should I be worried

[SigSaurP229]

I have a 1974 or 1975 Evinrude. I picked up cheaply for a donor engine and trailer. I have thus far only been able to do a cold compression test on it. I havent verified spark carbs or water pump yet. My concern is I am only getting about 90psi on the cold compression test which is low but all cylinders are exactly even without even 1 pound of variance. Should I rent a gauge from autozine and rerun the test on a different gauge?

The only gauge I have is a cheapo harbor freight gauge. The seller claimed 140on all three but I knew that was not true. I just find it incredibly odd that there is no variance.

 

[Bosunsmate]

Re: should I be worried

If it runs ok in the water, then great!
Run a decarb through it.
I do that to all motors i buy, i also pull off a bypass cover and check pistons rings on one cylinder on any motors where i can do that.
How many hp is it?

 

[SigSaurP229]

Re: should I be worried

Sorry its a 75hp so i assumed minimum acceptable compression would be 130

 

[gerhand44]

Re: should I be worried

Then I should be ok with my 82 25hp with 95 and 90 psi? Also what would I need to do to get it back to where it should be when it was new?

 

[SigSaurP229]

Re: should I be worried

New numbers this morning. I can tell this motor has not been run in a long time so I went and put a teaspoon of oil in each cylinder.

Numbers with oil are

122
125
130

So putting oil in raised the numbers but we failed spark test on cylinder 2. Honestly thats not a huge deal.

Still should i be worried about the compression numbers.

 

[Watermann]

Re: should I be worried

Those are good numbers considering the age of the powerhead. My 1978 55 HP was 130 /135. Your motor sounds like it has healthy numbers. When doing a cold test hitting the cylinders with a shot of fogging oil should produce the higher numbers.