For those that have been helping - Thanks!
I put the head together last night with the copper coat still tacky and things seemed to be going well until I did a compression check.
No change from where I started:
Cyl1 - 45
Cyl2 - 45
Cyl3 - 40
Cyl4 - 30 (audible leaking sound on the compression stroke)
This time the manifolds were off when I did the compression check and it was apparent that the leak on the compression stroke was at the intake valve. I took the head off again and found that the intake valve had about 0.012" clearance, but was not closing until well into the compression stroke. I don't have a valve stem grinding machine, but I do have a lathe a grinder and some V blocks so I shortened the valve stem in increments of 0.005". I have now taken about 0.015" off the stem and I have the intake closing when the piston is 3" from the top of the head on the compression stroke. (Book says it should be 3 1/8", so this is a little late) The intake valve opens after top dead center when the piston is about 0.1" above the block. (Book says it should open when piston is 0.25" above the block so it is also opening late)
If the intake opens and closes late, adjusting stem length can make one timing event better, but the other worse. I have it in a middle ground, but is this indicative of a cam problem?
Decided to take a vacation day today and play a little more. I put the head back on with the valve ground as above and the original gasket hand snugged down. Cyl4 now has 45PSI compression...
I am going to check Cyl3 valve timing now.
Joe : What's confusing me is that you stated that "I took the head off and found the valve had about 0.012" clearance". Why would you take off the head to measure valve clearance??? If you have actually 0.012" of clearance between the valve stem and the lifter and the valve is still not closing, it's sticking in the guide, or the spring is broken or very weak. From what I'm reading, you should now have 0.027" of valve clearance which is about 0.017" too much. Good luck : Bruce
How old is your camshaft? Maybe need a new one or reground.
Also how are the valve springs? Is the valve sticking?
Could even be the bushing at the rear end of the camshaft is worn.
I wasn't clear. I took the head and the valve cover off. I had previously checked the valve clearances and all were about 0.012" when at their largest.
The guide isn't tight, the valve drops right in. Spring isn't broken or particularly weak either. I also tried pushing the top of the valve down and it is being held up by the cam / tappet.
This time I tried the K-W valve timing method based on piston position which is why I took the head off. #3 intake valve was also a late closer, at 2.77" so I have adjusted it to
Right now this is what I have:
Exhaust valve opening (guide says 3.375" nominal 3.3125 - 3.4375 OK)
Cyl4 3.46" (I may tweak this one, but want to check the closing position first)
Intake valve closing (guide says 3.1875" nominal, 3.156 - 3.21875 OK)
Cyl3 2.78" orig, adjusted to 3.03"
Cyl4 2.45" orig, adjusted to 2.97"
or he could be saying, the valve was sticking up .012 over the top of the block. Of course if you do the by piston travel method, you will end up with really big gaps on some valves.
I wasn't clear, by 0.012" clearance I meant what we conventionally call valve clearance, distance from the stem to the tappet.
I realize I can't adjust cyl4 exhaust better without increasing stem length.
Something sounds wrong. I agree with Bruce, if you measured .012 clearance between lifter and valve and it's still not closing properly, the problem is the valve or lifter sticking or weak spring or something.
I would pull the oil inspection pan and verify that all cam lobes look good and that all lifters are rising and falling without restriction. If valve is sticking that lobe might be worn. Then check that all valves aren't loose in guides in terms of wobble and that all valve springs feel good.
.012 clearance is enough that valve should have zero problem closing and seating. There should be a smoking gun somewhere.
Sorry, apparently lots was posted since Bruce did.
If there isn't too much wobble from valves in guides. I would just get new valves and cut all new seats.
I went to my local automotive machine shop and had them grind the face of #4 exhaust valve. That seemed like the easiest way to reduce clearance on that valve and that one had a little pitting so it cleaned that up as well. I lapped it in and now #4 exhaust opens at 3.42" To hit the piston position "spec" for intake valve open would require even more valve clearance so I decided this was a happy middle and it seemed to bring compression back to cyl 3 & 4.
A new head gasket is on its way from Lang's because the copper coat stuck the old one down to the point that removing it bent it up.
Using the piston position method, the valve clearances ended up:
Piston position at which intake valve closes "spec is 3.1875" +/- 0.0313
Piston position at which exhaust valve opens "Spec" is 3.375", +/- 0.0250":
Thanks for everyone's help. I assume having compression will help, but my guess is those two intake valves with the large clearance will make a little noise. We'll see...
(Message edited by 2slow on July 13, 2017)