Cylinders 1 and 2 out to lunch

[vdubyah73]

You can try pulling the rocker assemblies off that side and checking the torque on the lower head studs. Reassemble and give it another hot compression test. Thats the short cut. The other way would be pull the engine, pull the heads, lap the heads to the cylinders and reassemble.

You going to the arctic circle? A short cut might not be the best way to go. Pain in the arse, I know. Look at the bright side, you're definitely gettin' aquainted with your engine.

Bill

Bill

[chitwnvw]

Engine's out.

I had lapped the cylinders to the heads and matched the cylinders with their heads. That makes this whole episode a little irritating.

Colin had mentioned that I could take the heads to a machine shop and have them do a very slight fly cut to them to ensure I have a flat surface. So unless anyone has anything to add that's what I am going to do.

[vdubyah73]

You can check that yourself by using a permanent marker as machinists dye on the sealing surface of the head. Then use a small amount of lapping compound, spin the cylinder in the head a couple times and clean the head. Use water to remove the compound, if you use brake cleaner the marker will come off. You will be able to tell if you really need to do a skim cut, or just a good lapping.


Bill

[Amskeptic]

With the engine cold, I ran a compression test on #1 and get around 100 PSI with my compression tester, but if I run for 5 minutes and test, I'm getting 45 PSI. So (??) obviously(??) when it warms up a bit something is loosening. I assume it's the mating surface 'tween the heads and the cylinders.

That is classic tightening valve behavior. As the valve heats and expands, insufficient valve-to-rocker clearance will close right up on you prevent the valve from closing securely against the seat. We will not tolerate posts such as, "I checked the valve clearances but I didn't get under there with a .006" blade. . . felt like they had play or sumpin'"
Do it correctly or don't bother. It is a complete waste of your precious time on Earth to skip critical steps. The consequences are more serious than your outrage at my attitude.
Colin

[chitwnvw]

After I had posted that, I had gone back and the valves were .006. My first check was just a cursory, "Is there something way off" look. I was thinking more along the lines that I had botched the initial setting of the valves and that one of them was being held open. Thinking was that the switch to the swivel foot porsche lifters had played a role.

Anyway, here's the pics of the head cylinder lapping.

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[albumimg]770[/albumimg]

My cylinders have some wiggle worm inside the heads, it's far from a precision fit. Is it possible that I had a cylinder come down on the carbon build up area and that when warmed up it allowed leakage?

[Amskeptic]

Is it possible that I had a cylinder come down on the carbon build up area and that when warmed up it allowed leakage?

Possible. My last step before installing head on cylinder barrels is to run a light razor sweep around the sealing the sealing surface of the head holes. Any carbon that is in the vicinity should be cleaned off long before assembly. You really don't want loose pieces flaking off and landing on the sealing surfaces.
Colin

[chitwnvw]

Got everything back together and installed. Fired it up. Let it run for bit. Did the plug pull test. Each pulled plug had a noticable effect on the rpms.

I didn't see smoking guns when I disassembled. I did do a thorough cleaning of the carbon buildup in the head, especially close to where it would seat against the cylinder.