98formulata

iTrader: (4)

I currently have a lq4 with 5.3 heads. Time for some new heads. I can get some 243s locally for pretty cheap. Which would save me about 900 dollars over ls3 heads. Should I just hold out for some ls3s?
What are the real gains from ls3s over stock 243s

03Sssnake

iTrader: (20)

I would do the 243s for a stock bore 6.0L, unless you are planning on a 408 etc down the road. You can spend a little at the machine shop to have them milled, valves lapped and perhaps open up intake and exhaust ports some.

KCS

iTrader: (20)

I'd go with 243's. In fact, I'm actually working on some 243's to go on my 6.2L.

98formulata

iTrader: (4)

What's the hp difference between the 2? 30 to 40?

gtotoocool1

iTrader: (6)

What are your HP goals?if your wanting a strong running street/strip car,i would go with the 243s all day long.if its an all out,high rpm drag race deal,then the LS3s become more attractive.

98formulata

iTrader: (4)

I drag race it mostly, but its driven to the track. I shift a 6k. No hp goals just et goals I want to go as fast as possible on stock bottom end, not looking to break any records just wanting it to be faster. It only runs 7.80s right now

allan808

iTrader: (3)

Ls3 heads! more room to grow later.

wildcamaro

iTrader: (15)

Lots of info on here stating if you only have a 6.0 you can actually shroud the valves with ls3 heads I forget the exact threads but there has been a lot of threads about it...either bore it with ls3s or port the 243s with regular 6.0...just my 2

transaman98

iTrader: (16)

I have heard good things about TEA ported 243's with turned down LS3 valves. Didn't chris1313 put up some quality #'s with them?

98formulata

iTrader: (4)

Next question. I have some 317s laying around, should I just throw those on or wait for the 243s?

mchicia1

iTrader: (5)

LS3 heads since you save big time on an awesome (ls3) intake manifold. That is the most attractive thing to me regarding ls3 top end swaps. 243s are great, but a fast is very expensive compared to a stock ls3 and not much better.

Mill them, get a .040" cometic, and get a cam with decent intake valve lift which will help with the shrouding.

Always2Slow

iTrader: (8)

You can make a really nice setup with what you already have instead of spending a bunch of money if you put some porting in those 5.3 heads and get a set of stock 2.0 valves out of another head. The 5.3 head will help aid in compression on the low compression LQ4.

yonerhottlt1

iTrader: (21)

Since when were LS3 heads $900 more expensive than 243's?! I bought some brand new in the box here for $675 shipped.

A.R. Shale Targa

iTrader: (2)

The runners(port shapes) on your 317's are identical to the 243's....so if you
are looking for cheap flow but don't want to lose much compression then
have a machine shop do a quality valvejob and perhaps a quick cartridge roll
cleanup in the bowl area. Mill them .040" and run some .040" thick Cometic
head gaskets which should get your compression close to where you're at
with the 5.3 heads (assuming you are using thicker GM headgaskets now)
Also if those 243's you're looking at came off a ZO6 then they'd have the light
weight hollow stem valves, which helps with valvtrain stability at higher rpms.