Who reuses their Cometic head gaskets?

[67Charger]

I remember this being a big selling point about being reusable. I Had to pull a head to figure out why a leakdown test on #5 with the piston at TDC pushed coolant out of the radiator. Looks like it was coming in right where the little embossment is before passing between the cylinders. I'm going to deck both heads, pressure check them, and reinstall.

Now, I can't imagine reusing the head gaskets. Who here does?

...also realized I need a vapor separator on my PCV system. Oil everywhere...

 

[moper]

Not sure which heads you have, but most heads do not come from the factory with a smooth enough surface for Cometics. So some leak when new but seal after some heat cycling and retorquing. Some guys use spray sealant (copper spray) on them. Some seal just fine as is and dry.
The block and heads have to be very smooth: 50Ra or better. Edelbrocks are on the line out of the box (50-60Ra), and should be touched up by a modern cutter to get the right finish if you want to ensure they're "right". Also to ensure they're actually flat... I've not seen any factory machined block, or a block milled by anything but a modern cutter (not the usual oldschool milling equipment but a machining center) that leaves the correct surface. Those can leave anywhere from 60-100Ra. The higher the Roughness average number, the rougher the finish.
I'd have your heads cut flat on modern equipment, and if the block is not that smooth, degrease them and spray a light coat of coppercoat on them. I'd also retorque after the first heat cycle.

 

[gtxracer]

I reuse Cometic gaskets on my engine. All the prep you mention has been done, add a little Copper Cost spray and on they go.
Bob

 

[WileE]

I've always copper coated head gaskets, and never reused any. Just don't want to take a chance with my (No) luck.

 

[67Charger]

It was Cometics that were leaking. I bought the heads new, ran them with standard FelPros, pulled the heads for porting, and reinstalled with new Cometics. Now, 5 years and 3000 hard miles later, I have tracked my coolant loss issue to that bad spot on the head. The heads still have the edelbrock deck finish on them. Maybe that was not good enough. The engine got really hot once in 2016, 250°+ while stuck in traffic with nowhere to pull over. That may have caused the initial failure. I've been chasing the slow loss since about that time. It will never run out, just lose about a gallon then maintain. I'm debating getting new Cometics, reusing these with some spray, or looking for a new option. I'm 4.36 bore, chambers matched to the 4.410 gasket, and cannot be less than .045 since I have closed chambers and am .007 positive deck.

 

[threewood]

The only reason I have Cometics is because they offer a .030" thick gasket to give me .040" quench. Otherwise I would have stuck with Felpro. No issues with the Cometics yet but I havent pulled the heads off.

 

[Glenwood]

I had my new alum heads installed on a fairly (run for 3 months) fresh block and torqued with .028 cometics. Didn't run the new heads yet and pulled them to work on the pushrod clearances. The gaskets left a little trace of coating and a fine imprint of the fire ring. I wiped the surfaces down with lacquer thinner and reinstalled without sealant. So far no problems.

 

[451Mopar]

I reused my MLS head gaskets once. Used the spray can copper coat on them and did not have any problems, but I also did not have alot of miles on that configuration, maybe 500 miles. I pulled the heads and replaced with CNC ported heads and I replaced the gaskets at that time.

 

[moper]

It was Cometics that were leaking. I bought the heads new, ran them with standard FelPros, pulled the heads for porting, and reinstalled with new Cometics. Now, 5 years and 3000 hard miles later, I have tracked my coolant loss issue to that bad spot on the head. The heads still have the edelbrock deck finish on them. Maybe that was not good enough. The engine got really hot once in 2016, 250°+ while stuck in traffic with nowhere to pull over. That may have caused the initial failure. I've been chasing the slow loss since about that time. It will never run out, just lose about a gallon then maintain. I'm debating getting new Cometics, reusing these with some spray, or looking for a new option. I'm 4.36 bore, chambers matched to the 4.410 gasket, and cannot be less than .045 since I have closed chambers and am .007 positive deck.

Yeah... Like I said some are fine. Some seap, then seal. Some are sealed, then seap...lol. I stay clear of the MLS just because of cost and I manage the distances during initial machining. I set quench distance by deck height during block machining, and compression ratio by chamber size during the valve job and corrections.

 

[67Charger]

I only used them because after losing a crank and going stroker as a replacement, this is just what the only combo that gave me the compression I wanted came out to be. I was zero decked prior and the new setup came out positive .007. New .045's and +.007 gives me a nice .038 quench. I'm going to go ahead and replace them because they have already leaked. I can blame it on the overheating, and I'll just start over with a fresh cut on the heads and fresh set.

 

[dvw]

I reused mine 3 times before replacing them. 15-1 compression.However I never had a leak. How does the gasket appear at the leak point?
I'd be hesitant to reuse a gasket that was leaking.
Doug

 

[67Charger]

The gaskets look fine, save a few spots where the black coating stuck to the head or block. I'll still replace them because they DID leak, whether or not it was their fault.