1950's Fleetwin Fisherman Challenge!

[BilgeMonkee]

First post here - in an attempt to help my brother-in-law through the loss of his father (he was also my best friend) I thought it would be nice to get his fathers old Fleetwin running for him. Seemed simple at the time? When I finally got the Fleetwin in the shop I discovered the low end was unsalvageable. As luck would have it I spotted a similar looking motor at a yard sale thinking I could swap out some parts? The second outboard turned out to be a Fisherman.
When I got the Fisherman in the shop I realized the difference (the Yachtwin has larger CC and hence more HP), but they looked like they shared the same power head/lower unit interface?

So I dove in and put the nice clean Fleetwin power head onto the lower unit of the Fisherman. All seems to be ok there with nice new gaskets.

Put the water to it and pulled the cord.... after much sputtering and coughing I discovered I could not run it up to speed - I realized there was more going on here. Pulled the plugs; the lower one looked oily with gas but the top looked dry as a bone? What gives here?!? The compression feels really good/crisp when I pull the cord. The power head appears to be in excellent condition. I pulled the carb and it looked very clean but I super cleaned it anyway. Spark shows crisp on both cylinders.

Also - the old twin fuel/air lines tank system? The pump seems poor on that. Should I abandon that system and go with a single line?

Thanks in advance for any help here.... I have so much time in this project and really dont want to give up now!

 

[racerone]

Actually the pressure tanks work well and are very reliable.----You pump fuel into the carburetor.----When motor start it quickly pump crankcase compression into the tank to keep fuel flowing into the carburetor.----Repair kits and parts are available.

 

[BilgeMonkee]

That helps to know that. Thank you very much.

 

[oldboat1]

Fleetwin is a 7 1/2, Fisherman is a 5 1/2, Yachtwin can be a 9.9 or 8 (possibly a 6 as well -- not sure of that.)

 

[RCO]

Did you check or replace the carbon seal on the driveshaft? If that's leaking it won't pull a fuel charge into the bottom cylinder.

 

[racerone]

The bushing at the bottom of the block is a tight fit.------How much air can leak in a 600 RPM?-----During one twentieth of a second or less time ?

 

[BilgeMonkee]

Did you check or replace the carbon seal on the driveshaft? If that's leaking it won't pull a fuel charge into the bottom cylinder.

I did not know enough to check this when I reassembled the motor.

The bottom cylinder gets plenty of fuel (at least I can see a LOT of oily residue on the bottom plug). The top is dry as can be, as in it has no oil or gas on it at all. You mentioned that if the seal is bad on won't pull fuel into the BOTTOM cylinder. Do you think this still might be the problem? This motor coughs and sputters but it does not rev up at all.
Thanks for your help!

 

[racerone]

Sounds like it is running on just 1 cylinder.-----Remove top plug wire.----Does the motor start ?-----Now try and start it with just the top plug wire on.----Report what you find.----Compression test done , post the actual numbers.----I doubt a bad lower seal will stop the bottom cylinder !----The lower seal is there to prevent water from getting into the engine !

 

[BilgeMonkee]

Sounds like it is running on just 1 cylinder.-----Remove top plug wire.----Does the motor start ?-----Now try and start it with just the top plug wire on.----Report what you find.----Compression test done , post the actual numbers.----I doubt a bad lower seal will stop the bottom cylinder !----The lower seal is there to prevent water from getting into the engine !

I'll do this and write back. Thanks very much for the input.

 

[JDusza]

Cover the basics. If you suspect it running on one cylinder, pull one spark plug wire at a time and see what happens. If nothing then the cylinder isn't contributing. If there's a performance change then the cylinder is working.
Compression test, spark air gap test, verify spark plug, timing check, spray premix manually.
No?
J
p.s., pressurized tanks are cool