Gasket Sealers

[4sfed]

The newer gasket material probably is not as forgiving of positively dimpled or convex areas around bolt holes in the deck, i.e. conformable. A solid copper gasket would likely demonstrate this problem even more quickly.

The block that I have (which is considered a race block) has different OD countersunk areas in certain locations which I believe indicates that Ford dotted their I's and crossed their Ts with respect to understanding and compensating for this type of deck distortion. I understand that clamping force needs to be increased in many applications.

The circled holes have countersunk diameters approximately 2mm larger than the others (roughly 11.5 versus 13.5 mm).

711M DECK.jpg

I don't think it has anything to do with deck deformation. Those holes are typically counterbored for sleeves to align the head . . . with matching holes in the Cometic gasket.

[Kevin Johnson]

The newer gasket material probably is not as forgiving of positively dimpled or convex areas around bolt holes in the deck, i.e. conformable. A solid copper gasket would likely demonstrate this problem even more quickly.

The block that I have (which is considered a race block) has different OD countersunk areas in certain locations which I believe indicates that Ford dotted their I's and crossed their Ts with respect to understanding and compensating for this type of deck distortion. I understand that clamping force needs to be increased in many applications.

The circled holes have countersunk diameters approximately 2mm larger than the others (roughly 11.5 versus 13.5 mm).

711M DECK.jpg

I don't think it has anything to do with deck deformation. Those holes are typically counterbored for sleeves to align the head . . . with matching holes in the Cometic gasket.

I agree that this is a possibility however those sleeves are not present on the exploded parts diagram of the engine for spares and the factory manual explains that gasket alignment tools should be created from old bolts with removed heads and screwdriver slots. These tools are to be used at diagonally opposite bolt positions at the corners.

The Renault engine does definitely have these sleeves and they are listed in the parts catalog. In addition Renault specified various tools over the years to properly align the head, which is much more critical due to the camshaft being in the block and the lifters in the head.

[Dan Timberlake]

I don't think a "static" coolant leak is the result of some esoteric problem, but......Sometimes head gasket problems arise from the thickness of the cylinder head.

In the days when Nascar etc actually used sort-of-production parts some engine families seemed to benefit from "studding" the head in strategic areas to provide more clamping force for head deck areas that were too thin to provide unifirm clamping by themselves.

[4sfed]

I don't think a "static" coolant leak is the result of some esoteric problem, but......Sometimes head gasket problems arise from the thickness of the cylinder head.

Good point. These heads have been around a long time and some resurfaced multiple times. Runit, do you have a measurement of the head thickness on this engine?

[Kevin Johnson]

Yes, I apologize for completely skipping over that he mentioned using 65 ft lbs.

When the head was skimmed were the bolt seats in the head spot faced to make them parallel to the deck? If the tension is not exerted along a true normal vector it will not only not apply as high of a clamping load but there will also be a bending force which will asymmetrically distort the surface around the bolt holes.

I hope that is not too esoteric -- at some point I read that a large percentage of fastener problems could be traced to the clamping force not being normal to the surface.

http://www.te-co.com/Spherical+Washers+ ... 66-C-.aspx Spherical washers might be a temporary fix. I do not know how much room is available in the head.