No head gasket?

[JimmyC]

Hi,

I have the heads off on my 710 and by the carbon marks I suspect I may have had some leakage between the cylinder and heads. How do I make sure I have a good seal here?

Jim

[rmel]

What's your end goal here? Are you going to hone and re-ring?

In any case the standard approach is to hand-lap the heads to
their respective cylinders. Or if $'s are no object get them fly cut.

I've done several top ends and hand lapped with good results.

BTW now that the heads or off, you really can't hand lap W/O
pulling the jugs -- this is a much larger project that comes with
some nuances especially around sealing the jugs to the block.

[JimmyC]

Ron,

#4 cylinder had low compression and some oil fouling of the plug. My original intention was to change just that cylinder/piston/head. I found lots of oil/crude on the cooling fins, apparently from the seals on the pushrod tubes so we pulled all the cylinders and heads to clean the cooling fins and renew the pushrod tubes seals. The parts other than the seals look good, but some of the heads and cylinders have carbon marks that look like they were leaking. We now intend to go back with old piston/cylinder/head on one through three and a new cylinder, piston, and head on cylinder 4. New gaskets and seals.

I am pretty comfortable with everything except sealing between the head and cylinder. My intention there is to lap the cylinder face on a piece of marble and then lap the head to the cylinder. I would like some feedback from someone with experience if this is a good plan, any secrets about how to do it, and anything else we should look at or do.

Jim

[rmel]

A polish on the cylinder is an OK thing to do, I never had one that needed it.

To hand lap the head to the cylinder, lock the cylinder in a vise, apply lapping
compound to the head, place the head on the cylinder and rotate back and forth
checking until done -- it can be time consuming.

Sealing the cylinder to the engine block requires the right sealant. I have NOT
had good luck with Permatex Aviation #3, the viscosity is way too low out of the jar.

The hardest part of this job is cleaning the surfaces.