Should I go with stock valves or i assume bigger ones like 2.0/1.5? I'm going for 255/180 flow numbers. Also what brand valves? Vortec, Ferrea, Manley, something else?

When I take the heads to me machined and milled do i just say i want them to be at stock compression or do i need to tell them a specific mill amount? I believe they were milled once but not 100% sure.

Here are pics of the chambers if it helps any: chamber1.jpg chamber2.jpg

How about these

 

From personal experience using back to back tests on the same day, same flow bench, etc. On the intake side Manley RaceFlo 2.00" valves outflowed my stock valves throughout practically the whole lift range, and peaked approximately 3 cfm more than stock valves. I think the intake side flowed 245 cfm.

The exhaust side is a different story. The stock valves outflowed the Manley 1.55" RaceFlo throughout the whole range. I think with how my chambers are setup the bigger exhaust valve was shrouding a little bit. Peak exhaust flow was 179 cfm.

These tests were done on an admittedly stingy bench (so says the owner).

 

I did some research and I'm reading that bigger valves only help with 383s, big cams and such. I'm running the hotcam with 1.6rr so it wouldn't help me?

 

Honestly, it depends on your port work, chamber shape, etc.

Whether it's on a 355 or a 383 flow is flow, so I don't think you can accurately say that bigger valves only help on a 383.

Really the best thing to do is see if the machine shop you are going to has some extra valves laying around you can play around with and test back to back.

 

Bigger valves will help anything. I was thinking of this same thing. What's the biggest valves you can put in a LT1 head? I thought it was 2.05/1.60. I was thinking of going with 2.08/1.65 or something. Also what's a good price you have bigger valves put in and flowed?

 

^^