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1950 Evinrude Fleetwin 7.5hp 4434 Power Issues

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No1b4me

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I have been trying to restore my 1950 Evinrude Fleetwin 4434 that I inherited from my grandfather. I used this motor all the time when I was younger on a 12' v-bottom boat. It would move that boat along at a decent speed. The motor had sat in storage for about 12 years after my grandfather passed. I finally have the time to mess with it and would love to have it working like it did back then. When I first tried to start it there was no spark whatsoever so I tore into it to check the coils and points and noticed that the coils appeared to be melting away, they epoxy or whatever they are incased in had run down the sides all over the place. So I decided I was going to pull it all apart and replace anything that looked worn out or damaged. I ordered the service manual, found a new water pump impeller, seals for all the shafts and a carburetor rebuild kit for the tillotson MD 34b. When it came to the ignition I found that everything for the 1950 4434 were pretty much obsolete. So I got crafty and removed the stock coils from the laminates and replaced them with some Tecumseh coils I found online, I had to do some modifications but I got them to fit. Replaced the condensers with some condensers for a 70 chevelle and managed to find some new old stock breaker points. I got everything back together and to my surprise it started rite up. I have a little 14' v-bottom seanymph that I put it on and took it down to the river to give it a test spin. Got it in the water and started it up and went through the carb adjustment procedures outlined in the manual. It idles way better than it ever did when I was a kid but at WOT it just doesn't seem to have the power it once did. I brought it back home and have been tinkering with it for the past few days trying to find the issue with no luck.

Checked compression 80psi on both cylinders
Regular pump gas mixed 16:1 with Quicksilver Premium Marine 2-stroke oil
Points are gapped .20
Champion J4C plugs gapped at .30
Float level in the carb is adjusted 3/32 below rim of fuel bowl as instructed in the service manual
Checked the ability of the coils to jump a 1/4" air gap per manual instructions
And made sure the cam follower closes the butterfly when the armature base is in the stop position

I have triple checked everything and it all is as it should be as far as I can tell.

Do you think it might have something to do with the coils I used to replace the obsolete ones?
I was thinking I might try stepping up the heat range on the plugs to compensate for the coils, maybe they are not as powerful as the originals.
I have the j4c, j6c, j8c and j11c champion plugs but was concerned that stepping up the heat range could possibly burn a hole in the pistons.

Anyone have any thoughts or recommendations? Am I missing something obvious?
 
The coil mod must be working. But are you sure it is running on both cylinders? Any chance the spark is jumping to the flywheel or something? Just so you know, the original 580040 coils are available here at marineengine.

I wouldn't go hotter than the J8C plugs. But that isn't going to help anyway.

Finally, how does your weight compare now to when you were a kid?
 
I am not positive it was running on both cylinders while on the water, it was late in the day and I wanted to get it back on the trailer before it got dark. I verified that it is indeed running on both cylinders on the stand. Tore it down tonight and removed the flywheel to visibly inspect for any signs of spark jumping or components rubbing, and double checked point gaps. Everything looks ok.

I did not want to invest $220 for the original coils, I got 2 of the Tecumseh coils for a little less than $30 and they are readily available at the local part stores.

As far as weight goes I'm 50-60 pounds heavier than the last time I used it back in the day, but I had a wooden barrel full of concrete about the size of a metal milk can that I kept in the bow of the boat to keep the nose down when I was fishing alone.

I have some seafoam soaking in the cylinders now and plan to decarb it tomorrow, I don't believe that has ever been done. Ill bring back out on the river this weekend and see how it goes.

magneto 1.jpg
 
Did the decarb process today, there was a huge amount of crud in the barrel when it was done. Got it all back together and ready to test it out tomorrow, I hope it runs as good on the water as it does in the barrel.20471984_10211285878795162_215005990_n.jpg20535958_10211285879035168_1949341097_o.jpg
 
No1b4me said:
I have been trying to restore my 1950 Evinrude Fleetwin 4434 that I inherited from my grandfather. I used this motor all the time when I was younger on a 12' v-bottom boat. It would move that boat along at a decent speed. The motor had sat in storage for about 12 years after my grandfather passed. I finally have the time to mess with it and would love to have it working like it did back then. When I first tried to start it there was no spark whatsoever so I tore into it to check the coils and points and noticed that the coils appeared to be melting away, they epoxy or whatever they are incased in had run down the sides all over the place. So I decided I was going to pull it all apart and replace anything that looked worn out or damaged. I ordered the service manual, found a new water pump impeller, seals for all the shafts and a carburetor rebuild kit for the tillotson MD 34b. When it came to the ignition I found that everything for the 1950 4434 were pretty much obsolete. So I got crafty and removed the stock coils from the laminates and replaced them with some Tecumseh coils I found online, I had to do some modifications but I got them to fit. Replaced the condensers with some condensers for a 70 chevelle and managed to find some new old stock breaker points. I got everything back together and to my surprise it started rite up. I have a little 14' v-bottom seanymph that I put it on and took it down to the river to give it a test spin. Got it in the water and started it up and went through the carb adjustment procedures outlined in the manual. It idles way better than it ever did when I was a kid but at WOT it just doesn't seem to have the power it once did. I brought it back home and have been tinkering with it for the past few days trying to find the issue with no luck.

Checked compression 80psi on both cylinders
Regular pump gas mixed 16:1 with Quicksilver Premium Marine 2-stroke oil
Points are gapped .20
Champion J4C plugs gapped at .30
Float level in the carb is adjusted 3/32 below rim of fuel bowl as instructed in the service manual
Checked the ability of the coils to jump a 1/4" air gap per manual instructions
And made sure the cam follower closes the butterfly when the armature base is in the stop position

I have triple checked everything and it all is as it should be as far as I can tell.

Do you think it might have something to do with the coils I used to replace the obsolete ones?
I was thinking I might try stepping up the heat range on the plugs to compensate for the coils, maybe they are not as powerful as the originals.
I have the j4c, j6c, j8c and j11c champion plugs but was concerned that stepping up the heat range could possibly burn a hole in the pistons.

Anyone have any thoughts or recommendations? Am I missing something obvious?
Click to expand...
Hello sir, if you're still alive and well hopefully you can help me out I have this same unit having a no spark condition.

Wondering if you're able to link me to the parts you used for replacement in your ignition system. The contactors, coils, condensers.

How'd yours turn out by the way? Thanks
 
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