1955 Evinrude Fleetwin 7.5hp carb kit?

[fleetwinner]

Hello, I recently purchased my first antique boat motor, a '55 fleetwin, for more than I'd like to admit. The previous owner took great care of it in that every part has semi-recent grease and all the rubber parts were less than a few years old. I've already gone about changing the gear oil and impeller, and have had the engine running, peeing, shifting (sometimes), and propelling both directions in a bucket, but the engine cut on the shift during the on-water test, then wouldn't crank again. The prop isn't locked and it still shifts most of the time, and most signs are pointing to the carburetor, which I should've rebuilt from the getgo. This brings me to my main question, which is what carburetor rebuild kit to use for this particular model? I've found some advice on youtube but wanted to confirm with the people. Thanks for any help/advice

 

[racerone]

Post the actual compression values here.-----And does spark jump a gap of at least 1/4" on both leads ?----It should shift each time !----Investigate that BEFORE spending more beer tokens on this motor

 

[fleetwinner]

Haven’t tested spark plugs but there is definitely power on time to each plug, planning on spending the $6 to replace them anyway. Sometimes the shift knob will just not go into gear, moving a little and springing back to neutral, but most of the time shifts just fine.

 

[racerone]

Model # of your motor is ?-------The question is---Does spark jump a gap of 1/4"?----That has nothing to do with the sparkplug !

 

[fleetwinner]

Model number 7518. Spark test is next thing on my list

 

[fleetwinner]

Model # of your motor is ?-------The question is---Does spark jump a gap of 1/4"?----That has nothing to do with the sparkplug !

Forgive my rookie knowledge but why doesn't that have anything to do with the plug? Also, any recommendations on a carb maintenance kit?

 

[racerone]

You do a maximum spark intensity test with a test device.----Store bought $10 or home made with cardboard , glue and wire.

 

[fleetwinner]

You do a maximum spark intensity test with a test device.----Store bought $10 or home made with cardboard , glue and wire.

Adjustable gap spark tester acquired, waiting on sunset and a buddy to be able to see if it's jumping the 1/4" gap.

Will a compression test tell me anything other than whether or not to scrap the thing? I believe the values either match in the acceptable range or they don't, and you're pretty much screwed if they don't. The compression seems even and strong so I don't see it as necessary unless it can provide some other insight.

As for the shifting, ??? I can't begin to understand why sometimes it clicks into gear just fine and sometimes the shifter won't move out of neutral position, seemingly at random. It hasn't done this while running but I'm sure it will.

Thanks again for imparting any knowledge you can onto this rookie

 

[racerone]

Propeller must be turning when shifting motor on a stand.

 

[Nordin]

Fleetwinner the compression numbers are also important.
These small engines should be in range 80-120 PSI maybe higher, but most important is that the numbers are close to each other.
Not more different than 10-15% is a general rule.
They will run with 80PSI but 100PSI or more is preferable.
Follow racerones advise he knows the OMC stuff.

 

[fleetwinner]

Propeller must be turning when shifting motor on a stand.

Prop turns correctly in all gears when it will get into them, free in neutral and locked in drive and reverse. It's just that sometimes the shift handle will not click into gear. Spark test complete, easily jumped a gap of 1/4" on both leads. Compression test is getting rented today

 

[fleetwinner]

Fleetwinner the compression numbers are also important.
These small engines should be in range 80-120 PSI maybe higher, but most important is that the numbers are close to each other.
Not more different than 10-15% is a general rule.
They will run with 80PSI but 100PSI or more is preferable.
Follow racerones advise he knows the OMC stuff.

Those are the numbers I had in mind, but my question is what does it tell me if there's too much deviation or they are underpressurized? Thanks

 

[racerone]

When shifting on a stand you must turn the propeller when operating the shift handle.

 

[tphoyt]

I think of compression as if it’s blood pressure. It’s the first thing they check when you go to the doctor to determine your over all health. If it’s off everything else will be as well.

 

[racerone]

These early 7.5 HP motors have a poorly designed head gasket.--No metal ring.-----A wise owner would do a compression test !

 

[fleetwinner]

These early 7.5 HP motors have a poorly designed head gasket.--No metal ring.-----A wise owner would do a compression test !

I think of compression as if it’s blood pressure. It’s the first thing they check when you go to the doctor to determine your over all health. If it’s off everything else will be as well.

Thanks for the info, I'll do the test today. Still thinking the carburetor needs to be cleaned out or rebuilt and am struggling to find a trustworthy seal/gasket/jet kit. Should I replace the head gasket? The other gaskets I've come across were all in good condition though I plan to replace them anyway.

 

[fleetwinner]

These early 7.5 HP motors have a poorly designed head gasket.--No metal ring.-----A wise owner would do a compression test !

Compression values 80psi on the dot for both cylinders. I know I should be aiming for 90, but it seems to be good enough that it wouldn't cause my problem. Spark also jumped the 1/4" gap on both leads, carb rebuild next?