Polishing intake on 4.0
#1
#2
I have not tried this on the 4.0, but in most cases the intake passages are best left as cast to retain some turbulence to keep the air-fuel mixed well. The point where performance can be gained is in matching the size and shape of the manifold-head juncture. Go ahead and polish the exhaust ports, but don't make the port too big or you will lose velocity.
#3
#6
#7
You polish the combustion chamber and the exhuast port, just open everything else up.
To get to the 40hp mark you need to do more than a gasket match. Porting is a skill at least if you plan to make horsepower it is. There is a reason places charge 1600 for a set or ported and polished heads.
To get to the 40hp mark you need to do more than a gasket match. Porting is a skill at least if you plan to make horsepower it is. There is a reason places charge 1600 for a set or ported and polished heads.
#8
#9
You better off swapping a 5.0 and P&P those heads you'll gain more than a 4L you also can run a carb instead of EFI
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