Cometic or ????

BARRACUDA1968

Well-Known Member
I was tempted to try Cometics again after talking with a couple known engine builders but with my sh$tty luck I decided to use felpro's because I knew they would seal. If my tunes right I shouldn't need to worry but having a little room for error would be nice. I probably won't or need to run over 23 psi anyway to run my number.
 

TurboWh1

Active Member
I hope to have my heads back soon, so I will need to pick out a gasket. The Felpro's seem close to the old original gaskets from what I see online. Do they handle the high boost? I will probably be pushing my car a little harder once I get it all back together.
 

BARRACUDA1968

Well-Known Member
Nick Micale runs them in his race car and I have talked with others who have had no issues with them at higher boost levels. Just make sure your tunes good.
 

turbo nasty

Turbo Dojo / MNTR
The problem with factory style HG's is when they blow they blow the graphite fiber crap all in the engine and I dont give 11 craps about whos running or ran what number with them. I for one dont like the "Fuse" theory when beating the F#$K/running elevated psi out these engines. As one lil issue can pop the factory style gaskets where a cometic or similar style could handle it and rock on. Now, this doesn't mean banging off the factory ecm fuel cut at 25 psi halfway down the track or some darwinism crap like that. Example.....lets say the fuel psi reg line blew or map sensor line failed feeding the map to turn on the alky and you went WOT and as the boost came up you saw KR on your knock gauge or SM and quickly lifted. I've seen the factory HG's pop in this exact scenario and then its tear down and redo. Cometic or similar will take this and rock on. Now granted both scenarios aren't the best for lets say...rod bearings....but now with factory gaskets you have all that crap blown into the valley and the water or coolant in the oil and ALL the bearings saw their life flash before their eyes and or they are dead as well as your crank and rod journals. IMO its a stance and mind set as far as headgaskets go....some think fuse and others think thats a weak headgasket. If it blows and puts the crud and coolant or water through the engine what are you saving...maybe the crank and block and maybe not. Ive torn down several 109 engines that had the "Fuse" gaskets and they had used that "Fuse " a few times and have seen cracks from the mains to the cam bore, around mains broke main caps, etc. run the best and strongest headgaskets you can. There isnt headbolts at 12 and 6 o clock on our engines...think about it.
 

earlbrown

runs with scissors
So is the concencus, Cometic still my best option? I don't beat on my car too often and I'm usually conservative when I do.


No. Cometics are only an option if the block is machined flat, flat, FLAT and smooth smooth SMOOTH! If those two aren't DEAD NUTS thre should be no MLS gasket on that engine.

On my personal engine I got the feed and load on the surfacing machines at the 'sweet spot' then took a diamond stone and went over it with cutting oil. That was done on the deck and the heads. Then I filleted open the Cometics and copper coated the hell out of all 6 surfaces. For me, that method works 100% against all three potential leaks. It works so well that my current 9:1 4.2L has one gasket that's been reused twice and one gasket that's been reused three times.
That being said the only reason I have Cometics is I wanted the custom .027" gaskets to get my quench clearance where I wanted it. If I had made my 'custom' shelf forged pistons first I would have just moved the compression height and stayed with stock style gasekts.

If your heads and deck aren't machined 'perfectly' (and I don't mean belt sanded or poor finish that you can feel with a fingernail) stick to a composite head gasket.
 
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