i am having to replace the valves in my heads the heads have already been ported should i use 2.02/1.60 or 2.00/1.56 i have a hotcam now but may put 1.7 rr on later so what size valves would be best for street driving?

 

The best combination on my ported heads I found through testing on a flowbench was 2.00" Manley RaceFlo intake valves, and stock exhaust valves. The comparison was Manley RaceFlo 2.00" intake and 1.56" exhaust vs. stock valves. The 2" Manley intake valve outflowed the stock intake valve, and the stock exhaust valve outflowed the Manley 1.56" exhaust valve.

I think a larger exhaust valve gets too much shroud in the combustion chamber, and since the stock exhaust valve is smaller it doesn't suffer from this as much. And yes, I did open up the chambers around the seat and also worked on unshrouding it, but the stock exhaust valve still flowed better.

Stock exhaust valve flowed a peak of 3.2 cfm more than the Manley counterpart at .400" lift.

Manley intake valve flowed a peak of 6.5 cfm more than the stock counterpart at .300" lift.

 

i can't provide any flow numbers or tech info, but i can say that 2.02/1.60's made a badass out of a hotcam. guy around here dynoed around 380rwhp and much over 400rwtq. this particular car sounded like a 306 grind rather than a hotcam. very wild sounding hotcam. one hotcam car i wouldn't mind having

 

i went with the 2.02/1.60 manley race flows and i doubt the 2.00/1.56's would get me close to where i am now. you will have to have them install new seats though and if i did it again i would go 2.05/1.65

 

well I think I will get the 2.02 1.60, manley race flow , they look like a good valve. thanks for the input

 

Sometimes I wonder why I even bother replying

 

dude, what kind of bottom end setup did this guy have to put out over 400rwtq?

seems pretty irrational with just a hotcam (or with a stock bottom end setup in general). but thats just my opinion.