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Discussion Starter · #1 ·
Hello to all, first ever post! Picked up a 70 torino w/351c-4v from my brother-in-law. It's my mid-life crisis! Car has radical cam, 2500 stall converter and c4 automatic. Original rear-end has 3.00, brother-in-law says I need 4.11s in back to really enjoy the engine. He says it needs to run at higher rpm to function correctly. I drive it around town, weekends, etc but have no plans for taking it to the track! Thoughts...4.11, 3.89,..? Any help would be appreciated.
 

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That's a pretty heavy car and a 351 C with 4bbl heads isn't all about low end grunt so some gearing would help.

What size rear tire? Tire height makes a big difference. Any idea what cam it actually is?

Since you aren't thinking about racing I would say a 3.70 may be a good choice for say a 27" tall tire. It would feel pretty quick around town but the rpm would be bearable on the road. A shorter tire you may only want a 3.50.

3.89 or 4.11 may be a better track gear but with the 1 to 1 top gear of the C4 you better get used ot rpms all the time. Sounds like you just want to cruise it and occasionally burn some rubber or feel some acceleration.
 

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Hello to all, first ever post! Picked up a 70 torino w/351c-4v from my brother-in-law. It's my mid-life crisis! Car has radical cam, 2500 stall converter and c4 automatic. Original rear-end has 3.00, brother-in-law says I need 4.11s in back to really enjoy the engine. He says it needs to run at higher rpm to function correctly. I drive it around town, weekends, etc but have no plans for taking it to the track! Thoughts...4.11, 3.89,..? Any help would be appreciated.
heres a tool that might help:

Gear Ratio Calculator - SummitRacing.com
 

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Discussion Starter · #4 ·
Thanks for the input. Rear tire height is 27". The only thing I know about the cam is that it is a Comp cam that is "fairly radical". It does have a noticeable lope to it that sounds great. Using the multiplier, @70 mph the 3.7 gears give rpms listed as 3,223...for the same with 3.89 gears, the rpms are 3,388...and for the 4.11s it goes up to 3,580. The math makes sense to me, but I don't know enough about cars to know how much is too much? Fefairlane is right, I just want to cruise around town and burn them when I need to.
 
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