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So i just bought a set of 243 heads and i was wondering if i should run them as is or have them worked a little bit (ported,polished, shaved etc.). I'm running a 220/220 .551 112 cam and ls6 intake but i dont want the heads to flow too much... and won't these heads stock lower my c/r since they have a larger combustion chamber? I haven't really dealt much with heads and what not so any advice is much appreciated!
Yes they will drop your c.r. You'd have to shave .020-.030" off to get back to your stock c.r. if my numbers are correct. if your considering getting them ported I'd do it now, otherwise you'll regret it later. You can also look into a thinner head gasket to get some of that compression back
where did you happen to find the heads and how much did you get them for if you dont mind me asking. im on the search for a set myself.
on a 5.3, 243's will lower compression quite a bit. If you're staying N/A, i'd stick with worked 862's or some patriot heads
i got a set of 799's from this place http://www.jakesperformance.com/Home_Page.html for $500. I don't see any engine parts on their page anymore but it might be worth a call
If you're paying to get your 862s worked, why not just pay for work on some 243s and have them milled and a 3 angle job? You'd spend a couple hundred more but you'd have much better flowing heads. They put 243s on the NNBS for a reason... they're nice.Quote:
Originally Posted by oleshifty
Get a port and polish job done on the 243's. Mill them 0.030 and have your compression back. Put a set of LS7 lifters in and use 7.40 pushrods. Done deal...
Thx for that info bud!!! Thats my next step.Quote:
Originally Posted by DBRODS
When i was looking into 243's....even milling down the max, the compression was still going to be lower then my stock 862's. Was the only reason i got a set of those worked/milled down to raise compression above stock.
Lambo is running 862's and I THINK he's one of the fastest 5.3's. His guy is doing mine too. If the block was a 6.0, by all means, 243 will flow better. Sure most of you guys here know more then me, but few months ago I did tons of research and talked to a few machine shops, and they all agreed 243 would make me slower, and recommended working factory heads IF staying n/a. I went with a milder cam, so that could be part of the reason as well.
i bought them off yellowsierra02 for $450. well i sure dont wanna spend all my money on a set of heads thats gonna make me slower...
well from what i'v found approx. .0065" milled off the head will take off 1 cc. the 243 heads have a 64.45cc combustion chamber and the 862 heads have a 61.15cc combustion chamber. So after some math it looks like it would only take around .022'' of milling to get the 243 heads to the same compresssion ratio as the 862 heads ;)
Do all the newer 5.3s that have the 243s have flat tops or what's the deal there?
yes, the 5.3 HO have the 4.8 pistons. If my milled 862's don't do it for me, that will be the next upgrade :)
if i shaved the heads .030" will the intake bolt holes still line up??
Yes...
PS, my 5.3 is the LMG with 9.9 CR and 243s.
and the intake runners will still line up with the intake ports on the heads after shaving the heads?? sorry about all the questions i'm kinda new to this and i'm trying to get all the info i can before i start spending a lot of money
243 heads suck, they won't line up after being milled, and they loose power compared to 862's....
pretty sure that was directed at me. Guys with z28s/trans ams, like putting 862's on their engines to bump compression, 243s are good heads for certain applications, but not for everybody. (you're def one of those guys who knows alot more then me, just throwing out things I've heard/found in my research)Quote:
Originally Posted by DBRODS