What to expect with head removal

Dauntless or 134. I'm guessing Dauntless...

Rust stains and/or burn marks often indicate where a bad head gasket was leaking. I'd guess that is what you will find becuase a head gasket could give you low compression on all three cylinders one bank, but it would be odd to have a bad valve in each cylinder on just one side.

If you have burns or cracks around the edges of the valves or valve seats, that's bad. If you have a valve that's sucked up into the head, that's a recessed valve seat and it is also bad. A good cylinder head shop can fix these things.

 

Didn't someone say awhile back that this can be caused by the distributor being installed incorrectly? Kinda rings a bell.

 

would do a compression check before pulling the head.

 

Might give us an idea what the compression readings were. You can try putting a little engine oil in the cylinder and running the test again. No change in the readings will verify that the problem is above the pistons. While the first thing I would suspect in a multiple cylinder failure is the head gasket, a plugged jet(lean mix) run with an aftermarket manifold(left bore runs the left bank,right runs right bank) can burn more than one exhaust valve in the head. Again, I would like to see the compression numbers.

 

Dan when I rebuilt my engine, I did it for the exact same reason you are, I ran a compression test and it came out fine, the ignition was flawless, the engine ran perfect for about the 1st 20-25 minutes, once it was totally warmed up and the block saturated with heat it would run really rough on all 3 cylinders on the passenger side. When I disassembled the motor what I found was a blown head gasket, the gasket was leaking fom cylinder to cylinder, so the fuel was contaminated and compression was lost. The head gasket had burn marks in the spaces between 1-3 and 3-5 cylinders, the block was fine but the gasket was toast and the head needed resurfaced because engine gases had eaten a small groove in the head surface.

 

Ok, we will get to the comp test in a minute. First, all your numbers are high enough to fire, so I'd look elsewere for your problem. Given that you are running a stock intake manifold(you are, arn't you?), I would double check the dist. to insure the wires are correct and the dist is timed to #1 cylinder and timed properly. As for your compression test. I'm somewhat suprised at the amount of pressure jump in #5 and #6 cylinder. I am thinking you might have added a tad too much oil, pumping the compression a bit higher than it should be. However you have two low cylinders on opposite banks that increased compression when you sealed the rings, which kinda blows the burnt valve/head gasket theory.

 

JeepDaddy sort of covered this; maybe it bears restating.

That you have some compression in all cylinders does not indicate a burnt valve or a blown head gasket. With a burnt valve, you'd see a single cylinder with way lower compression, like 50 or 60. If the HG is blown between two cylinders, you'd see two adjacent cylinders that are low. Other head gasket leaks would give you water in the oil, bubbles in the radiator, and so forth.

To me, that looks like a tired engine with worn rings. In top shape, you'd expect the engine to have readings within 10-15 psi of each other on all cylinders. Worn rings can lead to other problems like oil-fouled plugs. I'd expect your misfiring problems aren't related to the compression, but are from some other cause related to spark or fuel. Even a tired engine can be made to run on all cylinders, at least for a while.