I'm going to do a compression test on the cylinders, just for the heck of it ( not because I'm having a problem ).

Whats the compression specs for a new 351c.i. ( 5.8 )?
Whats normal range and bottom "ok" range. I know they should all be within a few pounds of each other, right?

Anything I should know before I attemp this?

Thanx
Jim

 

No one has any idea what the compression range should be?

 

When you do the test make sure your coil is disconnected, and fuel pump fuse pulled, throttle body butterflys open, and all the spark plugs removed.

Because you do not want spark, you don't want fuel, and you need air to the cylinders, the engine needs to rotate a equal rpm for each cylinder you test.

This is just a rudeamentry compression rule....When the engine puffs by the fourth time your dial generally should be maxing out on pressure for that cylinder.

What that exact pressure is no one knows. make sure all cylinders are with in 10% of each other. anything over 70 psi is compression enough for a gas engine to run. 160 - 180 psi is approx on most stock engines I have checked and that to can vary even more.

if the last cylinder seems lower than the rest you can add a squirt of engine oil through the spark plug hole and compression will raise.....provided your valves are okay.

A search on the internet for compression testing will bring you tons of info.

However my favorite cylinder test is the leak down test and if you can't afford snap-on then Auto Zone or oriellys make a real cheap one that works for the home mechanic for around $45.00. Instructions come with the tester and on the net.

Have fun and good luck to you....

 

Thanx for your help.

Yes, I found a good article on how to do the test and what the different results might mean.

 

You should post a link to the article for the rest of the people that might search this topic here in the future!!



Matt