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tubman · 09-04-2016, 10:04 AM

Any of you that have been following my threads about my "adventures" with my used Edmunds heads knows that I massaged them until I had 62 cc chambers and (I thought) .045 "squish". I measured this by putting 5-6 foil balls on each piston top and turning the engine over and then measuring them. To do this, I installed the heads with the used Mercury script gaskets that had been on the engine and looked to be in remarkable good shape. I didn't torque the heads, just cranked the bolts down good and tight with a 1/2" drive ratchet.

After everything, the engine starts and runs great, but still has an external head gasket leak on one side. To correct this, I got some "Iron-Tite" ceramic sealer. To make a long story short, their procedure requires running the engine for at least 60 minutes at operating temperature. While doing this I noticed a "tapping" sounds coming from the engine after it was fully warmed up. It sounded like a loose lifter, but I listened with a tube down into valve chamber, and I don't think that's the problem. The only things I changed were the heads, so it must be them. My neighbor is an avid snowmobiler and he showed me a trick they use to check for rod stretch. We stuck some .060 diameter solder through the plug hole and over the piston top and turned the engine over. The results were that all of my cylinders have a squish dimension of between .022 and .031". this is about .020 less than I have seen recommended here. The heads were installed with new "Fel-Pro" gasket coated with spray-on "Copper-Coat" and torqued several times.

It is my belief that the tapping is one or more of the pistons "kissing" the head. My next move is to go back to the shop and go through my stash of gaskets and see if I can find some thicker ones (I need .020 more; I have some copper gaskets somewhere that I seem to remember being thicker). The only other solution I see is to grind .020 out of the chambers. That seems to be a lot of work on a set of marginal heads. I welcome your thoughts on this. As a point of reference, all cylinders have about 170 lbs of compression.

Oh yeah, the Iron-Tite" didn't stop the leak; more on that later.

09-04-2016, 10:04 AM	#1
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 11,623	"Squish" problems Any of you that have been following my threads about my "adventures" with my used Edmunds heads knows that I massaged them until I had 62 cc chambers and (I thought) .045 "squish". I measured this by putting 5-6 foil balls on each piston top and turning the engine over and then measuring them. To do this, I installed the heads with the used Mercury script gaskets that had been on the engine and looked to be in remarkable good shape. I didn't torque the heads, just cranked the bolts down good and tight with a 1/2" drive ratchet. After everything, the engine starts and runs great, but still has an external head gasket leak on one side. To correct this, I got some "Iron-Tite" ceramic sealer. To make a long story short, their procedure requires running the engine for at least 60 minutes at operating temperature. While doing this I noticed a "tapping" sounds coming from the engine after it was fully warmed up. It sounded like a loose lifter, but I listened with a tube down into valve chamber, and I don't think that's the problem. The only things I changed were the heads, so it must be them. My neighbor is an avid snowmobiler and he showed me a trick they use to check for rod stretch. We stuck some .060 diameter solder through the plug hole and over the piston top and turned the engine over. The results were that all of my cylinders have a squish dimension of between .022 and .031". this is about .020 less than I have seen recommended here. The heads were installed with new "Fel-Pro" gasket coated with spray-on "Copper-Coat" and torqued several times. It is my belief that the tapping is one or more of the pistons "kissing" the head. My next move is to go back to the shop and go through my stash of gaskets and see if I can find some thicker ones (I need .020 more; I have some copper gaskets somewhere that I seem to remember being thicker). The only other solution I see is to grind .020 out of the chambers. That seems to be a lot of work on a set of marginal heads. I welcome your thoughts on this. As a point of reference, all cylinders have about 170 lbs of compression. Oh yeah, the Iron-Tite" didn't stop the leak; more on that later.