I am looking for an answer to this question about MPG as Well, My 65 Chevelle has a bit of a run down 250 in it, and I seem to be getting about 16 mpg highway miles at 50 MPH. I have a stock internal 250 with offenhauser 4 intake,with a Holley economaster 2 barrel, I think they're 350 cfm. Hei,Powerglide car, with 3.08s weighs 2900. What am I doin wrong? 16 Mph I coulda kept the 8.
So 16 MPG is My number anybody else wanna put up theirs?
Your Chevelle is pretty light.
You can improve mileage plus better acceleration if you change the rear gears & a 200R4 trans.
Depending on what tire size you use, I would suggest 3.42 -3.73 range rear gears w/an OD trans.
Also the PG glide not only suffers from a tall first gear it also suffers from the large gear gap from first to second causing your vacuum to drop more between gear changes while keeping the pedal in the same position. (Puts more load on your engine)My moms stock 73 4 dr Nova had a PG & 3.08 rear gears, 26 " tall tires.. It ran fine day to day driving, great on the freeway.
Normally it would get 16, until I started working on it & advance the timing, then it whould get 18 - 19 tops MPG, all stock were talking here,w/90,000 + mileage.
It got a best of 19 MPG on the freeway, but that was above the speed limit speeds.
I estimated the Nova weighed 3400-3600 lbs.
A TH350 would have been better for it & a 200R4 would have been better though the first 3 gears, OD, with 3.08 is too much for just cruising @ 65,OD would have been use when going 85 + MPH
MBHD
