2 Head Gaskets???
 

Has anyone tried doubling up on MKS headgaskets. Two of them would give me .080 thickness.
I'm trying to be able to change compression ratio with out doing the machine work all over again.

Re: 2 Head Gaskets???
 

Art, you can get Copper Head Gaskets in about any thickness you need, stacking gaskets, i wouldn't reccomend that! Sounds like you have a lot of compression!

Re: 2 Head Gaskets???
 

Art, ditto on what WJ said. .... I run a .085" Hussy copper gasket on my Super Gas BBC 522@ 15 to1 and have no problems...The Hussy people are great to deal with for custom applications too...... I've had the best results sealing the water passages with either Permetex Super 300, or the brush on type blue Hylomar sealant. ..... Tom

Re: 2 Head Gaskets???
 

Art, Try looking up Cometic head gaskets for the correct thickness or call them. If you have any questions call me at the shop next week (516) 599-7182. B&B Auto Machine.

Re: 2 Head Gaskets???
 

From the cometic website, www.cometic.com

Can I order a head gasket with a different thickness than you have in your catalog?
Yes. Call Cometic with the engine type or Cometic standard part number (search online or in our catalog) along with the thickness you would prefer and we will create your custom gasket. (800-752-9850 or 440-354-0777)


Can I order head gaskets with a different bore size than you have in your catalog?
Yes. Call Cometic with the engine type or Cometic standard part number (search online or in our catalog) along with the bore size you would prefer and we will create your custom gasket. (800-752-9850 or 440-354-0777)

Re: 2 Head Gaskets???
 

Ditto with SCE, I use a .093 custom made gaskets.......no troubles at all

Re: 2 Head Gaskets???
 

ok, I'll ask the obvious. Doesn't having .080 or more clearance kill your quench? Or is there other factors to make up for it? (like the afforementioned 15:1) Huge domes, hemi with no quench to speak of...or am I right but this is a band aid?
(and sorry, I don't mean to be belittling a huge dollar well prepared race engine or offend by calling it "band aid")

Re: 2 Head Gaskets???
 

How much compression do you want to lose?

What are the bore/stroke, dome cc's, chamber cc's you're working with?

Solid or hollow domes?

I would never run a naturally aspirated engine with that much piston to head, unless it were a flat head or Hemi as mentioned.

You can work a chamber shape and volume, lose some dome (best option), sink the valves or use a tulip style.....????

Help us out here with as much specific information as possible....

Re: 2 Head Gaskets???
 

Bore is 3.484, stroke is 3.976. 7.5 cc dome, flat of piston(not dome) 0.010 above deck Head cc's 49.5. Stock head gasket is 0.040.
Using the stock gasket I come up with about 13.5 to 1 compression. The piston was sent back to the manufacturer to cut the valve reliefs as much as possible and shave the dome.
With the stock gasket I'll only have 0.030 piston to head clearance. 0.60 piston to valve with the smaller of the cams that are available to me at this time
Using an .080 head gasket will lower my compressiom ratio by over a point, give me 0.70 piston to head (quench area) and allow me to use a couple of larger cams.
The next motor I build I'll have a piston made without these froblems. But for now I'm going with these.
Called Cometic today and ordered a gasket from them 0.74 thick. I'll yrt 2 gaskets after I get the the running and dialed in. For now It's one less thing to worry about.

Re: 2 Head Gaskets???
 

I see, it's a clearance issue more than compression.....

I get a difference of near 2 (1.9) points adding .040" on the gasket.

Gotta do what ya gotta do, watch your tune up on that one.

Good calculator tools here.... http://users.erols.com/srweiss/index.html#jcalc

Re: 2 Head Gaskets???
 

Dave the calculator I used ( http://www.slowgt.com/Calc.htm ) gave me a slightly different reading (about a full point lower). Now I'm not sure which one is right?
I was under the thought that my compression was 13.58 to 1 with the 0.40 head gasket,
and about 12.16 to 1 with the 0.80 gasket.
Can anyone take a look at which calculator is correct?

There are only a few cams for the motor I'm using I don't want to go way up on the compression to start off plus the larger cams might have piston to valve issues. The overhead cam is probably more forgiving than a pushrod motor Due to very little weight. But I want to shoot for at least 0.060 The larger cam is .492 at the valve. The smaller one I'm using is .453

Re: 2 Head Gaskets???
 

Art, I use the calculator Dave uses. ...I also use Challenger engine software. ... Both programs came out with similar numbers,altho higher than yours, using the specs you posted. . .....You didn't spec the gasket bore, but assuming it is 3.520"i.d., both programs indicate 14.25 to 1 compression with the .040" gasket,and 12.75to1 with an .080" gasket, if the 7.5cc dome volume is the net volume,including the valve reliefs ......Tom

Re: 2 Head Gaskets???
 

The 7.5 cc number is the total dome displacement counting valve releifs and the piston flat area being 0.10 out of the hole. I poured the cylinder with the piston .500 down the bore. Got the volume of the bore and stroke times .500 then subtracted the volume from what I had measured. That was my dome volume.
The head gasket is 3.490.
I guess I'll have to run the thick gasket. 14+ comp ratio will be way to much for the cams I'm running but I can play with overlap due to 2 cams.

Re: 2 Head Gaskets???
 

I think the Weiss calculators are pretty good, within a couple of tenths on the ratio.

You should be able to come up with a good number for the gasket, I didn't have the bore size on it, but catalog gaskets have the cc's calculated.

Don't forget to plug in the "-.010" for the piston out of the hole.

Re: 2 Head Gaskets???
 

I added piston out of the hole to the dome cc's. I brought the piston down 0.500 then poured the cylinder. And figured the volume of the dome and the 0.10 out of the hole.
I hope I did it right?
I think the calculator I was using seems faulty 3 others had figured higher in comp ratio. Than the one I used.
Oh well I guess I'll be running a little over 13 to 1. With the 0.074 gasket. That will have to do for now.

Re: 2 Head Gaskets???
 

Shouldn't have needed to do that on the Weiss calculator.....it will register the "out of the hole" for you by putting the "-" in the deck clearance position.