54 Chevy 2 door post rear gear.
 

I am slamming my 54 210 post back into a modern safer daily driver.

1979 Buick 231 V6, slightly ported heads, gasket matched heads/Edelbrock intake, hei with weight kit, th200r4, and a Isky mile a mor cam. The rear tires are 245/45r17. Or 25.5 inch installed height roughly. Daily curb wieght with me ,and my son in it should be just under 4000 pounds.

Cam specs.

Valve Lift Int/Ext. 0.425/0.425
Valve Lash Hot Int/Ext. 0.000
ADV Duration Int/Ext. 248/248
0.050 Duration Int/Ext. 194/194
Lobe Center 108

So which gear ratios would you Vote for.
Cruising rpm defined as 75 mph to keep up with traffic easily.
3.89 gears with a 2589 cruising rpm.
3.73 gears with a 2470 cruising rpm
3.55 gears with 2351 cruising rpm


I am leaning to the 3.91's for better street manners. As that would be most of it real day to day. I currently rarely hit the freeway except to go on a trip litterly. Plus the factory straight 6 used 4.11's with its overdrive trans, and slightly taller tires.

Re: 54 Chevy 2 door post rear gear.
 

I too like the 3.91's for this application! It looks like it will drop you right into the heart of the torque band if you shift between 4,000 and 5,000 RPM while still returning a decent freeway RPM at 70-75.

Re: 54 Chevy 2 door post rear gear.
 

Moving post to Alternate Tinkering section

Re: 54 Chevy 2 door post rear gear.
 

This ratio calculator link should help you make the right decision.

Your combination will be similar to a first generation S10 as far as torque and weight. The 4.3's came standard with 3.42 in a 2wd and 3.73's in 4x4 spec. Although the automatic transmission was a 700r4 which has a 3.06 first ratio compared to the 2004r's 2.74 which made them seem peppy. The S10's also came with taller tires than your planning.

https://www.blocklayer.com/rpm-gear