Well, Don and I spent the day filling in the crossovers on the Pontiac heads. Now that we are done,
I have to say this is not for the faint of heart. Getting the temperature of the aluminum hot enough
to melt was a project in itself, but after turning up the acetylene pressure on the torch just about as
high as the regulator would go, the metal did finally puddle on down into the necessary liquid blob in
the cast iron pot.

There are also several sources for the aluminum. Some use old Quadrajet carburetors. I couldn't bear
to toss in a Pontiac carb, so I made the easy sacrifice of old Chevy pistons, but we had trouble getting
the pistons to melt, so we switched to an old screen door frame  that melted very easy. The door and
window framing is a high quality aluminum and produces very little slag.

A strange side effect of using the barbeque for pre-heating was that the heads were the most perfect
basted-turkey color. Only thing it could have been was the gassing of the left over grease on the grill.
Whatever it was, it wiped right off.

(Click on the thumbnails for a larger picture).



Previously I had made up the necessary block off plates and we had bolted them in place and placed
the heads into the barbeque. The preheating of the heads seems to be a debatable step, and
several people say that you can pour into room temperature heads. Better safe than sorry, and we
got the heads up to about 400 degrees in preparation for the molten aluminum which is probably
close to 1700 degrees.



The pour was actually the easiest part of the job, and we only had to fill one port and the aluminum
came right up to the same level on the adjoining port. Hindsight proved that we over filled by about
a 1/4 inch, and it did require some extra grinding. After letting the heads cool for several hours, we
removed the plate and found that the intake side of the plug was perfect and required no additional work.



The valve side of the project did require quite a bit of grinding, but at least there was enough material
to fully shape the new port design. Next time we will cut the pour off sooner.



Time on the project took several hours counting prep and cool down - While we don't have any dyno
comparison, I can say that the exhaust note is much sweeter with the exhaust ports isolated.  Just remember
that any choke that runs on crossover heat will not function properly, and the choke should be changed over
to electric.  The good news is the heat is reduced to half under the carburetor and the fuel/air density has to
 be tremendously improved with the fill.