1961 Seahorse 5.5 Compression?

[61_Johnson]

I checked the compression on my motor today. Both cylinders read 55 PSI. I am assuming that since the numbers matched then I have no problems. Am I right or wrong, I can't find the recommended compression reading in my manual.

Thanks

 

[freddyray21]

Re: 1961 Seahorse 5.5 Compression?

55 is a bit low imo, but it will probably start and run with that. Do a decarb once you get it running then retest.

 

[61_Johnson]

Re: 1961 Seahorse 5.5 Compression?

It will start and run, just dies after about a minute. My next step is to replace the coils, that is the only part that hasn't been worked on!

I have rebuild the carb and lower unit.

Does anybody what the specified compression reading is supposed to be?

 

[jbjennings]

Re: 1961 Seahorse 5.5 Compression?

Just so you know, OMC NEVER put out any specific compression numbers. (I've asked and looked because I'm curious like you)
Your motor probably had about 85 or 90 lbs. brand new I suspect based on my quizzing of everyone knowledgeable I can find. A good 5.5 has about 75 or 80 lbs. I believe, but I'm no expert on 5.5's since I don't own one. I believe it will run fine with 65 lbs. and compression guages are notorious for being off a lot. If it idles good, don't worry about it. If it shuts off after a minute, compression isnt' your problem.
JBJ​