'73 merc 850 won't hold WOT

[linckeil]

I got my '73 850 on the water for the first time last weekend. it ran great, but would not stay at wide open throttle unless i physically held the throttle control all the way down. when held all the way down, it reved to 5100 rpm. when i let it go, it would back down to about 3000 rpm.

i haven't had a chance to look into it, but i'm wondering if this is corrected at the controls, or at the motor. i'd imagine there may be some sort of friction plate which can be tightened which will hold the lever all the way down on its own. or maybe there is no adjustment and i need to replace parts in the control box that have worn over the past 35 years.

other than this annoying problem, the engine ran great. any input is appreciated. thanks.

 

[Chris1956]

Re: '73 merc 850 won't hold WOT

The only way I can think of to increase the friction is to tighten the 9/16" bolt on the arm that runs from the throttle cable to the distributor. You will find the bolt on the port side of the motor, about 1/2 way up. There is no adjustment in the control box.

 

[linckeil]

Re: '73 merc 850 won't hold WOT

thanks chris. i'll give that a try.
if anyone else has an other ideas i'm all ears.

 

[StriperLover]

Re: '73 merc 850 won't hold WOT

i have the same motor on a 16 foot aluminum and i am having some issues with it my question is what size boat you have and what prop are you using to get 5100 rpm and at what speed are you getting at wot.

thanks Billy

 

[linckeil]

Re: '73 merc 850 won't hold WOT

i am using a 17 pitch 3 blade aluminum prop. it has very good pickup out of the hole. its perfect for my setup. at WOT it hits 5100-5200 rpm and tops out at 30 mph dead on. the boat is a '73 18 foot searay. its a heavy boat for it's size. its rated for a 150hp motor and i'd actually like to find a 1500 inline 6 merc from that era. anyone in or around CT got one???