what set of heads are best for 1973...

[Panies]

...Firebird 400? looking to reach 500 Hp, without internal rebuild...
Edit: okay, guys. i know it's not that difficult or dangerous to get 500 hp out of this engine with a stock bottom end. the only fear of mine is that it's old.
i don't want to raise the compression past 10:1 and that may be a bit to high for me.

 

[InjunRAIV]

That's a lot of power for a stocker - why would you not build the whole engine up? Anyway, to answer your question: The 'best' heads would be the HO/RAIV heads (670?). They flow better than the regular high compression heads (10.75-1), which would be your second choice. You could also go aftermarket.

I would suggest a trip to your local news stand and pick up either High Performance Pontiac or Pontiac Enthusiast magazine (or both) and peruse the ads for high performance equipment suppliers. Call them up and listen to their advice.

 

[Mad Jack]

Butler makes the best products for the Pontiac Engine

But I would be cautious about going over 400 horse power on any engine without forged pistons, crank, and rods.

You can make 500 horse power without the forged parts on the bottom, but the engine won't last very long.

Don't expect these to be cheap. You can very easily spend over $3000 on a good set of heads. But you also need these to make the serious horse power you want.

 

[loaslostnfound]

500 hp power without rebuilding um okay but i must warn you
this will put your whole bottum end under extreme danger of a falt resulting in the loss of your engine but if i were you and don't care about that stick on some 202 59cc chambered heads and let her rip
but don't start till at the strip cause it is going to blow your adding enought compertion to take the bottum end to china
so tear it turbo!!!