98camaro28

iTrader: (21)

Ok so here is the deal: I found a local junkyard with around 40 or 45 LS/LQ engines (at least 20 are 5.3s), and for pretty cheap. I want to know what heads would be the best to replace my stock 98 heads when I put my MS3 in. I plan on getting several sets to "tinker" with since the prices are pretty good. What would be the best UNPORTED heads to look for? Can someone make a list of heads and cast numbers to look for in order of best flowing to worst? ANY help is appreciated! THANKS!

Nitroused383

iTrader: (10)

Look for casting number 243 or 799. They come on newer trucks 06+ I think, 05-06 gto, c5 z06, and C6 LS2 vettes.

BaddBird

iTrader: (6)

243s also came on the 5.3s (ls4) in the 04 and up grand prix gxp and the impala ss.

Benner

iTrader: (2)

Fixed

98camaro28

iTrader: (21)

Will do! Where on these heads can I find the casting number? And how much of a gain, if any, will I get over my stock 853s?

deadhorse66

iTrader: (2)

You can probably look for in the neighborhood of 15 horsepower over a stock LS1 casting. Look at the left bank, front top of the head just below the valve cover rail, and you will see a 3 or 4 digit code on any LS based engine. A little fyi, the 799s are probably more rare than even a 243 nowadays, as they only came on 5.3 L33 engines which is the aluminum block Gen III high output. 243s are used on a LOT of newer (07-up) truck 5.3s. While they dont have the sodium filled/hollow stem valves, they have the same port design they've always had.

BaddBird

iTrader: (6)

Thanks for the correction.

98camaro28

iTrader: (21)

OK. So of those 2, which would be better? 799 or 243?

Nitroused383

iTrader: (10)

They are the same head just cast by 2 different foundries. The 243 supposedly has a smoother casting, but not by much.

Red99T/A

how much can one expect to pay for a set of these heads from a junk yard?