750 combat leak down test

Want an opinion. While doing a leak down test on my 750 combat engine I can hear air leaking in the rocker box, both intake and exhaust when both valve tappets have a gap, valves fully seated. Pressure on the leak down guage is 10psi. What are the possibilities - worn guides, worn springs, head gasket or what? Valves are fairly new black diamond done at Rabers with new seats and one new guide - left exhaust. I reused the springs that have around 35,000 miles as the height was OK at the time. Head gasket is not leaking externally, sprayed some soapy water atthe cylinder/head joint and no bubbles.

Internal head gasket leak to pushrod tunnel.

kommando said:

Internal head gasket leak to pushrod tunnel.

Click to expand...

Yes, I thought that also. Would be nice if that's all it is. Just ran the compression tester again with throttle wide open and about 8 times over the compression stroke. Getting 170 to 180 psi now, so the rings are likely good.

illf8ed said:

kommando said:

Internal head gasket leak to pushrod tunnel.

Click to expand...

Yes, I thought that also. Would be nice if that's all it is. Just ran the compression tester again with throttle wide open and about 8 times over the compression stroke. Getting 170 to 180 psi now, so the rings are likely good.

Click to expand...

You would also be able to hear air leaking by the rings in the cylinder head.
You can put a couple OZ of oil into the cylinders to slow the leakage by the rings for a minute if that is where its from.

But illf8ed is probably right. a head gasket leak into the pushrod tunnel.