Hi Mike,
It depends on the overall engine design. The in & out need to be
somewhat balanced. What can't get out can't get in & vs. Usually the
exhaust needs to flow about 70% to 80% of what the intake flows. Some
folks believe that the original exhaust valves/ports are
disproportionately restrictive. I have certainly not found any
disadvantage to this modification.
Dave Russell
Bn2
Mike MacLean wrote:
> To all that answered my question about what size exhaust valve to
> use in my 4 cylinder head because of the oversize seats, 3000 valves
> fit perfectly. Some suggested just that, but I always thought if you
> wanted more power you used bigger intake valves. What kind of a
> performance gain do you get from bigger exhaust valves only? Mike
> MacLean 56 BN2 60 AN5
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