Big Twin Hi/Lo speed needle fix

[ryendube]

Last year spent alot of time here digging up info on my 57 35hp evinrude. It has been plagued with the ever wandering hi/lo speed adjustment knobs.
This happened because the nut that squishes the packing to hold them firm would back out due to the threads being worn on a 50 year old plus carb

End of last season I took a look at it thinking about heli coiling it then it struck me drill the side, tap it and put a set screw in it. I used a #8 1/4 set screw on both and it has been working MINT all summer. Anyways thought I would share cause I remember a few having the same issue.

 

[Chinewalker]

Re: Big Twin Hi/Lo speed needle fix

I've never had one where the threads stripped out. I have had them where the packing was no longer packing and needed to be replaced. New packing adds friction to the nut, in addition to the needle valve, and holds everything from moving...

 

[ryendube]

Re: Big Twin Hi/Lo speed needle fix

I've never had one where the threads stripped out. I have had them where the packing was no longer packing and needed to be replaced. New packing adds friction to the nut, in addition to the needle valve, and holds everything from moving...

Well aren't you lucky, mine were.

hmm guess I should add I replaced the packing probably 3-4 times in one summer trying to fix it.

 

[jay_merrill]

Re: Big Twin Hi/Lo speed needle fix

Although I have never done it, I'd take a stab at trying a carb off of a later model 33hp OMC, if you ever need to repalce your carb and can't find one off of a '57 or '58. It should "bolt up" without modification and I doubt you would notice any performance difference at all.

BTW, I have a pair of '58 Bigtwins with original carbs, but I took the air silencers off of them, so I could mount a couple of Mercury starter solenoids (they're smaller than OMC solenoids) in the pans. When I did this, I mounted a couple of the white, plastic "carb covers/grills" that I canibalized from a pair of Johnson 33hp carbs that I had kicking around. They mounted without modification. The only difference that I can remember now, is that you have a long HS needle sticking through the bottom hole, instead of the stubby one that has a connection to a lever, as on the later motor.

With the metal covers and no silecer, the motors are pretty loud, but they run fine.



???

 

[F_R]

Re: Big Twin Hi/Lo speed needle fix

ryendube, thanks for sharing. It may be unorthodox, but if it worked, that's great. Creative engineering, that's what it is.