AQ170B timing marks

[Jimbangun]

Thank you for the amazing technical posts on this forum!
I am trying to adjust ignition timing on my AQ170B but the timing marks don't have any numbers on them. Can anyone help, please?

Pictures of the marks (when the engine was out of the boat recently) attached. Ignore the white marks, I made those so it wasn't from previous owner.

 

[aimlow]

IF the engine spins clockwise, when viewed from the front, the mark on the right MAY be tdc. Check TDC with a piston stop.

Measure the circumference of the damper, and divide by 360. That number is degrees/distance. For instance, 36 degrees is 1/10 of the distance around the damper.

 

[Jimbangun]

What I noticed is that at idle if I put the marker on the left mark, when I go to 2000rpm the marker would now point close to the right mark. The right mark is the one with the horizontal white line.

 

[Jimbangun]

IF the engine spins clockwise, when viewed from the front, the mark on the right MAY be tdc. Check TDC with a piston stop.

Measure the circumference of the damper, and divide by 360. That number is degrees/distance. For instance, 36 degrees is 1/10 of the distance around the damper.

Thanks for this. I just measured the angle between the 2 marks and it is 25 deg. Looks like the left mark is 0, then there are short marks for every 10 deg and a long one at 25 deg. The manual says set at 2,000rpm to 25-27 deg. So I just need to set to the right mark at that rpm.