LM7 383 Build Up

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Originally Posted by pl4yboy

243s for NA.

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aren't the 243 heads off an ls1?

They were also on LS2 engines.

I have some 241, 862, and 706 heads available for a decent price. Would the 241 LS1 heads be more desirable than the 706 and 862 5.3 truck heads?

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Originally Posted by RedHeartbeat

They were also on LS2 engines.

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Also on the newer GMT900 5.3s.

The 241s would be your next best option if I remember correctly, but I would think you could find some 243s cheap enough nowadays to make it worthwhile. The 241s don't flow as good as the 243s, but make around the same compression I think. With a good port job, your 241s could flow decently well though. After all, they were used some sweet F-bodies.


Here's a link with a little info, not much.
241 heads vs 243 heads - Page 3 - LS1TECH

So if i decided to go with the 243 heads or perhaps the 241 heads, would i need a different intake manifold and/or any other parts? or can i use all my stock 5.3 stuff?

Stock 5.3 intake would work.

So it appears that there are two different types of 243 heads, the ls2 heads and the ls6 heads. Is it really worth it for this build to get the ls6 heads over the ls2 heads?

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Originally Posted by blackout

So it appears that there are two different types of 243 heads, the ls2 heads and the ls6 heads. Is it really worth it for this build to get the ls6 heads over the ls2 heads?

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They flow the same, just different springs IIRC.

243 heads have two different setups, one setup from the corvette LS6 will have sodium filled exhaust valves and the 243 heads from all other vehicles have the old standard plain valves.

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Originally Posted by RedHeartbeat

243 heads have two different setups, one setup from the corvette LS6 will have sodium filled exhaust valves and the 243 heads from all other vehicles have the old standard plain valves.

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Thats what it was, the valves.