I wonder why that is? I bought some 5.3L heads on e-bay that were milled .005 and given a 3-angle job. Don't have 'em on yet but I'm curious to see what they'll add along with a mild Lunati cam.

 

3 angle or 5 angle valve seat cuts aren't the issue as much as the narrowed seats and radiused valves and long term durability.Most truck owner don't want to freshen up the valve job on their heads after 40 to 50,000 miles.That's the downside of a true competition valve job.

 

My guy was able to use the stock seats for the slightly larger valves anymore and would have to gone with bigger seats I think the biggest difference was going with the 2.00 intake and 5 angle

 

You can install 2.0"intake valves in a seat designed for a 1.89"intake valve,but the smaller bore on a 5.3 will shroud the valves not allowing full flow.You can get better flow with the smaller bore with a smaller 1.89"Intake valve that has been radiused for higher flow on slightly narrowed seats.

 

I thought about this and had him do some unshrouding its worked out well, I wish I had some numbers to compare smaller valves no unshrouding to larger valves with unshrouding that would be the real test.

Do you know of anyone who has done any test of flow numbers concerning the two setups or is it just generally accepted. I setup these heads as a test and so far they are performing better than expected from the track times Im getting I just need to dyno now that I have tuned for all of it.

 

You would need to compare the flow with a stock sized 5.3 bore fixture,the 2.0"intake will definately out flow the 1.89" with the bigger 5.7 bore.

 

of course

 

I would definitly get a 3 angle valve job not matter what.

 

I think I'm just going to get these for now

Matt, my buddy still has them heads off of his 5.3. Blended valve guides, cleaned up casting and polished, 3-angle v-job, milled .020. Good for about 3 tenths.

I don't think I can get the machine work done for what I can buy these heads for, and they are the cheapest ones I've found, and I know who I'm getting them from.

Hopefully we will see what they can do soon

 

sounds good
are u going to mill anymore off the heads?