Very low compression test - B27 w/ 885 head

[ThomasE30]

Just did a compression test after fighting a crank no start for a while. Also just replaced some parts that were worn- Newer coil, new plug wires, spark plugs, relays. Engine is getting fuel, spark and having trouble starting. New connector for the injector harness and engine harness (1,3, and 5 were not getting signal, therefor, no fuel)

Compression test-
1: 0psi
2: 125psi
3: 58psi
4: 148psi
5: 65 psi
6: 145 psi

Cylinder 1 plug is very fouled and oily, along with 3 and 5 but not as much as 1. The engine is a 85’ B27 with the 885 top end. It never ran too well before or after the swap. Constant high idle and what I thought was vaccum leak issues.

could these numbers be pointing at something like worn piston rings or another issue like worn cylinder walls? The head is completely resealed and in good condition.

[e30davie]

Those numbers are all over the place. Is your cam timing correct?

[ThomasE30]

Those numbers are all over the place. Is your cam timing correct?

I made sure to redo the timing belt and check it was right. The cam timing marks and the crank marks line up how they should.

is there any way a valve would be causing issues like this?

I will add that when I was trying to get the engine to run before fixing the fuel injector misfire, it would run but very poorly (had to keep gas pedal pressed). Do you think running it while 1,3,5 weren’t getting fuel, maybe something could have happened to cause low compression now?

Never had any bad noises likes knocking, or tapping occur, just normal M20 valve noise.

[e30davie]

Did you set the valve* clearances properly once you put the head on?

[ThomasE30]

Did you set the timing clearances properly once you put the head on?

Pardon my ignorance, but by timing tolerances do you mean the valve lash with a feeler gague?

[hasa]

I would put compressed air from spark plug hole and listen where it leaks. Can be anything. And it likely requires opening the engine.

[TobyB]

+1 for a quick and dirty leakdown test.
t

[packratbimmer]

Not to get your hopes up but is your gauge working consistently? I recently had trouble with mine and the shrader valves were bad and had to be changed. My setup had two valves.