1957 35HP Big Twin

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bigballerg

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Did a fuel pump conversion that worked successfully took for spin etc.... Worked at idle for the 1st time ever and also cruised WOT for 20 min around lake back and forth WOT to idle etc... worked like a CHAMP!
THEN.... Boat sat for about 2 weeks when I went to start it would not turnover. Battery full charged. Cranks, cranks, cranks but will not go, UNLESS I pull a spark plug and spit some gas in there, replace spark plug then try and turns over... runs great.. after its on for a few I kill it. If I try to start up again, it works perfectly. If I wait a couple days, i'm back to cranking and removing spark plug etc.... NOW, I did take for a spin and idle worked great BUT at WOT it worked great for 30 seconds then slowly started to fade to eventually the motor seemed to be PULSATING (Wanting to go but wanting to die and getting me sea sick in the process) then eventually dying.... It would start right up after this incident at WOT. I repeated adjusting the high speed needle, but at WOT eventually died... Not flooding because I could turn over instantly... more like starving for fuel or SUCTION??
 
HighTrim

HighTrim

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Re: 1957 35HP Big Twin

How did you do the conversion? Which pump did you use?

Did the carb get cleaned/rebuilt at the same time, with new fuel lines and clamps?

Vent open and not clogged on tank? No air leaks?
 
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bigballerg

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Re: 1957 35HP Big Twin

I 1st rebuilt carb., then worked fine... then Pressure tank was leaking gas etc.. so did conversion and engine worked great that entire time. Until recently since sitting for a couple weeks
 
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bigballerg

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Re: 1957 35HP Big Twin

As far as fuel lines etc.. all new with new tank and hoses. tank is one that vents on the cap (i think) when tightened to the point of hearing the clicking sound. Worked great the 1st couple trips that lasted about 45 min or so on lake...
 
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F_R

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Re: 1957 35HP Big Twin

Let's get back to the basics. Did you check the coils? Did you even look at them? Your story smacks of the symptoms of old cracked OMC coils. ALL 1957 OMC motors have bad coils unless they have already been replaced. You are wasting your time till you deal with them.
 
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bigballerg

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Re: 1957 35HP Big Twin

im sure they are old... BUT I have a question for you... the only difference between when was running like a champ and not was when I put fuel in tank. I put A LOT meaning to the rim of the cap. Would that keep from creating the proper vacuum or suction from occurring?
 
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bigballerg

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Re: 1957 35HP Big Twin

Lets talk Coils, would that keep it from starting after I get it going by removing spark plug, etc.. as described above in original post? It starts up fine after I get it going?
 
nwcove

nwcove

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Re: 1957 35HP Big Twin

bigballerg said:
Lets talk Coils, would that keep it from starting after I get it going by removing spark plug, etc.. as described above in original post? It starts up fine after I get it going?
Click to expand...

you say you're sure the coils are old? if they are old, there is a %100 failure rate on them, and they will create some odd symptoms. you really need to have a look and see if they are the originals.
as far as the tank goes, if its one of the newer style epa approved tanks, there are a few threads about guys having to drill a hole in the cap. ( i personally dont endorse that option!)
 
HighTrim

HighTrim

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Re: 1957 35HP Big Twin

Faulty coils will fail sporatically, and as Frank stated, the motor will be impossbile to tune without dealing with that issue first. Pull the inspection window on the flywheel and have a looksee.
 
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bigballerg

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Re: 1957 35HP Big Twin

inspection window?? Is that easy to do? Do I need harmonic puller to do that?
 
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HighTrim

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Re: 1957 35HP Big Twin

Very easy. 3 screws, no need to pull the flywheel to just see.

Pull the recoil, then there will be an oval plate screwed to the flywheel. Take that off, remove the plugs, then you can turn the flywheel easily clockwise to see the whole ignition system.
 
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bigballerg

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Re: 1957 35HP Big Twin

I'm going to be looking at coils today to see their conditions.... I thought of something last night that makes me wonder if this is the problem. When I was done testing at the lake and bringing in the boat. I could not KILL the engine when pressing the "Choke" button. I know the button "ELECTRICALLY" works as when I press down it clicks and moves a lever into the Solenoid? Then I thought of my problems.. I could only cold start engine by taking out spark plug, spitting fuel in there etc... from that point on I could start the boat all day long. BUT at WOT it seemed to be starved for fuel.... When trying to cold start using choke it seemed like there was no effect if I pressed button or not. Could the solenoid have something to do with this being STUCK open or closed and hence the reason I can't get it started when cold and bogs down at WOT?
 
HighTrim

HighTrim

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Re: 1957 35HP Big Twin

You are killing the motor by choking it. Also used for cold starts. So possibly the choke solenoid is faulty. Try manually choking it and see if that helps it start.

You are choking it on cold starts right???
 
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bigballerg

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Re: 1957 35HP Big Twin

Yes, choking it at cold. Tried MANUALLY Choking and no effect.... Motor at crank sounds strong and great but just wont turn over..
 
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bigballerg

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Re: 1957 35HP Big Twin

UPDATE, I went back to needles and started from scratch bottom and top settings etc... Sucker turned on and started running. I cant though CHOKE it out. I press button and manually try as well and it keeps going UNTIL I screw in the low speed all the way in and then finally stops. What would cause it not to choke out?
 
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bigballerg

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Re: 1957 35HP Big Twin

After playing with the low speed needle, I was able to get it at a point where I was able to choke it out using the choke button. I guess a lesson learned for me is these needles even though I have them pretty tight so vibration wont move them around, they obviously do. I thought I had them all dialed in and never had to adjust them again but from now on will check the settings if I am having starting issues. Haven't tested WOT in water yet, but hopefully will all work out like it did before... Thanks for all the feedback and thoughts!!
 
HighTrim

HighTrim

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Re: 1957 35HP Big Twin

Do you have adequate quality/quantity of packing washers behind the packing nuts?
 
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