Thread: Rebuilding a 292 for mpg

Tweet

I think you are on the right track with the quench and bumping the compression up. Is that .041 quench with zero deck pistons? The 390 carb should work too. Is the intake a long and narrow runner type? That would optimise lower rpm torque and increase mpg too. Those small valves will be dandy for higher port velocity too as long as they aren't the choke point. Polish the combustion chamber and maybe coat the piston tops too. I think Speedway has some ceramic spooge for that. You can look into some of the tricks that the emissions cars have been using for economy like electric fans and running a tad hot plus the cam grinds too.

Originally Posted by w2zero

I think you are on the right track with the quench and bumping the compression up. Is that .041 quench with zero deck pistons? The 390 carb should work too. Is the intake a long and narrow runner type? That would optimise lower rpm torque and increase mpg too. Those small valves will be dandy for higher port velocity too as long as they aren't the choke point. Polish the combustion chamber and maybe coat the piston tops too. I think Speedway has some ceramic spooge for that. You can look into some of the tricks that the emissions cars have been using for economy like electric fans and running a tad hot plus the cam grinds too.

The .041 I'm figuring is with a .025 steel gasket and pistons .016 down. In the Y-block world the 1.92 intakes are large, as are the intake ports on the heads and intake runners on the manifold. Actually I think poor port velocity is a main problem now, caused by the mismatch between cam and compression, which in turn pushed me to a small 2V carb after trying a 600 4V. But hopefully that would improve a bunch with increasing comp.
The combustion chamber polish and piston top coating: is your thought there to deter detonation at 9.5:1?
There is an electric fan and fuel pump on now.
I really dont know what an appropriate cam would be. The 260 duration and .420 lift is just something that is less horsepower oriented than mine, but more so than stock. I figured (right or wrong), that decreasing the duration would increase port velocity.

Yep, 260 is the mildest cam Isky grinds for that motor. Should work great with the 9.5 max c.r.

http://www.iskycams.com/onlinecatalog.html