[boater bill]

I finally got around to doing the end exhaust stud drill and tap job and filled the exhaust cross overs with melted aluminum last weekend. The drilling and tapping went amazingly well and easy with the drill press. Making sure the exhaust flange was 90 degrees to the drill is key. I used the header flange to make the center mark for the drilling.
For filling the exhaust crossover, I melted some cast aluminum piston pieces in a cast iron spoon holder with a propane turbo torch from Harbor Freight. It took less than 5 minutes to melt enough aluminum to fill one head with one pour. That torch has a huge amount of BTU's when the turbo button is pulled. I scrapped the dross with a screwdriver and that also worked well. I made some dams for the exhaust port from 1/8" aluminum and held them in place with packed steel wool and poured from the intake side. The only problem I had was one dam wasn't tight enough to the head and let some molten aluminum pour out as I was pouring. So the fill didn't get all of the way to the intake flange, but above the Y-junction, which was the goal.

The grinding in the exhaust port was minimal with the dam and pouring from the intake side.
Thanks to all who have posted previously on how they did these modifications.

Now to take the heads to the machine shop for clean up and valve cuts.

[Mister Pontiac]

Excellent, Bill!

[steve25]

Nice pour job!
Since you have a grinder, go back in the exhaust bowl and grind off the lip on the short turn and then if you can get up onto the crown of the short turn to grind off the factory locating nub you can pick up 10 cfm of exh flow per port in a hours work.

[MescaBug]

Looks good!

I also modified a few sets of 7K3 for headers, with iron. Shape it with a Dremel, looks like nothing ever happened. One set has been used extensively for the last 3 years, no leaks, works like a charm.