I've been out of it for 8 years, whats the new heads to run on 408 or something similar. used to be 317s n/a

sounds like everyone is turbo now but ill probably keep n/a

seems like prices have come down on internals and headers etc from 8-10 years ago as well

 

Do you want to run a stock head or like a ported head from a vendor?

243/799 heads are hard to beat for how well they perform for a stock head and would bump the compression over a 317's.

Maybe even some square port heads from a GEN 4 motor could work if you want a factory head. Something off the 6.2's.

 

what ever is going to give more flow /power

 

different intake with square ports?

 

As stated, you can’t go wrong with some stock, or worked, 799/243 heads. Also, 821/823 rectangular port “LS3” heads move some serious air straight from the factory!

 

My 408 hasnt been started yet, but....

Its the TSP/Wiseco rotating assembly. I think I paid $2800 for it? I'll have to pull the specs, but maybe the price will help you find it if you look on their site.

Its a 10.5:1 build, intended for 16psi on E, 12ish on 91.

Long story short, its got stock LS3 heads with +1mm oversized intake valves.

 

Another good thing about the L96 engine 823 heads, is that it comes factory with inconel exhaust valves! I’m not sure on the intake valve, but they’re either stainless or inconel as well.

 

LY6 also has inconel exhaust and 823s

Intakes are solid SS. I actually have a set FS if anyone needs stock stainless LS3 size pull outs

 

nice! I knew it was something along those lines. Pretty impressive GM used these materials on stock valves!

 

317 were cheap and aftermarket heads were expensive in comparison. However most 408's never performed that well on the top end cause they couldn't breath.

With a 408 you need to feed that beast. I would step up to an aftermarket head. They will flow more than any ported set of factory castings.

A good exhaust system will help too.

To Quote the late John lingenfelter
"The worlds's best cam combined with a poor set of heads will produce an engine that's a dog. But bolt on a set of great heads even with a poor cam and that engine will still make great power."