Gear Ratios

[gonzo64]

Ok, I don't know much about gear ratios, etc. My 64' orginally had a 230 straight 6 with a three speed tranny. The rear end has never been messed with, so it is all stock. I just dropped a 305 V-8 in with a 350 turbo automatic transmission off an old El Camino. In town, it runs great...quick off the start, good acceleration, etc. However, on the highway, it is so wound-up, it feels like it's gonna blow. I can't go much faster than 60 mph. It really makes me feel stupid when a Geo passes me on the interstate! What is the best way to fix this (nothing radical, keeping a budget in mind)? Can the gears be changed out? If so, what to? Should I go with a different differential? Would 4:11's be my answer? I have no clue. This is my biggest gripe.

gonzo64
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[ftyler]

3.08 gears would do you good. You'd lose quite a bit off the line, unless you go with a 2000+ stall converter. But depending on your tire diameter, you could loaf on the interstate as low as 2400 rpm at 70 mph. That's a pretty picture.

There are several things you can do to accompany this. The easiest would be to find a 6 lug 3.08 rear axle of the same width and of same type suspension. Finding one in good condition is not an easy task.

Of course you could just get the ring and pinion gears and play around with that but you'd better know what you're doing with the shims.

My personal choice, since you've already gone with an automatic, would be to change the th350 to a 700R4. You'd get even better off line acceleration than the th350 PLUS overdrive for nice cruising rpms on the interstate. It's the most expensive option.

-ftyler