Compression testing

[Anonymous]

Bear with me guys, I'm going to try and ask this correctly.

I'm going to do a compression test on each cylinder this evening and wanted to know what acceptable numbers I should be expecting?

As some of you know I've been experiencing alot of problems with my engine (hence the engine swap idea). Mostly mysterious white smoke from the breather cap (excessive) and a rough idle. The idle has gotten better but is still rough when I shift it into drive or reverse. My thinking (after replacing MANY parts) is that one or two cylinders are not within compression tolerances causing the rough idle - maybe. And if I can get this worked out my next goal is to tackle the smoke. It could be just a bad oil pump considering my oil pressure is on the low side.


Thanks.


-Chris

 

[weeds]

My last compression test gave numbers above 140 psi. IIRC, they were actually around 160. But it has been too long to give real numbers. These were dry.

 

[Hot 6t Falcon]

While it is important to have reasonably high numbers, it is MORE IMPORTANT to have consistant numbers. i.e. if all of your numbers are in the 140 range (+ or - 10psi) your problem is not compression.

Conversely, if you have two cylinders at 80 psi and the rest at 140 - that will make a ragged idle.

Remember when you do the compression check to have ALL of the spark plugs out and the throttle WIDE open.

Good Luck

 

[Anonymous]

Great! Thanks for all the help!


-Chris