What tools are needed to do a compression test?

[randomact]

I would like to know how to compelte a compression check on my 70HP motor force. I am wondering what I will need to know/tools to be purchased to test the motor properly. Can someone give me some recommendations here. Thanks

 

[bowhuntrrl]

Re: What tools are needed to do a compression test?

You will need a compression tester/gauge and a spark plug wrench !! Take out the plugs, and make sure that the ignition leads are grounded to prevent damage to electronic ignition. Then screw the gauge into the cylinder, turn engine over with starter for 4-5 revolutions and read gauge. I feel it is best to check compression with carbs set at full throttle and choke open. Repeat for all cylinders. Reinstall plugs.

 

[4runneradam]

Re: What tools are needed to do a compression test?

Harbor Freight has a few inexpensive compression testers. I use one and it works just as well as the expensive ones. Here's one for $5!

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92697

 

[Ford3316]

Re: What tools are needed to do a compression test?

bowhuntrrl,
What is the best way to ground out the ignition lead?
Thanks, Ford 3316

 

[bowhuntrrl]

Re: What tools are needed to do a compression test?

bowhuntrrl,
What is the best way to ground out the ignition lead?
Thanks, Ford 3316

What I did is made up a set of jumper clips. I bought 4 large alligator clips and wired them with about 1' lengths of black 14 gauge wire. Then I tied them all together with a wire nut or whatever means (soldering). One clip goes to ground, the rest to the spark plug body near the electrode. Just add more jumpers to the equation when building it to compensate for the number of cylinders on your engine.