purple78te, You cant fit clevo valves in an alloy head unless they are cut down which costs more than new valves and those sizes you quote will not fit either.
KEC cnc heads are not that good. I have purchased a few sets and they all need hand finishing to be any good which adds to the rip off cost they charge in the first place.
I get 215cfm@550" lift at 28" out of an xflow inlet port with no porting at all, just common sense.
Xflows love big carbs and anyone who says they dont, doesnt have it set correctly.
I just built a xflow with a small speedway crow cam which pulls to 5000rpm and the owner tried a 350 then a 500 and now has a 650d/p quickfuel carb and it runs the best out of all the carbs.
It is also excellent on fuel on a long run but it will increase around town if the 2nd barrels are opened often.
The crow 14806 solid cam is a dual patern cam that doesnt work the best with xflows. Single patern cams are better and will show increases in power, response and torque over simular dual patern cams.
I just advised a speedway driver to replace his 806 cam with a custom crow cam and he made more power everywhere and it comes on at 2500rpm and goes to 6000rpm where the 806 went from 3500-6000rpm. This means at slower starts which happen often, he gains 2-3 positions before the first corner as his cam comes on lower in the rpm range than the other racers.
Crow dont flow heads or test their cams in motors so they dont know all the fine points about the likes and diss-likes of different motors..
I have also ported and built full race methanol heads and there is no gain in CFM by using a larger inlet valve than a 1.84"..
Vac carbs are OK but d/p carbs are better for people looking for street/strip performance with cams that rev to 5500rpm+..
The aussiespeed inlet is the only good manifold to use for any xflow with a carb upgrade and the older cain and redlines will only give uneven cylinder fill which will lose you power and make some pots run too rich and others too lean..Unless your running 3 webers or throttle body injection, ther is no need to flow your head over 225cfm as no xflow inlet manifold flows over this but with a few mods and the right cam 400hp N/A can be made at this level..
The 8 counter weight ED and EL cranks are the best for a high reving 6000rpm+ Xflow as they do the same job as the 12 counter weight EF crank but weigh 3-4kg less. the std xflow crank has 4 full counter weights and 4 half counter weights but these are not the best over 5800rpm. The 8 counter weight crank is still used today in the FG F6 turbos but they have a different nose for the oil pump drive..
Cheers
