I recently ordered a set of custom Cometic MLS head gaskets to get my quench down to .040". When ordering them I discussed the required bore size with their tech and he said a 4.165" gasket bore would be fine with my 4.155" cylinder bore as long as the combustion chamber did not extend past the bore.
It didn't so I went ahead and ordered them.

I got them today, and on the first page of the catalog there is a warning concerning overhang into the cylinder OR the chamfer. The tech did not mention this at all, and I will admit I "should" of known.

The problem is the gasket is a near perfect fit for the cylinders, but the chamfer at the top of the bore is not perfect. The bottom, and sides are almost exactly the same size as the gasket, but there is a SLIGHT overhang above the chamfer at the top of the bore. The gasket does not protrude into the cylinder bore, but is slightly larger than the chamfer.

According to Cometic this will cause a hot-spot, and detonation. :'(

Will I be ok? The overhang isn't more than a few thousands into the chamfer at the top of the bore.

The bad news is this is a custom gasket and there are NO returns.
At $160 they make a rather poor wall hanging, and should I need to replace them, that's $320 into head gaskets... :nonod:

Think I will be ok?

Thanks! :cheers:

 

If you get a really nice frame, they should look OK.

I can't comment on the likelyhood of success, but you really don't have much of a choice. The money is gone. *I* would be inclined to try them. That way there is a chance you won't have to spend an additional $160.00. If they don't work, you'll have to replace them. *I* have never tryed or done this, so my thoughts are more philosophical, than technical. Hopefully, others with actual experience with this will speak up. Good luck, and...

RACE ON!!!

 

CFI-EFI I called Cometic this morning and explained the situation. The tech told me I can remove the rivets that hold the layers together and use a small grinder to open the bore up so it doesn't hang into the chamfer.
He said it wouldn't be an issue and to just clean them up with cool water.

:cheers: :party:


[Modified by VETDRMS, 7:19 PM 2/24/2004]

 

Soryy to hear of the problem.

What CC are your heads?

Mine were AFR-210/68 CC and there was no overlap.


[Modified by ld85, 6:18 AM 2/25/2004]

 

I'm glad you have a solution. It bothered me when you announced your decision to go with these expensive gaskets. Then when they were causing a problem...

All's well, that ends well. Good luck, and...

RACE ON!!!

 

Well......it got worse. Turns out I have overhang into the combustion chamber as well. Way to much of a hassle to take off that much material so I ordered a new set with 4.200" bore today.

I'm $340 into head gaskets now... :sad:

Live and Learn

I am selling this set (new in box) for $75 if anyone's interested.

:banghead: :banghead: :banghead:

 

I saw your post in the parts for sale section, before I got here. I said, "Oh No!" Do you need a bore of 4.200"? Nothing in between? I know these gaskets are "reusable", but for how long? How many times? Wouldn't you be money ahead, in the long run, to bite the bullet and get the block decked? Good luck, and...

RACE ON!!!

 

Believe me, i'm having the same feeling...OH NO! :lol:

Yes, I need a 4.200" bore and i SHOULD have ordered them in the first place.

These can be used "as long as they look good." Which in most cases is 3-4 times. I wasn't concerned with the cost benefit of reusing them at all, i wanted to get my quench down.

At $95 to deck the block, yes it would have been cheaper (same price after felpro gaskets). And the end result was that I had less gasket space and more bore space to support the ring pack (nitrous use).
However, because I ordered the wrong part it ended up costing me double.

I wanted to keep the piston's in the hole primarily so the rings would be further down and have more support from the cylinder wall for nitrous use.

I tried to eek the last few thousands out of it and I paid the price.

LESSON LEARNED!

Also, time was a huge consideration and It would take too long ot tear the shortblock down and have it decked, ect. I want to have this done by March 12th. Its going to be CLOSE.

On a positive note, I am really looking forward to racing this season, hopefully the tranny and rear end will hold up. :blueangel:

Thanks for your input, much appreciated.

Travis :cheers:

 

I probably shouldn't mention this because it's too late, but... The whole idea of running the ring pack down lower to protect them from the heat of forced induction, is to get them further from the top of the piston, further away from the heat of combustion. That calls for a piston with the ring grooves further from the crown of the piston. The piston deeper into the hole will accomplish, little or nothing. The ring placement dicision was made when the pistons were ordered. Sorry. Good luck, and...

RACE ON!!!

 

Travis sorry to hear about your misfortune. I may be able to use these gaskets. I'll call my builder and see what he says ;)

 

CFI-EFI I'm glad you mentioned that, and no its not "too late." I know an economical choice WOULD be to deck the block, but i'm not exactly after the economical choice, the time consideration is the most important at this point. You are right about the ring pack, my mistake. However because it cannot be changed there is no difference between a shorter deck and a thinner gasket, except time. I am presumably getting a "better" gasket at a higher price. The fact that I had to do it twice is just how it goes sometimes.

Thanks again for the help!

:cheers:

Smoked Tires I would like to find a useful home for them, let me know what he says. :cheers:

 

:sad: My engine is in the assembly room now & the 11.0:1 compression was calculated with .040 thick gaskets so I can't use yours, it'll put me to high for pump gas :sad: . That's a great deal for someone though.

 

Exactly, taking everything apart, decking the block, etc ,,, its an easy decsion,,,, $140 or tear the engine apart again with spring around corner?
Decision made, new gaskets :hurray:

My engine came out 4 time last year,, this year, I hope, ZERO!

 

SmokedTires No problem, i'm waiting on a couple replies from people who are interested. At 46% of retail i'm sure they will find a home.

ld85 I am hoping that the motor won't come out again until next winter. We will see... Also, the new set (larger bore) were $183 after shipping. :(

 

I feel your pain, like I said engine came out 4X last year...

Good thing is you are on your way to getting back on the road.

 

I wasn't suggesting you change pistons at this stage. I was simply commenting that the piston, down the hole, wasn't much of a consideration in the future use of nitrous.With all due respect, how much more is a "better" gasket worth, over a less expensive gasket that isn't likely to cause problem? My concern is as much over what it will cost for future gaskets, as it is for these, now. I think, what you are buying, here, is time, as much as anything else. I am NOT criticizing that approach, merely pointing it out. No matter what, I hope you meet your goals, both, in time, and in performance. Good luck, and...

RACE ON!!!

 

CFI-EFI Man, we just seem to be going round and round. :) I don't believe i've stated once that what you say is wrong. I didn't think you were suggesting changing the pistons either.

For my applications, this gasket is overkill...true. My intentions are as follows: get this combo running and run it hard for summer. I don't suspect I will even have this engine long enough to worry about the future cost of gaskets.

I will admit I have taken the LONG way to solutions in my many projects, and i'm not afraid to admit I am quite NEW to all this. So i'm sure mistakes will be made. I appreciate input that helps me avoid those mistakes.
This will be my first venture into automotive racing (excluding autocross), and i'm really looking forward to it. I'm after a learning experience, i'm sure i'll get it!

My next project I would like to do is a centrifual supercharged small block.
I don't expect to use this motor for more than 10,000 miles.
The research, building and testing is the fun part, driving it is the aftereffect.

:cheers:

Travis

 

Dont sweat it,,,,you learn from experience, and at least you can afford to rectify the problem,,,

I always say,, a good plan acted on,,, is better than an excellent plan, NEVER acted on...

If this head gasket issue is the only problem you have, consider your self blessed!

 

:cool: :cool: :cool:
I don't mean to go round and round. I'm just trying to help. I'm not being critical of a slip up, either. You won't catch THIS Kettle calling the pot, black.

I'm glad if your future plans are such that this won't perpetuate ongoing expenses. I might have said less, if I realized that. And I have no doubt you will. Have fun, and...

RACE ON!!! :thumbs: