slow speed adjustment knob too big or needle valve too small

[RTripp]

I ordered the correct slow speed adjustment know from a diagram of 1988 15 hp johnson and it is not able to grab the needle valve. I'm thinking someone who owned this before me might have put the wrong needle valve in the carb.

The needle valve seems to work ok. But, I have to take the cawling off to make an adjustment. I see the needle valves cost $50-60, so....would a needle valve with the right size end piece, which the slow speed adjustment knob attaches to, make a difference with the performance of the carb?

 

[F_R]

Did somebody mutilate it with a pair of pliers or something? The needle valve is more or less a set-it-and-forget-it item. Once set, only a minor tweak for major changes in temperature or altitude is the norm. As for me, I think for 50 bucks, I could put up with it.

 

[kbait]

I believe that one has the plastic carb top. They often cracked and needed replacing. Some models had replacement carb tops that cost over $80 - if memory serves. A slightly newer replacement fit/worked fine (about $14), but the needle sat deeper, and knob didn’t quite grab it. I removed the rubber grommet behind the knob, and then knob clicked onto needle (barely).. perhaps that is what happened.

 

[oldboat1]

sure the plastic knob isn't broken/stripped?

 

[RTripp]

when I bought it the plastic knob it came with was too big, didn't do anything. So, I bought a new one and it is the same as the one that came with it. The carb is all metal. There are grooves on the end of the needle, so that part hasn't been stripped. It just seems like maybe the guy I bought it from, supposedly a mechanic, might have put in a different sized needle valve.

The new knob isn't stripped. It's just too big to grip. here is a picture of it http://www.crowleymarine.com/parts/13061.cfm
There are slots at the end which attaches to the needle valve but they just spin they don't grip on the ridges of the needle.