compression

[bakercheese]

Who can tell me how much compression a good running motor should have ?
bakercheese1949@hotmail.com

[aquasonic]

That is entirely dependent on the make and model.

Improvise-Adapt-Overcome

[bakercheese]

I guess I should have asked if someone knows of a chart or literature telling how much compression various motors should have.

[chris-p]

Again, what motor are we talking about here? Varies wildly.

No charts exist, mostly. Sorry.

IF you tell us what motor is in question, we can help you with an acceptable range based on experience however.

[bakercheese]

How about a 1956 Evinrude 15 hp model 15016

[Buccaneer]

My 15016 had 105 psi compression on the good cylinder,
and 87 psi on the cylinder with the stuck rings.
I presume 105 is "good".

Prepare to be boarded!

[aquasonic]

I am no expert on OMC 15 HP, but I would think that anything over 100 PSI is considered good.

Improvise-Adapt-Overcome

[david-bartlett]

I have a 1953 Evinrude 15102 which has 105 on both. It had 105 on bottom and 80 on top when I got it, but cleaning up the head and a new head gasket evened it up nicely.

[fisherman6]

My ’54 SuperFastwin 15012 has 87 on the bottom and 89 on top. It has a lot of hours on it but it’s a nice runner.
-Ben

OldJohnnyRude on YouTube

[Pete]

For service engines lower than about 80 starting becomes a problem but once running it will do OK. Anything above 100 is generally good.

[Author]

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