compression test
 

Greetings,
On my stock 69 912 what should the compression be? Also, when checking the compression should i go in a particular order or leave the plugs in or out of the other cylinders when testing?
thanks,
Confusa

Hello: According to my manual the compression should be 140-170. Anything less than 140 & you are on borrowed time. Remove all plugs first & start with #1. Duke, 69 912.

Removing the spark plugs will make it easier for your starter and battery to crank.

My basic auto class taught me the following:

"Dry" compression measurement gives you general condition of the cylinder's ability to compress the air-fuel mixture properly. If all cylinders are within spec range, then you are probably okay. But if you have any too low, you can do further testing with a "wet" compression test.

"Wet" compression test is perform just like a dry one except you squirk a teapoon of motor oil into the cylinder through the spark plug hole before measuring the compression. This "wet" measurement will tell you if the low compression is due to bad rings (oil temporarily seals the rings) or due to leaky valves and/or leaky heads.

What you will do will depend upon your pocket book. Generally you're looking for even "dry" compression measurements (low-high). Below spec measurements indicate you better plan on some engine work sometime in the future.

Jones Low
69-912