Good evening all,


I've starting doing routine maintenance on my '54 Savoy, and decided to do a quick compression check after warming up the engine. With the throttle open, ignition disabled and plugs in all of the cylinders (save for the one being checked) I found that all of the cylinders were even across the board, at 50psi.


The engine starts fine, doesn't smoke, nor does it have any coolant in the oil, or vice versa. I'm not sure when the last time the valves were adjusted, but there's a tag on the block that shows the engine was rebuilt by Schedler in Fresno, CA sometime in the 80's. It doesn't seem to lack power, but I'm a bit worried by these readings. What could cause such low readings, and not also show signs like a smoking exhaust or fluid leak? Could old oil or miss-adjusted valves give such low readings?


I should mention that this engine also has the original starter, which seems to turn somewhat slow. Would a slow starter affect it that greatly? I'm hoping that's the case, and not a skipped timing chain tooth. I was going to adjust the timing, but I'm not sure if I can use a 12v light on my 6v positive ground system.

 

Good Day.

A slow starter with plugs in can give low readings. You did everything correct except leaving plugs in.

Try again warm with all plugs out, if still low add 2 tablespoons of motor oil to a cylinder at a time and check that cylinder. Adding the oil will temporarily seal the rings and if the reading goes up dramatically then rings are a problem.

The next thing to try is an air test. You'll need an adapter from air hose to spark plug hole. Best to do with piston at TDC with both valves closed. If you hear air...

At exhaust pipe = leaking exhaust valve.

At carb/ manifold = leaking intake valve.

At crankcase breather = rings leaking by.

Good Luck, Dan.

 

Morning Y'all... Good thinking Dan.....

Woody... That dose seam to be a little low on the compression... I believe that it should be closer to 100 +/- PSI.... Timing should be like 2* BTDC for those old 215 motors, And the compression ratio was around 7.10 C.R. in O.E.M. form.
I would Cover the basics first also... Valve adjustment ( I dont Remember What that Spec is Sorry) and pull all the plugs for the test, and make sure it is spinning up to speed when you check it.
Other than that. Try some of the stuff Coronet 500 suggested...
Glad it is running good and smooth at this point. Sounds like you done good with what you spent....
Keep us posted

Added: Just a Rule of thumb. But there are lots of other Volume that can come into play... Atmospheric pressure at sea level is about 14.7 PSI. So a 10 to 1 compression ration would give 14.7 x 10 = 147 PSI.