Seff

Looking at my newly valve job'd 7a heads, they seem to have a crossover between the two middle exhaust ports, which means my headers won't properly separate those two ports, if I'm looking at it correctly. Is there a special procedure to fill those crossovers out, or just weld in a piece of appropriate scrap metal? Will I kill the tensile strength of the head that way?

Thanks.

cutlassefi

Do a search, it's been covered a hundred times. You'll need to weld the center divider as well to get the maximum effect.

Seff

The reason a search yielded nothing is because what I called a crossover, was the center divider you mentioned. Thanks for the heads up.

So, as I asked, should I be wary of welding, or just go for it, at long as it's smooth when I'm done?

Seff

Ah, found the aforementioned info - so, blocking off the intake manifold heat crossover ruins cold-start performance for a carb'd car, but there's nothing to fear if I'm going for injection, right? Then all I have to worry about is whether the welding can damage my heads or not.

captjim

Actually, they are 2 different things. The seneter divider is on the exhaust of the head, the crossover on the intake side. The divider is welded up then smoothed flush, no biggie. The crossover is more complicated, melted aluminum (old pistons wok great) is poured into the crossover. Ideally, this is done before and port work so the chambers can be smoothed out.

EDIT: these can be filed and press fit into the heads. Not a perfect solution, but better then nothing,
http://www.summitracing.com/parts/edl-2733

Seff

Aha.

Problem is that I'm not ready to put my injection system on just yet. I'll have to think this over.

Mind you, I am running a '71 350 while my '72 357 is slowly being rebuilt for manual trans, high comp and injection.

RAMBOW

Performance heads all have the crossover blocked- its not a big deal. Takes a couple more mins to get the car to fully warm up. Get an electric choke and you'll never even notice.