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OK, enough mechanical rubbernecking! How do we get the new head gasket to seal using only the tools on hand? Surfacing the cylinder head with a file sounds like a terrible idea until you exhaust all other possibilities. Once you realize there are no better options, you just focus on the quality of your filing work.
The trick is to keep the file as clean as possible so you don't accidentally gouge the surface when you drag some trapped file debris across the head. I used a wire brush to clean the file (brush along the grooves of the file) after every single stroke. Also, it should go without saying that you only work in the file's cutting direction.
Once the high points were knocked down, I wire brushed the pitted areas while hosing them down with brake cleaner. With the surface thoroughly prepped, I then mixed up a batch of JB Weld and smeared a thin coat across the head, using a razor blade as a squeegee. JB weld is supposed to be good to about 350 degrees, which means the stuff in the combustion chamber will burn off, but the stuff under the head gasket's fire ring should actually survive.
Maybe.
Got any better ideas?
Luckily, we had the forethought to rent one of Buttonwillow's luxurious pit garages, which meant we had light, a workbench, and electricity. We set two space heaters up to accelerate the curing of the JB Weld while we ate dinner.
After a few hours of accelerated curing, the file and wire brush came back out. After about half an hour of methodical file work the gasket surface actually looked like it might seal for 8 more hours of racing.
As a last bit of ghetto insurance, we applied liberal amounts of copper gasket spray goo to the gasket, cylinder head and block. I've never used this stuff before, but it didn't seem like it could hurt.
Dropping the first head gasket into place, the bolt landed too softly. We quickly realized the head bolt holes were full of fluid, which probably drained in while the head was being lifted off a few hours earlier. If we tightened the bolts, the oil and/or water would get forced up past the threads and contaminate the head gasket surface. Something had to be done. We quickly borrowed a shop vac, duct taped a hose to the nozzle, and used that to suck the bolt holes dry.
Since we had no idea if this JB Weld fix would work, we did what we could to lower the stresses on the new gasket. Wiring the wastegate wide open really should have killed power output and lowered cylinder pressures, but it really didn't hurt that much. Boost response was worse, and peak torque (and thus peak cylinder pressures) were clearly down, but peak power was unchanged and the car was actually faster, thanks to a fresh set of tires. At high rpm, our wastegate is normally wide open, so opening it earlier just slows boost response.
