best header gaskets?

[Kevin - Blown 95 TA]

hmmm... that's a good idea. It's a little odd that it's the #3/5 that's leaking right along the top of the port.

I forgot to mention this about this idea of sanding the flanges -

When I got my SLPs the independent flanges were uneven and twisted up to 1/8" in some places, so I called SLP and got some lame excuse and was told that they shouldn't leak . I needed to make sure, cause I was going to send them to get coated. So I took them to work where we have 2 big belt sanders. Took 2 hours to do both headers. The stainless just plain dulls the abrasives real quick. I got them pretty flat, but I pity the fool trying to do this unless they got some extra tough abrasive belts made just for stainless or other tough metals. The ordinary stuff doesn't cut it. Sure would have been simpler if SLP had just let them cool off before pulling them off the welding jig, or at least inspected them before they went out. Sure, let NAPA do it just as long as they give you a flat rate up front! Only remaining problem is if the angle is changed how the headers bolt to the heads, then that can affect Y pipe fitment.

[fastTa]

Yeah, the stock manifolds aren't too kind to the sanding belts either. They can also of course use their mill to true up the flange side if they are that bad. Usually the stock manifolds aren't that bad unless they have gotten really wet while they were hot.

[Joe 1320]

I forgot to mention this about this idea of sanding the flanges -

When I got my SLPs the independent flanges were uneven and twisted up to 1/8" in some places, so I called SLP and got some lame excuse and was told that they shouldn't leak

Bingo. I laid a straight edge against the flanges and sure enough they were as you described when I got them. I don't know if it was 1/8 off, but it was enough for me to worry a little. The passenger side was pretty straight. The driver's side had the twist to the center ports. What a coincidence that's where mine started to leak. Oh well, I've put a decent amount of miles on the first set and they weren't exactly the right gaskets to begin with.

[Kevin - Blown 95 TA]

If I hadn't got them to flatten out by sanding, plan 'B' was to bolt them to a thick plate and heat them up with a rosebud then tighten them down & let them cool. As much of a PITA as they were, I am glad I have stainless coated headers and it's been 5 years that they've been on there with no problems except that the Jet Hot coating turned grey. One of the trick things I did was to use studs in the heads. I got the ARP stainless (expensive) header studs and had to shorten them 1/4" or so, cutting off most of the bolt starter nubs, but those headers stay tight . I never have to mess with it.

BTW, after my header/supercharger/plug wire/cat install my hands hurt so bad from the 18-20 cuts I had that I couldn't get to sleep that first night.

[Joe 1320]

after yet another leak partly due to losing a couple of stage 8 retaining clips, I am stepping up to what I should have used in the first place.

Percy's Seal-4-Good "dead soft" aluminum. Part #66031 For D-port LT-1's.

Not only is it the ultimate seal, but if I happen to lose another clip and a bolt backs out the gasket is not history. I did the install on the dreaded passenger side. The driver's side Felpro 1406 is still holding so for the moment, so I'll get to that later. For now, it's a rolling test bed. The Percy's gaskets are a stacked aluminum layer that is pretty thick. As the gasket gets crushed, it conforms to irregular surfaces and a leak proof seal is created. They are reuseable too. Good thing, at roughly $40 delivered, they better be. The key here is it's actually a time saving call. I seriously think that any installation that is in this kind of close quarters warrants a little extra insurance against having to do it more than once. If I had done it right the first time, when the clip and bolt backed out, I could have simply retorqued the bolt and put on another clip. Instead I spent the day doing it all over again instead of finishing another project.