2011 at the Hammond Barn

[Alex Blair (RIP)]

Originally Posted by Bob Carriere

The cylinder balance test from GM calls for grounding 4 plugs and running engine on just two cylinders.....something I have yet to see.....

NOTE...engine was never rebuilt....but was a good running engine....as early as before Xmas it ran very smooth......

Stuck valve I believe would make different noise if stuck open.... not sure if we would hear anything if stuck closed....but if closed something would happen to the push rods..... may be it has....?

Is it possible....just maybe..... with the engine stored at -30C that some small amount of water could have frozen in one of the drilled out holes in the crankshaft...the ones they drill at the factory to balance the counter weights....... and we did not run the engine long enough to really get it to operating temp.... holes are about 1 1/4 inch wide...up to an inch deep.... if it held water frozen it might be enough to unbalance the engine....

Strange is the engine ran fine....vacuum was good.... picked up revs easy with no backfire..... but vibrated in a very low frequency rumble that picked up with higher revs.

Bob

Bob..If it was a stuck valve you would get a racket from the push rod/lifter area..but anything is possible..bad gas..accelerator pump..did you do a compression test..??
That will tell you right away..Do a dry one and then squirt in a little motor oil (wet test) and that will tell you if it is a valve or a ring or could even be a piston skirt..
That would account for your balance thoughts..but a wet and dry compression test will tell you lots.
With out doing that first you are poking in the dark..
(If you need a compression testing gauge,I have one here kicking around some where ..you can borrow it)