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Just bought my son a 77 SWB with a 360 auto, carter afb, duel plane 4bbl intake, stock exhaust, stock rear with 2.73 one legger, it is a gas hog (about 10 mpg or less)...considering pulling the 360 and installing a 318. Any suggestions on a gas miserly 318 build? 2bbl/4bbl, cams, induction preference? Or....is there any way to improve the milage of this 360? Thanks



The hardest part if mileage is the vehicle itself. Being a huge brick moving through the air is a problem in itself. Things I did for improved mileage to 20 MPG's in my '79 3700lbs. 360 powered Magnum were;

Open air cleaner
625 Carter well jetted, slightly lean
A stock intake was used but a RPM would be better once under power going down the road.
While I used stock heads, a rebuilt set with a good valve job to improve low lift flow would help here.
I used dual exhaust of the manifolds @ 2-1/4 inch pipe with an "H" connection into a set of Thrush mufflers.
A junk yard distributor w/vacuum advance (since in 1979 the vacuum advance was on the leanburn computer) and a MSD fired it all off.
The trans was a 904 & the rear was a 8-1/4 w/2.76 gears and 235/60/15 tires on all 4 corners.

Being a low powered emmision year engine saddled with lots of equipment, which was removed, I'm not sure if headers would help much or a larger exhaust pipe would help. More compression would increase power and mileage but I never milled my heads.