ColbyG,
it would certainly help if you knew what camshaft you had in the engine. Camshafts are developed for different load ranges across a given RPM band, you wouldn't want a race developed cam in a truck used for towing. Typically a SBC starts to make power at 1500-1800 RPM, with a midrange power band of 2400-3000 RPM. With an overdrive as high as you are considering it could drop the engine down to 1600-1800 RMP at speed. This setup would be fine on a flat open Interstate, now through in a few hills and your doing a lot of down gearing.
As an example, my 327 was built with a higher RPM cam (2200-6400 RPM), with a 3.08 rear and 27 inch and final drive of 1.00 my RPM at 65 MPH would be around 2500 RPM, change the rear ratio to a 3.42 and now were at 2750. Keep in mind that I built my engine for around town (traffic light to traffic light) and an occasional trip to our local drag strip.
The key to this is knowing what RPM range your engine was built for. It's time for HRL (Jerry) to come in and provide some knowledge.
Last edited by TUTS 59; 07/30/2021 12:07 PM.
