Long story short, the rear-most exhaust manifold bolt broke off in the driver's side cylinder head, resulting in a nasty exhaust leak. I need to pull the head to remove the broken piece, but figure I could just upgrade the heads instead.

What are some CHEAP options for upgrading my '01 5.3L heads. Preferably under $500 for the heads and intake(if needed). Needs to look relatively stock since I'm in CA, so probably no LS1 or LS6 intake. Milling the heads?

Thanks!

 

243 out of a junk yeard from the nnbs 5.3/4.8 motors
bigger valves bigger intake and exhaust and smaller chamber
i would do a port and polish theyll do great

 

^^^^^ agreed, i would be careful milling the heads too much.. but bumping the compression up would help alot with low end response..

 

milling too much?
mine are milled .040 and other have gone .055 with no issues
On a dished piston 5.3 99-06 its take .028 to get back to stock compression
243/799 have a bigger cc chamber which drops compression if not milled

 

I'm running 243's (799's are the same heads, different casting number) ... Bigger intake valves, same size exhaust valves. Milled .030 with a .040 thick gasket, bumped my compression from 9.5 to 9.9. The cometic gaskets, heads, and machine work may run you over your $500 limit though. Depending on what you can get the heads for.

 

Im refering to if he ever goes forced induction and plans to push the boost #'s.. if your staying NA then mill the mess out of them by all means.

 

Dumb question to add to this would milling them down using a stock replacement head gasket would you need shorter push rods

 

Get a spare a set of stock 4.8/5.3L heads. A Bowl blend and a basic rebuild will keep it under $500. it will also net you some nice gains and you can swap them out at your conveince to minimize the down time.

Under testing the 2.00 intake valves showed signs of shrouding on the stock 4.8/5.3L bore on a flow bench. Some guys say no big deal others claim a slight loss on the low end. I don't have enough data to prove or disprove it either way.

Richard @ WCCH uses I believe a 1.94 valve on the intake on his stage 1.5 heads for the 4.8/5.3L. That and a basic bowl blend averages 40 CFM from around .300 lift on up. From just off the seat to .300 opening of the valve, the flow numbers barely change but after that you see a steady average of 40 CFM gain...

 

Good advice ^^^^. Take what you got and and get a competition valve job, bowl blend, mill enough to get compression up to 10:5:1 and freshen heads, seals, springs etc. If you don't have or aren't going to soon put in an aftermarket cam then you can keep compression close to stock if you want , but it wouldn't hurt to bump it up some especially if you think you may do a cam later on.

 

If he was to go witht the stock 5.3 heads, What would be a good year engine to get the heads from to avoid castec's??