Max advance timing?

[huntin dawg]

Hello Gents,
If you saw my post a couple days ago about my 7.5 having intermittent miss at WOT I think I found the problem.
I performed the timing and syncronization procedure per my Merc shop manual and found that it was slightly out of adjustment. It was advancing too far.
Does that sound like a reason for it to skip/miss at WOT?

I'll know for sure this week when I get it back on the water but I figured a pro here would confirm or deny the significance of my findings.

Thanks,
HD

 

[sschefer]

Re: Max advance timing?

A miss or falling flat on it's face at WOT could definitely be too much advance. If it's like most Merc's all the timing should be in at about 3000 RPM.

Most 2 stroke Merc engines (non race) can handle a max of 25 degree's of BTDC timing. Since these are not blueprinted engines, dwell can often vary between cylinders so to be on the safe side I like to run them at about 23 degrees.

Set yours to what the Merc Shop Manual say's, it accounts for the possiblity of error.

 

[huntin dawg]

Re: Max advance timing?

My manual says to find TDC, rotate the flywheel counter-clockwise to .193 BTDC, and then adjust the max advance stop screw just to where the points open up. I did that. It only took about 1 1/2 turns of the screw so I guess it's right. I'll get it in the water this week to open it up and see.

Thanks,
HD

 

[sschefer]

Re: Max advance timing?

My manual says to find TDC, rotate the flywheel counter-clockwise to .193 BTDC, and then adjust the max advance stop screw just to where the points open up. I did that. It only took about 1 1/2 turns of the screw so I guess it's right. I'll get it in the water this week to open it up and see.

Thanks,
HD

If that what merc say's then sounds like you nailed it. Best of luck!

 

[huntin dawg]

Re: Max advance timing?

The "synchronization" procedure did the trick.

I took it to the lake today and ran it WOT for a few minutes. She ran smooth. Funny how a tiny bit of over advanced timing will give it the hicups.

HD