I'm looking into getting a set of stock 5.3 heads to clean the casting and polish the ports, and maybe do a valve job and mill a little. How much gains am I looking at?

If you do a proper competition valve job,you'll see a useful increase in performance.Whatever you do don't try to hog out the ports you can do more harm than good.

I was planning to just clean up the casting flag left (if there is any) and polish the crap out of them. Then I got to thinking it would probably be a good idea to do a valve job also, and maybe mill the down just a little. :drive:

If you do a proper competition valve job,you'll see a useful increase in performance.Whatever you do don't try to hog out the ports you can do more harm than good.

:werd:

I did a 5 angle valve job on mine, larger intake 2.00, unshrouding and .050 off thats it and of course 918's and ferrea 6000 series valves. Along with the cam this thing freakin screams the stock heads flow alot better than you think, if I were to get a port job I would only go stage 1. Keeping the intake runners tight and just removing material from the bowl helps keep velocity up which is what creates torque. To give you an idea I ran the numbers in my sig NA 5.3 in a 5400 lb z71
thats why chevy small block is king!!

I wasn't going to port at all. Just clean up any casting left, and polish real good. I guess a valve job would be a good idea too.

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.

If you do a proper competition valve job,you'll see a useful increase in performance...

What does a competition valve job involve? 5-angle grind and bigger valves? Anything else? Thanks!

I have heard that is better to go with a 3 angle job for street apps when I get my heads from WCCH they will have a 3angle job cause thats what richard recommended. But of course this going to be on the 6L too not sure if that would change anything.

A good competition valve job needs to be performed by an experienced professional and would include undercutting and radiusing the valves along with a 5 angle seat and hand lapping.A really good competition valve job should be worth about 20 to 25hp

A good competition valve job needs to be performed by an experienced professional and would include undercutting and radiusing the valves along with a 5 angle seat and hand lapping.A really good competition valve job should be worth about 20 to 25hp

he is absolutely right I paid 800 for the work and materials I had done to my heads and its well worth it, thats why no other ext cab NA z71 are even close to my times. Just because someone you call says this or that doesnt mean its right they want to sell you a product

I have heard that is better to go with a 3 angle job for street apps...

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.

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.

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.

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 :drive:

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 :drive:

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

I Took Valves From A 5.7 And Machined Them To Fit In 5.3 Head And Started Doing Some Port Work And Then Stopped And Decided To Go Another Way.the Heads Are Milled 35th,with 3 Angle Vavle Job And 5.7 Valves.
I Also Unschrouded the valves

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


Dunno should I?

Dunno should I?

Depends on how much you want to get into it. The more you mill the higher octane gas you need. I took .050 off my heads and people thought I was crazy but I run 93 just fine it has taken some tuning though. I think you could mill more but would worry about p/v issues if you have a high lift cam. I figured my compression now is around 10.6:1 for every point you up the compression it adds around 20 hp. You dont want to go over 12:1 on a street engine 13:1 if really want to be on the edge.

If I were you I would take another .020 off.


devil thats about the exact thing I had done to my heads except 5 angle job. I still want some vids damnit :judge: :judge: