Force Timing Advance

[Sugo]

I purchased a used 1996 120hp force outboard. After 6 months of use It started running very rough. I found it to be a blown head gasket. After replacing the head gasket it ran perfect except for the fact that the idle was now increased to 1100 rpm. After ruling out control linkage and carb adjustment, I was able to achieve a good idle around 650-700 by adjusting the timing advance linkage. This had not been adjusted since I owned the motor. Could this linkage have been adjusted to compensate for a leaky head gasket prior to me owning the motor. Would timing adjustment be affected by a head gasket issue ? Could someone share some insight to this concept. It works great now but I am the kind of person who needs to understand why. Thanks for any education on this matter.

 

[jerryjerry05]

Re: Force Timing Advance

The timing linkage shouldn't make a difference.
You shouldn't try to adjust the idle there.
It can cost you a powerhead.
The difference could be? The low comp on 1/2 cylinders could make it idle lower.
Then the motor has good comp and it's running like it should bringing up the idle.
The idle should be about 750-800 in gear.
The idle in N should be about 1100=1200.
Re-time it and reset the idle.
The idle is adjusted with the towershaft not the timing linkage.
Like I said it can cost you a powerhead if your timing is off.

 

[Sugo]

Re: Force Timing Advance

Thanks for the info. That makes sense. At 1100 rpm it bangs into gear a bit hard and it always shifted smoothly (while the compression was compromised) prior to the head gasket repair. Is the hard shifting avoidable? or will it not cause damage? I am uncertain what you mean by the tower shaft. Where is the idle adjustment you mentioned ? Thanks again

 

[Jiggz]

Re: Force Timing Advance

The tower shaft is where the two linkages for the carbs connects to, which also controls the timing everytime the throttles are opened. At the very bottom of this tower is a screw labeled, idle. This is where you adjust idle rpm's.