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Discussion Starter #1
I own a 1970 Mach 1 and would like some more go out of it. Right now he gearing seems to be higher than the stock 3.00, as it only turns the wheels about .8 times per 3 spins of the axle. It has a C6 with a high stall and the engine itself doesn't really make much power low in the rpm range due to a big cam and the fact that it is a Cleveland, albiet a 2v. Would 3.50 be a good ratio to use instead of what I have now, and besides the gear and pinion, do I need to change anything else
 

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I run a 3:50 gear in my 351c 4V with a wide ratio toploader. I like the gears and they are acceptable for highway use. But if I had a 5 spd I would run 3:91 gears in a second.
As you know Clevelands like to rev.
While you have it apart have the bearings checked and if you have limited slip the clutch plates. You will also have to reset lash and replace the pinion sleeve as it crushes to set depth when you tighten it.
 

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first off, a high stall converter will make the car sluggish at the line under normal street driving conditions. Unless you race a lot you might want to go back to something closer to stock.

Second, 3.50 is an OK street gear for around town, I wouldnt go on long trips at hiway speed for long. Its worthwhile if you dont go on long trips. All you need to do is swap out your 'chunk' for one with a 3.50 gear installed.
 

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Discussion Starter #4
I should mention that the car has a locker I suppose. Both tires spin, even around corners. I did not install it, it came to me that way. The car is just for fun around town, not for long trips. It might, MIGHT, drive 15-30 miles on a nice sunday afternoon.
 

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Since your car is an "around town car", why not go with something around 3.70 and really feel the punch! For a car driven long distance to shows, etc., I wouldn't go any steeper than 3.0 When I switched from 3.0 to 3.25, I absolutely hated the highway cruising RPMs, with my 351C-2v. Now that I have the T5-Z, I have a craving for A LOT more gear!
 

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If your longest trip is 20 miles, put in 3.91 or even 4.11. I have 3.89 gears behind my 351C-4V in my 73 vert, and I have 4.10 gears in my 67 GT350. I don't plan on driving them out of town, so what the heck? With the sluggish bottom end a Cleveland has you need a lot of gear to get it rolling(especially if you are running 15" tires).
 

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Wait a minute - "it only turns the wheels about .8 times per 3 spins of the axle". You mean you turn the driveshaft 3 times and the wheels only turn 0.8? If so, you have 3.75 gears (or thereabouts). Or am I missing something?
 
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