I have an 84 camaro. When I drive down the interstate at 80 mph I will be doing 3000 rpms in fourth gear. I have a 700r4 transmission and 235/60/15 for tires. When I used some of the online calculators It showed I should have 4.11 gears when running that many rpms in fourth gear with that tire size. I just had the transmission rebuilt last week with a newer core and while in the shop I had them check the rear end since I wanted a higher gear than a 4.11. They even called me and had me come and look at the gears. They were stamped 13-43 the man showed me with simple math that means a 3.23. Now with the new transmission in there I am doing right at 2900 RPMs in fourth at 80 mph. The only help someone had was that the tach might be getting a bad singal from the distrubor so I replaced the stock dist. with an MSD and also replaced the q-jet with a holley with no change in rpms.

I was hoping someone might have an idea at why this would be like this since I along with everyone I know can't figure why I am running such high rpms in fourth. I have made sure to count the gears and even drive it in drive and not overdrive to make sure it was shifting through all the gears.

Thanks

 

There is a chance your tachometer is off. They were more a decorative add-on for the car than a precise instrument, and they tend to go way off when they get older. My tach used to go to 6000+ when the actual rpm was around 4000.

 

at 80 your RPM should be 2328 in 4th gear with your 235/60-15 - 3.23 - 700R4

Ether your tach is off or the converter is not locking up.