What head gasket for HC heads?

[Lexveen]

I installed a new HC head “Sherman style” with a new copper head gasket. I drove a few miles and it started leaking. Water and bubbles came out along the head bolt between cilinder 1 and 2. I re-tightend the head bolts to 55 lbs but without success.
I took the head off, looked at the gasket and the head and examined the surface.
It appeared that the gasket does not fit well. The gasket is much wider than the seperationwall between the cilinders. The folded edge of the gasket hangs over the combustion chamber and is not compressed. If you zoom in on the picture of the head, you can see the markings of the folded edge. The part of the gasket between the edged is hardly compressed, so leakage of gasses is obvious.
The edge of the seal around the small water hole next to the head bolt is not well made so it leaks coolant to the bolt hole. When I removed the Z-head that was on the engine before, I noticed rust on the same bolt. However it did not leak to the outside and no gasses too.

Additional I did some measurements. At the picture from top to bottom the Sherman head that I just removed, below that the original head and at the bottom the Z head.
The width of the dam between the cylinders is respectively 7.5mm, 10mm and 8mm. The gasket is just under 10mm at the same place. The copper gasket does fit the original head, but not both HC heads…

But what now? Where do I find a gasket that fits properly?

[ModelTWoods]

Lex, I am taking a guess, but by your description of "Sherman style", I suspect that you have a head made by Kevin Prus of Canfield, Ohio, USA. His heads are touted, universally, as of being of the highest quality, so I suspect it is either a gasket problem or a deck surface problem. Most owners in the USA, use copper head gaskets made in the USA, either NOS or new replacement manufactured, and you are one of the first that I have ever heard having a problem. If the gasket you are using is of unknown or questionable manufacture, especially if its a foreign made gasket, that may be your problem as the contours of your gasket don't even look like they would seal a stock Ford head. I would contact Kevin, if it is one of his heads at:kprus@zoominternet.net or phone 330-774-7130 and ask him what brand of gasket that he recommends.

[Jerry VanOoteghem]

A friend of mine had the same trouble with a Reeder head. It's not that the head gaskets are bad or made wrong, it's more that the combustion chamber form ignores the traditional head gasket fire ring shape... or so it would appear. I don't know who made the head in question so I'm not throwing blame at anyone in particular.

[Moxie26]

Curiosity... Put head on block without gasket, loosely install a few bolts, Crank engine over by hand. See if valves will clear the depressions in the cylinder head.

[Mike Howell]

The new production copper head gaskets are slightly different from the old style copper gaskets, and address the fit problems you have found with the excellent Prus head. I ordered mine from Langs recently and it fits correctly.
Thank You! to who-ever modified the new gaskets. It will save a lot of time for those of us who have been unfolding old style gaskets, trimming away the center material, and then refolding the copper to better fit the combustion chamber and clear oversize valves.

[Dan Hatch]

Are bolt holes clean at bottom? Be sure bolts are not bottomed out.

[Allan]

If you are using new head bolts, Dan's suggestion is right on. The bolt holes should always be cleaned out anyway. If you are using the same head bolts, bottoming out should not happen if the recommended washers are used when fitting an alloy head. However, this may well not apply when fitting an aftermarket alloy head, especially a Z head. As a matter of course, I install these with no gasket first so the bolts can be checked and valves checked for clearance.

Allan from down under.

[DanTreace]

The folded edge of the gasket hangs over the combustion chamber and is not compressed.

The correct placement for composite gaskets is for the seamed edges to face up. The solid surface surface to the block, otherwise the piston compression will force the seams apart if fitted to the block.

Always use a gasket copper sealant, or in pinch a good high metallic content alum spray , coat both sides fully, apply while still a tiny bit sticky.

Lay the gasket seam side up......note the seams. Place two pistons at TDC to align the gasket, the larger oval coolant opening to the REAR.

After assuring the block bolt holes are clear to the bottom, set the bolts and run them down snug, be sure the head fits square with no gasket shift. Now the important part, the bolts must be torqued from the center line of bolts first, that secures the head to the thinnest area between the cylinders. That compresses the gasket fully in the critical area. Only then work outward and in a pattern shown.

[RajoRacer]

Doesn't the larger opening go to the rear, Dan ?

[DanTreace]

Oh Hooey. Sure missed that one, you’re right. So just edited that post to correct orientation.

[Lexveen]

Well, thank all of you for all your suggestions.
With the “Sherman” style I indeed meant the Prus head. I bought the head together with a new copper gasket from Snyders. I have bought a great lot of parts from Snyders and never had any problems, so I was quite confident it would be an easy job.

I did all the checks that are suggested.
The block has been shaved off and is as straight as a pooltable. The head is perfectly made and is perfectly straight too.
The boltholes are all clean, with excellent thread and quite deep, so the length of the thread is about 1.5 times the diameter of the bolt.
The headbolts are high strength ARP and are adapted to the depth of the holes. I laid the head on the block without the gasket and checked that the pistons don’t touch the head and the bolts are not bottoming out.
I lined out the gasket with the head and block. There is only one right position for the gasket considering the waterholes front and rear, so which side is up is determined.
I did not spray the gasket, because in my opinion if the torque on the bolts is right and the seamed edges are compressed between block and head as they should, there is no way gasses can pass, nor can the gasket been blown away. However, it could prevent the coolant leakage, so next time I will spray it.
I torqued the bolts in the right sequence (like Dan said) up to 55 lbs. After one drive there was some coolant leakage along that specific head bolt, but I thought the torque had gone low. After cooling down I retorqued the bolts to 55 lbs. I did that twice.
Even directly after retorquing, coolant and bubbles came from the bolthole when turning the engine over by hand.

The problem I see on the markings from the gasket on the head, is the shape of the copper gasket. The wall between the cilinders is at certain places narrower than the gasket, so the seamed edges simply cannot be compressed, resulting in a blow by. The coolant leakage is an incidental problem, because the seamed edge around that waterhole was not made right.

I laid the used gasket on a standard head and the seamed edges follow the shape on every point. I agree with Jerry VanOotighem it has the right shape for a standard head. But the shape is NOT right for the contours of the Prus head, which is at some places seriously narrower than the gasket.

The solution would be to make the gasket narrower at those places. Then it would fit standard AND HC heads. Given thats not the case, I did some inquiries for a specially made copper gasket that follows the contours of the head, but was shocked by the price: $ 325 a piece.

Second option is to adapt the head to the gasket by welding it up and shaving it, but I hesitate to do that, because the head is so perfectly made and it is costly too.

So….I still don’t know how to solve this problem in an easy and financially sympathetic way.

[DanTreace]

Lex

Good explanation of the issue, and a try to make a gasket (yikes, expensive).

IMO, would try again with a brand new copper gasket, as the one you show is now compromised by squish from use.

And, use copper gasket spray as recommended by Kevin Prus, plus add anti-seize to the bolt theads, copy of instructions below:

As for the small steam hole, since you identified that one spot for seepage, use of a dab of high-temp (750degrees F) Permatex gasket sealer at the spot may do it.

Have used this sealant at the front edge of the block on the water outlet opening, even with milled face, a portion of the front edge had rust depression, so the sealant filled those and no seepage from the front of the cylinder head/ block interface. Rubbed the sealant into the depressions, and then thick copper spray coated gasket placed over.


This Prus head was placed the same way, new gasket and heavy spray of copper coat sealer on both surfaces.

Anti-sieze to the bolt threads, and carefully placed head to prevent shift of gasket, use of the sticky gasket sealer helps to hold the gasket in place, and then lower the head with a threaded lift handle to allow careful placement. The Prus head and gasket on on this T engine has not leaked for 4 years now.

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