Here lately in non /6 application fel pro has disappointed me and ended up with having a few redo's which were done with Victor reinz gaskets and I gotta say the victor gaskets looked better out of the package and actually got better than the old standby, fel pro. I'm noticing fel pro has changed the material they use for some of their gaskets and not for the better.
First is the intake plenum gasket on a 360 mag in a Durango. Even though I went with the "cure all" 1/4" aluminum plate in place of the stamped sheet metal one that was OE, I still had an oil burner. The fel pro was too hard, (and THIN) I'm thinking shim steel or aluminum as a gasket would have even done a better job. I bought the reinz and soon as I unwrapped it and saw the difference in material I knew it was better. Went from a quart in 1200 to using no oil in the 4000 miles between changes.

Then on a neighbor's Ford (yeah I know) I struggled getting the fel pro lip seals over the cam phaser solenoids when replacing a valve cover gasket, I gooped it up with rtv to get the guy by for the time, when I went to redo the job I bought another fel pro. Struggle city again. Went back to the parts store and asked if they had just the seals without the while valve cover set// ane they handed me 2, victor seals. Guess what. Those went right in, no struggle, and so far 4 months later no goop needed and no leaks. There have been others but those are my 2 most recent. I've also had trouble with the material that fel pro has gone to on timing chain covers. Definitely sharp edges and easy to cut yourself on but no good for sealing leaks.
"They ain't what they used to be".

And this next one isn't just a fel pro deal, but when I built my last /6 I went thru several head gaskets before I found one that would work. My engine is only 0.020 over stock, and the problem wasn't the block but the combustion chamber, I tried a fel pro, a Detroit gasket, a victor, and I think the other one was a McCord head gasket. Every one hung over the combustion chamber edges when laid loose on the head, which was laying on the bench. This head had been shaved 0.030, chamber volume went from 60cc to 50/ and the fire rings still hung over. I VERY SLIGHTLY cleaned up a couple of rough edges on 2 of the chamber edges and that aggravated the problem. I'm talking very lightly rolling over a burr. Just in one spot on each one. Not all the way around the circumference, maybe a spot 10* wide , of the 360* "all the way around" would have been. The ONLY head gasket I could find that didn't overhang the chamber edges was the Aussie one.

In the world of import cars felpro is pretty much junk. The slimy blue valve cover gaskets will swell after being on the car for a few months. So if you have to pull the cover you either run the risk of leakage or a gasket that you have to wiggle/jiggle squish into place.

My own daily driver (01 honda) had its valve cover gasket replaced about 3 months before I got it. I got it with a burnt exhaust valve so I replaced the swollen "new" blue felpro with a factory gasket. 5 years later I expect that factory gasket will come off and be reusable.

Hmm. I just ordered 2 closeout Felpro head gaskets from rockauto and they look the same as they always did. The Mahle gaskets look good too, so probably either is fine. I have had the fire ring overhang the combustion chamber on 10:1 motors making 200-250 HP and not had trouble. I think it is really hard to blow a Slant 6 head gasket unless something is REALLY wrong with the engine/tuneup, or you are boosting/spraying it.

Helpful tip: I always overtorque my head bolts to at least 80-85 ft-lbs. Sometimes 90-100. Never had trouble. I always use a beam torque wrench not the click ones, which can be way off.

Only one I ever blew (out of maybe 40 installed Slant gaskets) was a good aussie ACL gasket, but it was 95+ deg out, 9 psi of boost, no intercooler or water injection, and on my early tuneups. Still drove it 130 mi home on 4 cylinders...

Lou

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Home of Slant6-powered fun machines since 1988

I didn't want to chance it having the fire ring exposed to the "action" within the cylinder... Even at only a verified, measured 8-1/2:1
And to clarify I never bolted it up with any of those other head gaskets until I got the Aussie one. So no, I didn't blow any of them. Still have all of them, unused, up in the attic.

I do wish that fel pro would bring back the valve cover gaskets as they were back in the late 70s-early 80s, the rubbery ones.