I don't remember all the spec's of the car but I know the rear was holding 2.xx, not sure. Anyway, with those "highway gears" and 14" stock tires those wheels would spin thru 3rd gear. Once they lit-up they wouldn't stop until he did. I think they were spinning way too fast to EVER get traction until the car would catch up to tire speed. Heck of a light show.

[This message has been edited by shzaz28 (edited November 06, 2003).]

see my sig. similar setup. I went with 3.42's and they are very street driveable. I have 245x60-15 tires and I can still lite 'em up with just a little tap when I'm in the mood.

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Steve. 74 orig owner
383, Comp 280, Sportsman II, HD TH350, 3:42 posi, 4wdisc, 12:1 box, IAS, headers, true-dual w/H-pipe. All new susp/bushings.
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Long Island Phantom Hockey -23-

OR....
just put in a T-56 like me. I get over 20mpg with my 4.10 gears and a Holley DP, but I can also drop it a couple gears and chirp the tires if the rice rockets are calling for it. I'm not sure how much original you want to keep the car.

Eventually I REALLY want a T56. Unfortuantely, I did a frame off resto on this car in a year and devoted too much money to it for now. Give me an idea where you got your 56, how difficult the swap was (bellhousing, pedals, clutch etc,) AND the total cost!!! Thanks this is the main reason that I will not offer up my 4.10 Richmond set on a trade. I want to keep them and use a 56.
Brent

I bought the LT1 and T56 a few years ago. I think I paid $3500 (off ebay, guy nearby where I lived) for everything I wanted off the 96 Firebird with 10,000 miles on it. I detailed the installation on my website. The link should work up above. Since then the LT-1 is gone, and I mounted the clutch actuator better. I don't have the newer pics posted yet.

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1981 Z28
350 Vortech Heads, 268XE, 650DP, 4.10, T-56
The last thing they see on my car when I speed by is my TRAILER HITCH :^D

"The Surgeon General never said anything about smoking the competition." Toyota ST185 ad