Originally Posted by 360view
Originally Posted by Guitar Jones
Originally Posted by HotRodDave
What gears are in it?

4.10s with a 31" tall tire. It has on paper a 8.9:1 compression ratio and a small 220/220 @ .050 cam with .478 lift and a 108 LSA. Heads are bone stock Magnums and the engine is .040 over. Edelbrock Performer RPM air gap intake and a 1" carb spacer. It has light spark knock under moderate load on 87 pump swill. I've knocked the timing back to 28° total at 2700. I don't want to go any farther.


with that gearing and aerodynamics that MPG is not out of line,
especially if parts of trips are off road and on hilly country roads


sometime in the future use an oxygen sensor to find out your “ballpark” air to fuel ratio at level highway cruise



That timing curve is waaaay too conservative for that motor. It should not be anywhere near spark knock, maybe you have a fuel line too close to exhaust somewhere or insufficient air flow under hood or something. That engine should easily take 32-35 degrees mechanical timing and that would help MPG quite a bit. I would try bumping the timing to 35 and run premium through it a couple tanks to see if it is worthwhile to run premium by getting much better MPG. I had a nearly identical cam in a magnum 410 iron magnum headed stroker motor with 11 to1 compression and it would run 32 degrees timing on premium with no knocking.

I am not causing global warming, I am just trying to hold off a impending Ice Age!