Compression too low?

[RusteeNutz]

Hi everyone

As I continue to work on the 54 3100 I purchased, I am wondering what to do with this 235 it came with. I removed the 235, but before doing so, I checked the compression and averaged about 80#'s on all cylinders.

From what I have read, 130 is about where it should be when in good working order. Will this engine need to be rebuilt, or does it still have some life left in it?

It does smoke some when running, but did not have a chance to take it on the road much as it wasn't in the safest conditions; leaky gas tank in cab, sparking battery, dodgy suspension etc.

Plan is to upgrade to v8, but wanted to know whether this sixer still have life left in it for possibly another donor.

Thanks in advance.

Ralf

[Dan in Pasadena]

It's tired, but most important is your cylinder pressures are the same across all cylinders. It smokes a little could be rings or could be valve guides.

If you're truly in a bind for money I'd suggest cleaning it up, reinstalling while knowing you've gotta save for a rebuild soon.

If money isn't a huge issue, I'd rebuild. Beware of anyone telling you a valve job will suffice. It might ... for awhile but better sealing valves put more pressure on already worn rings.

[Henry50]

Did you pull all the plugs out and open the throttle when you checked the compression? Have you adjusted the valves?
What color is the smoke?

[mr48chev]

Originally Posted by Henry50

Did you pull all the plugs out and open the throttle when you checked the compression? Have you adjusted the valves?
What color is the smoke?

Good point. A proper compression test is done with all spark plugs out and the throttle propped wide open and choke wide open.
I'd
With the compression being even I don't think you have valve issues but the rings may be pretty well worn.

If it runs fairly decently and doesn't fill the road with smoke I'd tune it up and maybe put at least 30 weight oil in it and run it while I was sorting it out and figuring out exactly what I wanted to do with it. Driving is easier than pushing when you go to move it around until you are ready to redo it.

As far as selling the engine when you are ready. I'd just advertise it as a running rebuilder when the time came. I'd put the engine up for sale just before I was ready to pull it and let prospective buyers listen to it and even take them around the block in the truck. Mark right on a printed out bill of sale : Engine is sold as a rebuilder and there is no warranty or guarantee. You might even note the compression and oil pressure at the time of sale but make no doubt that you are selling it as a rebuilder and not a usable as engine. Make two copies of the bill of sale for it and keep one in your file with the buyer's signature and yours on it. That way the buyer can't go bone headed and install it and then whine or sue you because it isn't perfect.

[RusteeNutz]

Thank you for the responses.

Did not pull out all spark plugs at once. Removed them one at a time, and tested each cylinder 3 times. Also, did not open the throttle wide open. It might appear then, these numbers aren't 100% accurate and with the engine already removed, I might not know the true crank compression. Though, I did find some comfort seeing they were all pretty close to each other.

OK, at least now I have some options--and know what to do next time. Thanks for helping me through my thought process.

Ralf.