compression test results

All,

I decided to run compression test on my '72 today. No real reason except curiosity.

Here are the results:
Cold/dry: 120-125-75-120
Hot/dry: 120-130-75-125
Hot/wet: 150-155-160-150

Looks like my #3 rings are on their way out, right?

Some other data points:
-valve clearances have been checked and are ok
-plugs are all light tan in color
-NO oil consumption at all
-no smoke from the exhaust
-runs fine, good power, reasonably smooth idle

Should I worry about this? I had the car off the road for several months during the winter and I don't want to do that again while it's warm out.

If it runs ok why worry about it till you have time and the weather is not so nice.
Dose it burn oil?
Enjoy the ride tell then.

Dwight

Runit knowing in the back of your mind that a rebuild is in your future. This winter will be a good time to do it. If it's not burning oil at the end of the season, I'd retest then make the decision on rebuilding this winter.

What Gerry said, BUT keep in mind that it may just be a case of the rings stuck to the pistons and the issue may clear up with some driving. Go have fun blowing the carbon out of it and maybe things will improve! If it doesn't improve, at least you had fun driving it!

Maybe try some Marvel Mystery Oil or other Snake Oil might hasten the unsticking of valves.

Thanks all. I'll just enjoy it for now.

If I may.... how did you go about measuring the compression? Did you do it yourself or have a shop do it?

Also, what does the "wet" refer to?


Excuse my ignorance as I am still learning day by day... Thanks

Torsten, you can pick up a compression guage at any parts place for $20 - $30.

You simply remove the plugs (and the coil wire, or some people ground it) so the car won't start while cranking the engine, and screw the guage into a plug hole. You crank the engine 5 to 6 revolutions and read the results off the guage. Then proceed to the next cylinder, recording each as you go.

Dry usually means before the engine has warmed up, and not putting anything into the cylinder.

Wet is after adding a few drops or an ounce of oil into the cylinder to provide a better seal for the rings.

Comparing both readings (dry and wet) can give you an idea of what is happening with the rings and or valves. However to get a better idea of the valves a leak down test is used.

Other more experienced members can fill in some of the blanks but that's a basic rundown of how to do it.

One thing Bill left out is to hold the throttle open all the way while you do the test.