1969 120 Merc valve adjustment procedure?

[arnoldclan]

I recently replaced the valve seals on my early 120 merc and its been a long time since I dealt with the valves, and my manual disappeared years ago with the guy that borrowed it, at any rate, with the hydraulic lifters, there seems to be only one nut to adjust on the rocker? What is the best way to adjust it? Any help would be greatly appreciated..

 

[dan t.]

Re: 1969 120 Merc valve adjustment procedure?

Start it up, back off the valve until it rattles, slowly tighten until it is quiet, this is 0 lash. Now you can do 2 things, 1 tighten 3/4 of a turn, go to the next valve OR, set all to 0 lash shut it off and tighten all 3/4 of a turn,wait 5 minutes for the lifters to bleed down, yer done. The second method isnt near as messy as the motor is only running a short time with the cover off.

 

[Don S]

Re: 1969 120 Merc valve adjustment procedure?

If you want to do it with the engine not running, do it like this.

View attachment Valve adjust 4 cyl GM.pdf

 

[Silvertip]

Re: 1969 120 Merc valve adjustment procedure?

If you wish to do this with the engine running, use heavy duty aluminum foil and wrap a piece around the push rod end fo each rocker arm. That keeps the oil from spurting all over. Still a bit messy but not as bad as using no protection. (That didn't come out just right!!!!)

 

[arnoldclan]

Re: 1969 120 Merc valve adjustment procedure?

Thanks for all your input. I really appreciate you sharing your time and experience...