Compression Test Path Forward Opinion (1 Viewer)

[bamelanc]

1F compression test. 114k on odo.

Cyl 1 - 110 psi
Cyl 2 - 108 psi
Cyl 3 - 101 psi
Cyl 4 - 111 psi
Cyl 5 - 114 psi
Cyl 6 - 120 psi

If I read it correctly, 150 psi is what it should read with a minimum of 128 psi.

I didn’t get a chance to perform the troubleshooting of determining if it was the valves or cylinder.

 

[middlecalf]

Tested with the throttle wide open? If not, redo with throttle wide open. If so, squirt a little oil in each cylinder and retest and report back. Also consider a leak down test.

Is this a current running motor?

 

[Skreddy]

As said; throttle should be wide open. How does it run or is this a non-runner? Smoke, noise, etc?

 

[bamelanc]

Tested with the throttle wide open? If not, redo with throttle wide open. If so, squirt a little oil in each cylinder and retest and report back. Also consider a leak down test.

Is this a current running motor?

If having the gas pedal mashed is the same as having the throttle open, then yes. Choke was also open as the manual requests. All plugs out.

Runs well IMO but idles rough. If tach is correct, I can’t get it to idle lower than 1000 rpm or it will sputter out.

 

[Skreddy]

Have you checked for vacuum leaks? Not running below 1000 rpm would lead me there as vacuum isn’t passing through the carb to pull fuel but instead is coming in somewhere else.

But yes, throttle to the floor and choke open/off/no choke.

 

[bamelanc]

Have you checked for vacuum leaks? Not running below 1000 rpm would lead me there as vacuum isn’t passing through the carb to pull fuel but instead is coming in somewhere else.

But yes, throttle to the floor and choke open/off/no choke.

No, not yet. Just starting to dig in to rough idling.

Changed out cap, rotor, cables and plugs last week. Seemed to help slightly, but still idles rough.

 

[bamelanc]

Not sure if this is applicable but maybe it will give some of you some ideas on what’s going on inside the cylinder.

These spark plugs have about 50 miles on them. Note the fouling of the spark ends.

 

[mattressking]

Everything mentioned above is good info, I’d just add in a valve adjustment as well, but the cylinders are somewhat even, so a head gasket doesn’t seem to be a glaring issue. Likely rings, but as said above, squirt some oil in and retest. Do a vacuum test and if you can get it to idle under 1k, either start looking at carb and linkage or find the big vac leak, or both. Sounds like your linkage isn’t returning closed on carb, try to manually rotate it shut and verify butterfly is closed, then use idle speed screw to adjust initially.

 

[rainingagain]

Not sure if this is applicable but maybe it will give some of you some ideas on what’s going on inside the cylinder.

These spark plugs have about 50 miles on them. Note the fouling of the spark ends.View attachment 3237023

Only 50 miles on those? Without more miles on the plug, I can't really tell if it's on it's way to fuel fouling or oil, but #2 looks to be burning some oil to me. Valve guide too sloppy or a broken/worn ring possibly. Do you get any blue smoke at first startup? Or when under a load? #4 looks like it's on it's way to being a number #2, followed by #6. Actually they all look a little brown. Can't get the idle under 1k...did you crank up the fuel ratio or mess with the timing to try and compensate? Do you get some black smoke when you stomp on it (i.e. it's running rich or the timing is to retarded)?

 

[SteveH]

Are you at any elevation above sea level? Those numbers aren't great, but wouldn't be bad at 7000' elevation.

 

[3_puppies]

was this a hot/warm engine or cold?
have the valves been adjusted?

 

[pjohnson]

Does it smoke on startup?
Does it smoke while running?
Does it smoke when you apply throttle or let off throttle?