1987 35 hp cannot get idle below 1200

[tstokka]

1987 Mercury
35 HP s/n 0B189033


I've been working on this motor for a while. I've gone through the carb, fuel pump, and electrical. I cannot get the idle lower, so i tried getting initial timing set.

I pulled the plugs, and attached spark testers.
then hooked up my timing light.
cranked the motor over and found that initial timing is 5 ATDC

there is a label on the front that says it should be 3 BTDC

I'm thinking the previous owner monkeyed with the screws that limit this and I don't know which ones to adjust. attached are some pictures of the 4 different set screws.






I've looked at a lot of manuals online, and cannot find the one that has anything like this in them. I'd like to know how to get the timing set right. Also if possible finding a manual for the thing.

any help would be greatly appreciated.

thank you,

tony

 

[tstokka]

Re: 1987 35 hp cannot get idle below 1200

anyone have this type of set up?

 

[jslu]

Re: 1987 35 hp cannot get idle below 1200

I have the exact same engine.
Ref your pic of adj screws. Should be set up in this order:
Middle screw is for initial timing: Should be set for 3 degrees BTDC at cranking speed
Upper right hand screw is max timing advance: I set mine at 21 degrees BTDC, Merc manual says 27 degrees.
Lower right hand screw is WOT adjust screw: Adjust till carb shutter is parallel to throat. You want the adj screw to stop the shutter to this position, not the carb itself.
Lower left hand screw is idle adjust: Merc manual says adj to 800 RPM in neutral. My old 87 Merc will not go reliably below 950-1000 RPM.
I will send Lync and Sync procedure in another thread.

 

[jslu]

Re: 1987 35 hp cannot get idle below 1200

In the I boats forum search block, type in, Mercury timing
Next look for thread "Mercury 80 HP timing, dated aug 24 2011.
Read thread response #5. I used this procedure to to initially get my Merc back to normal adjustments. It closely follows the Merc manual which I have recently purchased.
Good luck