Topic: Why did it break
We did a Lemons grade rebuild on the 302 in our Fairmont wagon. Rings, bearings, oil pump, gaskets. Had the heads mag'd. We tested it at MSR Cresson doing 30 minute sessions and didn't have a problem. We did one hour of practice before the Houston race and blew a headgasket at the #8 cylinder. We fixed it that night, but couldn't figure out why it let go. Started the race and 45 minutes in got the same symptom and assumed it blew in the same spot due to a warped head (one had been hot and I failed to have the decks checked). Pulled it apart back at the shop and found three cylinders on the other deck leaking to water.
Warped heads? Had them surfaced and it only took .0005 to get them flat. That wasn't it. Bad deck? I fogged it with paint and carefully ran a flat file across it. No low or high spots. That wasn't it. Bad torque wrench? Put it on a calibration machine and it's 1 lb off at 65 lbs/ft. That wasn't it. The car has an F350 dually radiator. It only gets up to 180* on track. It didn't get hot.
We did find, by accident, a crushed fuel line under the car. It did have a high mile per hour, high rpm (5500 - 5800) fuel cut out issue, but it was inconsistent. I'm wondering if the fuel supply issue caused it to go lean and burn out the fire ring out in the head gasket.
We've been throwing a lot of shit at the wall hoping some of it sticks. It has performance, as opposed to OE replacement, head gaskets. It now has head studs. I've re-torqued the heads once and I plan to do it more. We've got a friend with a chassis dyno and will put it on the rollers with a wide band. It's got an 1850 series Holley with the metering plate in the rear. Apparently it's metered like a #64 jet. I did up the jets in the primary to 74s long ago. I haven't heard any detonation, but it's loud as hell in there.
I'm really tired of swapping / fixing motors at the track. We're at something like 6 motors in four races. We're doing the 24 in New Orleans in a month or so. I don't want to spend it fixing the car.
So, why did it break?
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