Compression

would someone please tell me w

would someone please tell me what the compression should be in a 1977 350 260hp?

"JB
with all the plugs out 12

"JB
with all the plugs out 120 to 130 real good,
70 lbs bad."

How about a 1984 Crusader 270

How about a 1984 Crusader 270 compression?

"For All Gas motors that are f

"For All Gas motors that are found in Boats,.....

200psi is High,.... Probably a Hot Rodded motor.....

135/195psi is an Average # seen......

Anything below 100psi is a Dead cylinder......

And,......
With a Compression Test,.....You're Not looking for a particular #,.......
You're looking for #s that are Close to each other,.....
No More than 15% Differences between any 2 cylinders....."

I have checked each cylinder o

I have checked each cylinder on my Crusader and each one reads around 90 except 1 which reads 116.
The engine ran pretty hot for about 20 minutes last year (running from a storm). Ran rough for a short while after that and now will not crank at all.Not sure but thought rings may be stuck.Any help would be greatly appreciated.

Lamar

"Ayuh,......

That's sou

"Ayuh,......

That's sounds like it's time for an engine Rebuild......"

When originall y did this test

When originall y did this tested with the plugs in. Going to redo with plgs out but wondering what kind of differences this would give?

It should be a bit higher. Be

It should be a bit higher. Be sure the throttle is open.

Jeff

"Here is what you are looking

"Here is what you are looking for from the Crusader Operation and Maintenance Manual

"A uniform variation of +/- 20 psi, from 130-170 psi is permissible, the compression of all cylinders should be uniform within 10 psi.

A reading above normal indicates excessive carbon buildup (or water in cylinder)

A reading below normal indicates leak in cylinder gasket, piston rings or valves.

A low even compression in two adjacent cylinders, indicates a head gasket leak.

To determine between rings vs valves, squirt appx tablespoon of oil into cylinder, redo test if pressure remains unchanged valves likely culprit, if pressure increased 10 pds or more rings likely culprit.

During test if pressure fails to climb steadily and remains same during first two successive strokes, but climbs higher on the succeeding strokes, or fails to climb during entire test, it indicates a sticking valve.."

I essentially summarized what it says in the manual or I would still be typing tomorrow...

hope that helps."