Is there much to be gained bying going to a 2.02" valve from the original 2.00? I'm going bigger on exhaust side for sure, as I will be spraying.

Thanks for any and all input.

The heads are being ported out further and matched.

 

Not enough to justify replacing all the valve seats to accomodate the 2.02 valves. The stock valve seat itself is not big enough to do a good valve job using a 2.02 valve. If you want bigger valves and are willing to step up and replace the seats then at least jump to a 2.05 valve.

 

I'm no head expert, but I've always heard/read that for a max effort LT4 head you should setup to a 2.02. On an LT1 casting you probably don't need anything bigger than a 2.00. The best bang for the buck would be to keep your LT4 valves. I'd get with LE or Ai and see what they think.

 

Myself I'm sticking with the LT 4 sodium filled intake valves, they are so light. Also I fail to see how .020 on the diameter is going to make much difference?

 

2.00" valves - 3.14sq.in.
2.02" valves - 3.20sq.in

About a 2% increase in size. 2% increase in power would be like 6hp. Not really worth it unless you are rebuilding the heads anyway.

 

I going with 2.02 on lt1 castings so it can be done. I wouldnt go through all the trouble to go from 2.00 to 2.02

 

I'm going with 2.02 on lt1 castings too

 

I know of atleast 1 LT1 car on this board that's running 10.9X, N/A with ported LT1 castings with 2.00-1.57" valves...On a 355.
http://www.geocities.com/herrint/95Bird-1.html

Frank

 

i would not go to 2.02 valves because theres no more performace gain over 2.00 but you do have extra weight to move. if you want bigger evalves just get new seats put in and go to 2.05 on the intake and leave the stock seat and put 1.57 exhaust. that what i did and my flow numbers are about 8 cfm across the board more than the average lt1 ported head.

 

Putting a larger valve in the same size chamber can also hurt flow because it shrouds the valve...

Frank

 

The OD of the intake valve seat insert is 2.00" A decent valve job puts the OD of the 45* cut within .005-.010" of the edge of the valve OD. If you have a 2.02 valve that you want to drop in there then you certainly can but you will not be able to open up the valve job any more than using a 2.00" valve or your valve will be seated on aluminum which is not a good thing. Using a 2.00" valve and a good valve job will actually flow better in this case because there is less shrouding done by the valve.

 

I agree, unless you change the seat and unshroud the valve the valve area will be wasted.
But if the head is designed around bigger valves (AFRs) then the 2.02 will work nicely, we evenwent to a 2.08 valve on a freinds ARF heads (mine still have 2.02s but plan on going up) He gained about 6-8 cfm accross the board from .200 on up.