Compresson Test

JT FORD

JT FORD

Senior Member
Going to do a test on my 8BA engine. Have some questions? No. 1. does it make any difference if I remove one plug at a time and test and reinstall or remove all the plugs and test with all plugs removed?? No. 2

should I remove the feed line from the tank to the fuel pump so there will be no gas going to the engine, with all the gas engine would be flooded! Engine warmed up, trodduol wide open, coil wire pulled.
 
Remove all of the plugs; you'll get a more accurate reading because he engine will turn faster and it's easier on the starter.

I have never disconnected the fuel line when taking a test; I do disconnect the coil and block the throttle open. Because all of the plugs are out, it won't develop sufficient suction on the intake stroke to draw in a problematic amount of fuel.
 
JT, All plugs are to be removed to ensure that the engine will spin fast enough to provide a good consistent reading on all cylinders. The carburetor will have been topped out by the fuel pump, thereby closing the float valve to prevent overfilling of the carburetor by the pump. With the throttle wide open, there will be zero vacuum to draw in fuel from the carburetor.

Watch the gauge as you spin the engine, the compression reading will pump up to it's maximum potential within 3 compression cycles. Record this reading for each cylinder, and compare results to each other.
 
Thank You fellows for the advice. Its just been almost 70 years since I did a test like this........
 
You must log in or register to reply here.
Back
Top