I’ve hit the breaking point on header leaks. I’m tired of gasket after gasket failing, so I’m ready to spend more money than should be necessary to get the headers to seal.

Issue #1: Header Studs vs. Safety-Wired Bolts

I’ll be installing these headers (again) on aluminum heads, and I don’t like the idea of installing and reinstalling threaded steel fasteners into aluminum. Whatever fasteners I choose will be stainless steel from ARP.

Here are my options:

Hex Bolts 400-1101 $17.88
12 pt. Bolts 400-1201 $17.88
Hex Bolts (drilled for safety wire) 400-1103 $30.95
12 pt. Bolts (drilled for safety wire) 400-1203 $37.69
Hex Studs 400-1412 $47.95
12 pt. Studs 400-1402 $77.95

What is a better option? Use the studs without safety wiring them, or using the pre-drilled bolts and safety-wiring them all together? Ideally, I’d use the studs safety-wired together, but those nuts are too small to drill a hole through the side of one. I have enough extra room to deal with installing the headers over studs. I’ll use lock washers on both the studs or bolts this time.

Issue #2: Which Gaskets to Use?

I’ve read and it seems like the top 4 are (in no particular order):

Earl’s Pressure Master $40.39
Mr. Gasket Ultra-Seal $14.88
Percy’s Dead-soft Alum. $34.95
Fel-pro Steel-core Laminate $15.99

I haven’t used any of the aforementioned types before, other than the Mr. Gasket Ultra-Seal. But, I didn’t soak them in water as some have recommended before installation. I’ve also tried Permatex Copper silicone and it’s helped somewhat, but still hasn’t solved the problem. I’ve cut the header flanges in between the end cylinders and middle cylinders. I haven’t had the flange surfaced for flatness. Would it be worthwhile? I’d hate to grind away too much of the weld on the inside of the flange, so maybe I’d try to weld on the outside of the flange to reinforce it. The headers are the cheap Heddman variety, so the flanges aren’t very thick. Out of the above 4, what is the gasket of choice? Any other tips?

 

If you want to stop abusing the threads in the head, studs are the only way to go. I see no point in the 12 point though, just go hex.

As for gaskets, on LS1 the STOCK MLS (multi layer steel) are about as good as it gets. Similar style MLS gaskes are good on LT1s, but you may have to drill out the end holes as many are made for the SBC style D port heads.

I've always just used good steel header bolts, MLS gaskets, and retorqued after 1 or 2 heat cyles, then again after a week or two. After that, I just check them occasionally, and have no problems.

If you have cheap headers with a thin flange, it's likely the header flange is not flat... and I have no clue why you would cut the flanges. That'll just make it easier for the heat in the pipes to twist the flange.

Other tips: next time, or when you get tired of leaks, buy good headers with a nice thick flange, and check for flatness before install... and DON'T cut the flanges.