Thanks Cantflip...That's excellent advice in my book. I'm having a hard time believing the motor is bad. This car is so clean and has had such good care over it's 48 years, I've got to believe it's sticky valves or yes...I've done something wrong. I caught something you said "all plugs must be removed or throttle opened" to get a valid compression test? I did one at a time and didn't touch the throttle. I've been doing minor repairs on cars for 40 years now...never ever have claimed to be an expert at anything. In fact, I know just enough to get myself in a lot of trouble. Care to expound on how a proper compression test should be done? I have the screw in type comp. gauge....with two different sized threads and hose...rubber o-rings look good. I screwed it in each spark plug hole hand tight. I removed spark plugs one by one to do compression test and then replaced the plug and moved on to the next. That's how I got numbers. Perhaps I should repeat with a better/correct method?...One thing I didn't understand...I smelled gas and the last few readings on #5 and #7 cylinders, the plugs were wet. How could this be without touching the gas pedal? I started the car after the 8th cylinder reading...and it was obviously flooded as I had to press the accelerator pedal to the floor to get it started.
Bob
Compression test... do the wet test at the same time...
1)Pull all plugs to take load off the starter.
2)Disable ignition (take coil wire off cap and secure to a ground source on the engine.)
3)Strong battery, on a charger if available. a battery that is weakening will give false lows at the end
4)You will want to crank all cylinders even number of times, between 5 and10 revolutions. I like 10
5)Before cranking, wide open the throttle... it assures airflow, but more importantly breaks vacuum draw at the carb and cuts fuel...washed cylinders will read lower. Foot on floor, key to crank, listen for 10 passes...read gauge.
6)Use a transmission funnel, a piece of hose or my favorite.dip a soda straw into the oil bottle. finger on the end to hold the oil until you get the straw end into that tough spark plug hole. A teaspoon is enough... don't worry about how much after that... just relates to the mess you have to clean when finished. Motor oil of what ever you have is fine, no need to get cute or expensive.
The key you are looking for is even readings within 10% of each other is ideal. Keep your readings logged in order and as dry/wet... once you wet test, you cant dry test without giving a good burnoff run around the neighborhood... there may be a little smoke. Do all the cylinders and you will see the wet test raises all readings 5 psi or more... normal, because oil is the final seal for the rings... any readings the go much beyond 10 psi show a ring sealing issue... but washing the cylinders with fuel could also explain the lower dry reading... wide open throttle is important. If wet compression is even, give her a good run... warm up and drive a while at light load as much as you can... nice highway type cruise for example... you dont want to idle much or get on it during this so you don't get too much fuel in the cylinders. Even a well oiled 10-20 mile trip will help the rings reseat a little... and could make a real change.
Some will tell you to do the compression test on a warm engine. I would start it and run it maybe a minute tops to help remove the plugs... but try to get the plugs and compression testing done on a hot engine before it cools enough to change readings is unlikely. Know that your numbers are cool cylinders and will improve when running. Some newer engines have even lost compression that once regained by wet testing seems to stay... that is likely fuel washed cylinders and could happen to an older engine as well. If the wet readings are reasonable... I would definitely run it as is this summer... you can retest and decide what you want before the winter sets in. You may even get a surprise from the end of summer readings.
It may be too late now, but I keep the plugs in order and give them a careful eyeball. Reading the plugs can also give excellent information and clues as to why cylinders are uneven.
One more thing, this should have been the first test BTW. Wide open throttle to cut fuel and crank for several revolutions while listening carefully for the engine to speed up and slow down. If it has a rhythmic change that happens consistently... then I do compression testing to look for uneven cylinders... If it had no change and good power, I wouldn't even bother with compression testing and I wouldn't react to the results of your test. If you have the plugs back in... try this first... then go ahead and give yourself some piece of mind by doing the readings... all information you gather will match up and you may decide none of this mattered in the first place. If everything points to a low cylinder or two and wet testing doesn't help we will happily walk you through leak down testing... but you will need a small tank compressor minimum to perform that test. Oh and a leak down gauge... which shouldn't break the bank, but is more than the average home user would generally have.
