Dont you think 1mm is a bit small for a valve increase on these motors? Dont you use the stock seat at just 1mm oversized? When I got looking into the head I noticed that the exh valve seat was quiet a bit smaller than the bowl but that was not the case on the intake side. I was thinking that increasing the seat size to mach the bowl would be better but that would take 2-3mm over sized valve right?

7mm difference between intake and exh valves seems like a lot but I havent bothered to measure these kinda things on any other motors I have worked on.

I asked on the other thread about any sort of industry standard when it comes to the ratio of exh valve to intake valve size? Is there any reason we couldent use an intake valve and seat in place of the exh valve? Would it work with the engine dynamics barring any clearance issues with water jackets in the casting?


Averkam....
The larger than normal gains on exhaust work I think are due to porting the heads and intake along with cams and headers. once that was all done everything was flowing better except the actual exhaust tubing it was still stock 2" w stock muffler. Once that was opend up it allowed everything else to do its job. I cant wait to have my throttle body bored and cut up a manifold to see what can be had in there.