Chevelle Tech - View Single Post - Gas Mileage Test 5 speed vs 6 speed
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post #8 of (permalink) Old Oct 21st, 19, 5:10 PM
jeff swisher
Senior Tech Team
Join Date: Jan 2008
Location: yukon ok.
Posts: 5,251
Re: Gas Mileage Test 5 speed vs 6 speed

1969 350" in 1957 4 door 3650 with driver then add a 20 foot pontoon boat.
Yukon OK to Texoma on Texas side 190 miles.
Averaged 11.5 MPG.
I August of this year with AC on and 1969 350" Ported 601 heads 280H magnum flat tappet RPM intake and 750 Edelbrock 1407. Recurved 1978 HEI.
3.70 gears NO overdrive TH 350.

Yea not a BBC.
Drove a Dually tow truck I stuck a 454 into, had granny 4 speed and 4.11 gears .. pulling a car for 1/2 the trip.. mostly city I tuned it to 12 MPG dropping the APT adjustment on the Quadrajet and Recurved the HEI.
Before APT adjustment and recurve it would get 6 MPG.

I feel the Andrews 68 Chevelle could have got better MPG if he was a little leaner in the cruise.
My part throttle cruise from 2200-3200 rpm cruise is in the 14.5 area and 18 MPG is the normal on highway.

But maybe his car does not like that..I am sure he has thought about that or tried it though.
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