460 Header Gasket

[kitcarbp]

Purplevenom,

Hard to say why #8 leaked, dyno tuning and the higher exhaust temps likely accelerated the failure, not sure how many hours on your rig but, max power will test your exhaust joint for sure, thats where oems test exhaust manifold joint designs, at max power for hundreds of hours. A good exhaust joint will outlast ( no leaks or bolt torque loss) the engine on a 400 hour durability test. #8 was gonna leak eventually, your dyno session made it happen sooner.

Brent,
I checked my header joint condition using feeler gauges without a gasket first to find the lows and highs of the flange/head face when cinched up to torque. Mine are far from perfect. Mine is a WCC. Each side had one port that had .035" gap, so that port was tightened last during header install and checked with a feeler gauge to confirm no-gap. Yes there is restriction, but I wont notice this on the street, mufflers are the low hanging fruit to pick up easy HPs you can notice. I really need to have new custom header flanges cut with a better alloy steel to better match my port dimensions and that distorts less during welding. Another question for JK Racing, he most likely makes his own flanges. It appears my header flanges were made for std 429 CJ ports or other and do not match the Jon Kaase SCJ head exactly. Another optimization project down the road.