Trying to bring a 1977 Johnson 70HP back to life

egclassic

Petty Officer 2nd Class
Joined
Dec 13, 2009
Messages
128
I just picked up this motor last week.
First thing I did when I got it home was to see if I could get it started, before I drop some money into it.
It fired up right away.
I ordered 3 carb rebuild kits w/floats, water pump kit, gearcase lube, new t-stat, spark plugs and fuel pump repair kit.
I soaked all 3 carbs in cleaner, and blew them out with compressed air. Rebuilt the carbs, paying close attention to proper float adjustments. Replaced all other parts listed.
Today I tried running in a barrel. It starts up fine, but does not seem to want to idle very well. also, seems like I have gas leaking from the carb opening(s). I have not done the "link & sync" yet.
I did mix two gallons of fuel and oil, with most of a can of seafoam. While running I sprayed the remaining seafoam into the carbs. At first, it would only run for a couple seconds and die. It did eventually run progressively longer but I had to keep working the throttle, then it got dark on me. I checked compression and had 120 across the board.
Am I correct in assuming these carbs have no adjustments? What about the fuel spilling from the carbs?
Thanks in advance.
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: Trying to bring a 1977 Johnson 70HP back to life

You are correct, there is no adjustment on your carbs.
When you overhauled the carbs did you remove the core plugs on top of the carbs and clean the passages in there?
With that much sea foam in 2 gallons of gas it might not want to idle very well, might try mixing some fresh fuel with a 50:1 ratio and see if it runs better at idle.
Usually if you have fuel running out of the carbs, the float level is the problem.
 

egclassic

Petty Officer 2nd Class
Joined
Dec 13, 2009
Messages
128
Re: Trying to bring a 1977 Johnson 70HP back to life

Thanks for the reply.
No I did not remove the core plugs, figured I'd be opening a can of worms!
I did add two more gallons of fresh mixed fuel to the tank today and ran it again. It definately improved, but still stumbled a little. I then did "most" of the link 'n sync procedure (not the timing part yet) and now she idles perfectly.
The seafoam cleared alot of crud out of there.
I may try to pull the carbs and re-check the float adjustments again, the only time fuel comes out of the carbs now is when its cold and I have to choke it, not while its running. The stand I built is straight up and down and the motor leans forward, I was hoping maybe that contributed to the fuel spillage, but it is not leaning forward anymore than if you had it trimmed/tilted on the boat.
 
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