ratio ???

[bjmoore]

My 84 k10 has a 4 speed (granny gear, bull dog whatever you would like to call it). A stock 305 and 35 12.50s. Was wandering what would be a good gear to use for a mostly street truck. The little 305 pulls it pretty good but the stock gears are just to high. Wandering if anyone has been there done that. Experience is worth a lot from someone that has already tried it and come up with a good set up. Thanks guys....

 

[firebane]

What do you currently have for gears in the rear? You say they are too high... High gears would be like 3.08 gearing

 

[bucket]

Do you drive on the interstate much? If yes, I'd do 4.10 or if you don't spend too much time on the freeway, 4.56 would be a good choice. That little 305 needs all the help it can get.

 

[bjmoore]

Not much interstate running . Mostly just two lane country roads. Good I was thinking 3.73 just for a guess. Was wandering about a 4.10 was afraid it would be to much gear and I would be turning my poor little 5.0 a ton of rpms with even worse mpg. I guess around here the lower gear would probably help mpg. May not have to be floor boarding it all the time. Thanks

 

[crazy4offroad]

2,755 rpms at 70 mph with 4.10s. If you wanted to run 3.73 it would cut it back to 2,507 rpms. Running backroads at around 60 mph 4.10s would be 2,362 and 3.73s would be 2,148.

 

[bucket]

If that little 305 is in good health, 4.56's won't hurt it. MPG may be the same even at a much higher rpm, due to less engine load.

 

[bjmoore]

Thanks for the info guys. Not to change the subject mid thread or anything but how do you recalibrate the speedo with the new gears and tires. I have done it on countless mustangs but never tried it on one of these. Thanks again. ..