Hey guys I have a question....I have already bought a set of PEP 2.02/1.60 valves for my LT1 heads that I am porting for my 383. Now I keep reading that using a set of 2.00/1.56 valves would actually be better. I looked into a set of LT4 valves and they are stupid expensive. Will I be ok using the 2.02/1.60 combo or should I sell them and get the 2.00/1.56's? I really need some feedback on this..

 

Depends on how the port is setup. There are some guys going really fast on 2" valves. Proper port work and shape, the head can support higher velocity profiles you would see with a 383 thats revving up to make big power. Eventually tho, the valve size will become a restriction and a 2.02 with a port matched to that valve size will out power it. For 23 deg heads you can be velocity limited with air flow, and can only open up a stock casting so far before running out of room. Bigger valve may help here, but then again not always. The guys from advanced induction seem to have found a good port to compliment a 2.00" valve. But i have also seen 2.02-2.05 valves still make good power.

If you arent pushing power limits of design, then it really doesnt matter, use what you have bought already. Just configure the setup around that valve size. Those heads have small chambers and larger valves will only become more shrouded. Going much larger will need chamber opened up alittle to see benefits and drop compression alittle but not a bad thing with a 3.75" stroke.