198 compression question

Make sure that your compression test method is OK. Best to remove the spark plug tubes and use a screw-in gage. An old "press-in" gage w/ the tubes in place is asking for erratic readings. If you get the Harbor Freight kit like I have, you can easily connect an air hose in place of the gage and apply 20 psi w/ the piston at TDC and search for the leak. You will hear and/or feel air flowing out of the crankcase (bad rings), intake (bad I valve), or exhaust (bad E valve).

In my experience, if the rings are truly bad, you will have a lot of blue smoke. If the valves are so bad you don't get any compression, raw gas will flow thru and your spark plugs will be perfectly clean looking. Using a vacuum gage while idling is another way to check valves. If the needle jumps wildly, that can indicate a bad valve.