Cometic Head Gasket

[bobscuda67]

I'm thinking of using Cometic head gaskets to replace the leaking one in my
car this winter. Just wondering if the thickness is as accurate as they advertise.
I have a zero deck block with magnum heads. So I'm looking at the 4.080 bore and the .040 thickness, for a good quench. Just want to make sure they actually measure 040 thick.

 

[1970Duster]

Yes they do.

 

[70aarcuda]

usually cometic head gasket require a different finish to the heads to properly seal....

 

[64 SRT8 Dart]

usually cometic head gasket require a different finish to the heads to properly seal....

Wonder what type of finish as I was looking at these same gaskets for my 318??
The finish on my deck and heads is smooth as glass with no evidence of cutting from the machine as I've seen on some heads/blocks.

 

[bobscuda67]

According to Shady Dell's website, the smooth finish requirement is overrated.
They seal on most all decks and heads. My heads are very smooth, but my block deck has the cutter marks on it. I'm hoping it is smooth enough for the Cometics.

 

[Oldmanmopar]

I wouldn't listen to anything shady dell has to say. They built a motor for me in the past . The heads leaked so bad it was unbelievable. They told me that they always use moroso block seal.

Ryan is the shadiest guy I met. Here is a pic of what happened to the ne and only motor they did for me. He is and A$$ hole as far as I am concerned. This was all due to shady machine work and parts that were not mine. Needless to say they paid for what they did but it took over 1 1/2 years. But I never got all my parts back. I got tired of waiting.

If the motor would have stayed together I would have never known they switch my parts. I don't know where he gets the pics for his web site. when I went there and walked in his two car garage all he had was a Harbor frieght drill press with a mill plate attached set up on concrete blocks. What a joke that place was.

The CNC milling he had done at a garage in the boone docks that he took us to was a 1/8 inch off from side to side. They ruined three blocks on me trying to stand good for what they did. Two X blocks and a Resto.

He uses other shops to do his work. I wouldn't let him build a Outhouse. Your **** would bounce back and hit you in the ***.

 

[swinger340]

I wouldn't listen to anything shady dell has to say. They built a motor for me in the past . The heads leaked so bad it was unbelievable. They told me that they always use moroso block seal.

Ryan is the shadiest guy I met. Here is a pic of what happened to the ne and only motor they did for me. He is and A$$ hole as far as I am concerned. This was all due to shady machine work and parts that were not mine. Needless to say they paid for what they did but it took over 1 1/2 years. But I never got all my parts back. I got tired of waiting.

If the motor would have stayed together I would have never known they switch my parts. I don't know where he gets the pics for his web site. when I went there and walked in his two car garage all he had was a Harbor frieght drill press with a mill plate attached set up on concrete blocks. What a joke that place was.

The CNC milling he had done at a garage in the boone docks that he took us to was a 1/8 inch off from side to side. They ruined three blocks on me trying to stand good for what they did. Two X blocks and a Resto.

He uses other shops to do his work. I wouldn't let him build a Outhouse. Your **** would bounce back and hit you in the ***.

Buddy of mine is running a shady dell 408 in a street car. After a yr and 2 cams he had another shop redo the oiling mods, good thing, mains and rods had extensive wear as well. obviously mods were not working. I assemble my own engines and a buddy of mine does my machine work. Does that make me an engine builder? Lol!!!!! I rather do my own assembly. I have seen to many half passed jobs.

 

[Oldmanmopar]

The only reason I went to shady dell was. He had the guides for my batten heads no one else I knew had them at that time. After paying him over 1100 to put guides in I thought I would let him build the motor the heads were going on.

I bought everything new. Crank, Rods , pistons, Cam . Every piece. And delivered them to him. What he didn't know was I stamped my parts and took tracings and pics. A lot of my parts I bought were not in my motor. Major parts were the Crank, Pistons, and Cam, Lifters and norse rockersGone. He also switched my New CSR water pump for a used one.

He charged me to CNC fly cut my pistons. He did them with a nail file and a 1/2 inch drill through my fresh heads. Then he sanded the tops of the pistons to hide the marks. When I saw the short block he told me he told me the sanding was to help atomize the fuel. Rider Engines in Carlise Pa. was part of this scam. Beware of these A$$ holes too.

I wasted a lot of money through him on that motor . This is Shadey dells mpotor in the car . It made it exactly 10 feet before it left loose and that was in reverse. That is a complete aluminum W-2 Batten top end I lost. Sucks They made more torque on the bottom then the Indys on the dyno and the valves were hitting the pistons. Second pic is the motor in it now built by HTA machine.

Block and heads looked like a mirror and still had seep with Cometics. Mr. Gasket tri-metal gaskets Never seeped on my blower motor in my truck.

For a street motor on pump gas I would go with a good Felpro composite gasket. Less chance of seeping into the cylinders when sitting. That could be a disaster and take out a piston if hydraulically locked.

Just some friendly advise . I use metal gaskets with boost or high compression only. And if I do let it sit I tap the starter and baby it around to make sure it didn't seep in the cylinders.

 

[Mad Dart]

I have heard a lot of Horror stories about Shady Dell. He does have a loyal following but I am sure those followers have never been to his shop and order over the phone to have stuff shipped. That is so funny…Harbor Freight & Cinder Blocks… LOL to the maxx.

I have used Cometic gaskets with and without the smooth finish. Have never had them leak. On my last motor that is now in my Scamp "Heads had smooth finish", I sprayed them with copper coat before I installed them on both sides making sure the block and heads were clean as can be. I use head studs on everything I do.

 

[bobscuda67]

My engine doesn't really need the Cometics as it only has 9.6 compression.
I would use a composite gasket if they made one to fit my .030 over 340.
The gasket I took off was a composite and it measured 4.140 and was supposed to be .039 compressed but was .042. I shouldn't have to settle for one size fits all.

 

[70aarcuda]

My engine doesn't really need the Cometics as it only has 9.6 compression.
I would use a composite gasket if they made one to fit my .030 over 340.
The gasket I took off was a composite and it measured 4.140 and was supposed to be .039 compressed but was .042. I shouldn't have to settle for one size fits all.

Correct..and that is why cometics are 100 bucks each.....the 30 buck gaskets cover at least 3 engine sizes plus overbores...

 

[Oldmanmopar]

My son uses Cometic on his 4 cyl. turbo motors. He takes the rivets out and does the copper coat on all layers. He said they do that at the machine shop on certain motors. One of them is a SB Mopar and anything LQ cooled with less the 5 bolts per cylinder. He now works a HTA machine as a machinist and builder. And is learning a bunch of tricks.

They are doing another 340 for my other Duster. Pump gas street motor for a driver.

I went a little overboard on my orange Duster. I don't regret it. But its not really practical for the street . Sooner or later it will get me in trouble. When you pull up to a stop sign and its shaking around at 1500. It flash stalls a 5500. Its very hard not to launch it. Even harder not to shift second and third with 456's and bellow the Tires. It is like driving a over powered shifter cart out of control. Shifting At 8500 your not steering it you aim it with a death grip on the wheel. If I were to do it again it would be 4 spd. or a lenco.

I better stop before I need to go out and take it for a ride. There isn't nothing like a High revving SB stroked that can take constant abuse. I hope they have them in heaven.

 

[moper]

Personally I won't run Cometics unless I really need to for design considerations (like the 383 or 273 builds where the standard stuff gives away too much.
When they are used - the surface needs to be very smooth relative to "normal" stuff. You can use coppercoat, and it's a good idea to remove the rivets, but the surface per Cometic needs to be 50Ra or smoother. Edelbrock heads ship with around 55 which is why some guys have leaks and others dont. It takes a modern high-speed cutter to get really smooth surfaces. In comparison the typical felpros and composites can seal from 50-110Ra. If your shop doesn't have a profilometer then they don't really know what level they are getting anyway.
I'll add - if you are not getting the correct compressed thickness you should review your block and head prep, depth of bolt holes, dowel pins, condition of the fasteners, etc. If the gasket is hit with the right load in the right sequence it will squish to the correct thickness.

 

[DaveBonds]

Yep. Most boost guys I know that run 1-2mm metals are going 60-80Ra min.

Just get a good set of Fel-Pro gaskets and at least have the heads checked before putting them back on.

I had one seal and one leak until I cut mine. Heads get more heat than the block at the gasket.

Oldman... That car is a quick trip to the big house. Be mindful about which shoes you lace up, and if you're running regular or decaf in your mug, if you are stepping out in it. Lencos are your friend for 1/4 mile. I don't know that straight cuts belong anywhere on the street, though.

 

[fishy68]

Running Cometics on my 408 and dimensions were just as advertised. Block and heads were decked to 50RA and I didn't use any sealer on them. No leaks at all going on 3 yrs. and 5000 miles