roundman

you should crank the engine until the maximum pressure comes up on the gauge for each cylinder and this might take more than 3 cranks or so. also, do you have all the plugs out and the throttle blocked wide open and the coil wire grounded with the engine up to temp???

Dbeck002

i did not have the throttle wide open, the engine was warm and i only removed one plug at a time.


should i remove all the plugs, while the engine is still warm and leave the throttle at WOT?
i unplugged the coil so the engine will not fire.

roundman

the only real way to get a good accurate compression test is to bring the engine up to normal temp and then remove ALL the spark plugs as quickly as you can. then block the throttle wide open and GROUND THE COIL WIRE, so you don't fry the ignition system.
then screw the tester into each plug and crank the engine watching the gauge until the max reading is obtained. write this number down and go the the next cylinder until you get the readings from all 8 holes. you have to have all the plugs out to accurately get a true reading on each individual cylinder. this lets the starter spin the engine faster and it's only working against the one cylinder where you are doing the testing.

Dbeck002

this may sound dumb but whats a good way to ground my coil? thanks for the info.

roundman

remove the coil wire from the distributor end only and then find a stud or bolt to ground the wire to or use a jumper wire from the end of the wire to a chassis ground point. make sure the wire stays out of the way of the fan and belt.

Dbeck002

ok awesome, thanks for the info DOOD.