5.7 compression...too high?

[rooferdave]

hello all, I have tried the search function for an answer but have had no joy, I have a trojoan 36' with two mercruiser 5.7 motors, they were made in 1988, hours unknown, carberated, thunderbolt 4 ignition. They have not been started in this boat yet. Ran compression test yesterday and found pretty much 190 psi on 14 cylinders however #4 on starboard and #3 on port were 210 psi. both of which are inner bank 2nd from rear.
My questions are, are these reading good? (thought 150 was the norm) and what is with the 210 readings?. It may be important to note these have not been turned over in 4 years.

The 500 liters of fuel I just found in the tanks is another story "sigh"

great forum all!

 

[JustJason]

Re: 5.7 compression...too high?

Get a small outboard fuel tank and hook it up directly to the fuel pump. Try running the engine, if it does run let it warm up, and if all sounds good, rev the snot out of it, up and down.

Then retry your compression test with a different gauge.

There is nothing wrong with 190+ psi, just higher than you normally see in a boat motor.