I have a 350 in a 84 Z28 with a TH-350. need to know what gear to use. Right now it has 4.10 but around 55 mph I'm turning about 3000 rpm. And I think that is way to much. So would 3.42 be better? Are should I go with a P275/60R15 over the P235/60R15 that is on the car now?

 

Are you using a 10-bolt? I'm personally very happy with my 3.73's. I'm turning 2000 RPM's at 75 mph and 2500 RPM's at 90 mph, with a M6 of course. With your TH350 I wouldn't go with anything over a 3.73 gear.

 

Yes I,m useing a 10 bolt. Because I ,got to buy the gears so I don"t want to get the wrong gears this time. So 3.73 should put me around what rpm with a TH-350?

 

The reason I got my 3.73's was becaue my car was an auto to begin with. For the life of me I can't remember what RPM's I was turning at what speeds. I know there's a formula but it escapes me. I'm sure someone else would be able to help ya!

 

Thanks. Hope to get more information.

 

26" tire/3.73's

60mph = 2,900rpm if there is no conveter slip. If it's a loose converter, it will be a few hundred rpm higher.

Rich

 

I'm going to be running a P275/60R15 so to run 60 at about 2400 I would need to be around 3.23 right?

 

This should help a little .