highschoololds

Can someone explain to me the process of filling the exhaust crossovers? I understand that the process of welding the divider means to bring it up to gasket surface level. Can this be accomplished with a MIG?

Thanks for the info.

RAMBOW

It involves melting aluminum or zinc alloy and pouring it into the exhaust exhaust crossover port, usually from the exhaust manifold side of the head.

Once the aluminum or zinc has cooled & hardened, you then shape & blend the material in the two center exhaust bowls.

There are a bunch of posts and some pics on the Real Olds Power site if you search for them.

I'm getting ready to do this on my heads, but haven't gotten around to borrowing a oxy/acetalene torch setup from my father-in-law yet. I'm going to melt down a couple junk pistons, but aluminum melts at 1200 degrees, so you need a full on torch setup w/ rosebud tip to get it hot enough to melt.

Many Speedshops sell a special zinc alloy for this exact purpose that has a little lower melting point (~800degrees) which would make the melting process a little easier.
a chunk of that stuff runs about $40 + shipping. Junk pistons are usually free if you ask a machineshop or another gearhead friend that builds motors, thats why i'm using them.

i have a bunch of links to threads & articles about doing it saved on my work computer, i'll post em tomorrow.

A lot of people will tell you that you can just take a peice of sheetmetal and cover the opening on the intake side of the head, and that MAY help by reducing the heat going under the carb, but you still have two exhaust ports on each side directly open to each other, which has no choice but to cause flow issues when with those valves fighting each other.

By filling the crossover completely, not only do you eliminate the hot exhaust gas going under the carb, but you also properly separate those center exhaust ports, solving any issies of the two exhaust valves sharing the passage.

SBORule

I wouldn't do it, it will eventually come loose and rattle around in the head.

I have read people using a mig to weld up the divider to make it flush.

SBORule

edit

Indy_68_S

But then you'd lose that Olds burble, right ?....

RAMBOW

I don't know. I'd assume it would sound the same as anyone running edelbrock heads.

Qwik71442

Here's a set of C's I just did with melted piston. I'll be blending the bowls soon....

highschoololds

Thanks for the pictures! Helps a lot. Is the whole port filled or just the entrances? Could you elaborate on the bowl blending technique as well. Thanks for all the help.

Qwik71442

I completely filled the crossovers and as far as blending the bowls you basically want to massage (grind) the filled bowls to match the others. I can post or send pictures of this process as I do them....

Glad to help....