Another mpg question...

[Crusty75]

Did a small drive today to check current, as is mpg with the bone stock 8.5:1 350 with only a slightly upgraded cam, and it pulled 18mpg... Not bad at all...

With that being said, what kind of gains can I expect to see with the increased compression of the 416 heads and a good set of headers, and possibly an intake? The Quadrajet will be staying on the car

 

[Cataldo]

I would expect 1 to 2 mpg at best, but with notably better power. If you gain 1 mpg but have to switch from regular to premium it will cost the same to less for the better power sound and throttle response (so it is a win win).

Your gains all will be determined by hoe good your stuff is now, and how restrictive it was.

 

[tom3]

Not sure but I think the 75 Qjet has the external adjustment for the metering rods? Have to pull off a cap to get to the adjustment but you can drop the rods a bit and pick up a couple mpg - sometimes. too lean and you'll feel it on light acceleration, usual factory setting seems to be a bit rich to cover the bases.

 

[Crusty75]

If I can pick up 1 or 2 mpg from the raised compression I'd be a happy camper, even if I had to run 91 octane in the car...

How can timing affect MPG? Can I adjust the timing a couple of degrees and gain a mile or so? How about plugs?