73' mercruiser 120 shift problem

[dieselmax]

I finally got my boat in the water and all is well except that when shifting from forward to neutral i have to go past neutral to get it out of gear same as going from reverse to neutral i have to go past neutral to get it into neutral i have adjusted the lower shift cable when i put it all together did i adjust it wrong or is there another adjustment to make also the boat is an 18' starcraft aluminum top speed is around 37 mph at 4000 rpm with a 21 pitch prop on choppy water is that ok or should i look for a smaller pitch ? boat is mainly for fishing


ps: thanks to all the great people here i couldn't have got this far without you i read this forum almost every night all winter long learning all that i needed to know to get my boat this far

 

[dieselmax]

Re: 73' mercruiser 120 shift problem

anybody?

 

[Badhen]

Re: 73' mercruiser 120 shift problem

could be the shift interrupter switch, are you familiar with it?

 

[dieselmax]

Re: 73' mercruiser 120 shift problem

thanks for the reply will look into it this weekend boat seems to shift fine from forward to neutral but still has issues from reverse to neutral brought it home from the lake today seems to run alright other than a few little kinks to iron out

 

[bigskiohio]

Re: 73' mercruiser 120 shift problem

rpms are what you go by on prop with your normal load i am not sure but you might be just about right or a little high if that is wot, i run a 19 pitch but my tach doen't work but it sounds good but i dont run it wide open to much 1973 ss 120.But i plan on trouble shooting my gauges this week.

 

[fishrdan]

Re: 73' mercruiser 120 shift problem

I'd check the shift interrupt switch as suggested, make sure it's momentarily cutting out the engine when shifting out of gear. You should be able to hear it when idling in gear and then shifting into neutral, N>F, F>N, N>R, R>N, etc..

When I adjusted the shift cables on my 73 140HP, I had to play with the adjustment a bit to get it perfectly dialed in,,, though I was using a POS Seloc manual at the time.

The boat's PO had a ton of drive work done on it before I bought it and the lower shift cable's anchor point (barrel nut) was very sloppy on the stud, like a 1/4" stud fitting in the barrel nut's 3/8" hole. (Don't laugh) I took a Bic pen, cut a chunk off it and used it as a bushing so the shift cable mounted on the stud properly. I don't know if there was a bushing missing or if the newer cable had a larger diameter hole in the barrel nut, but taking the slack out of the anchor point made all the difference in the world while making the shift cable adjustments. Bic pen bushing worked great for 10+ years,,, LOL