Timing light question

[mercuryman48]

Is there a special timing light thats used on outboards?..ive tried using my automotive timing light on my merc 850 and although the strobe light can be seen on the hand gun i cant get any reading on the flywheel markings to compare with the distributor timing pointer . Im pretty fair with mercruisers and this outboard is driving me crazy ..lol...thanks guys

 

[Chris1956]

Re: Timing light question

The timing lights used on OB are standard automotive ones.

Number one cylinder on that OB is the top one. Take out the plugs, and set #1 to TDC using a screwdriver. Note where the timing pointer or timing mark on the cowling (depends on year) is in relation to the flywheel. If the timing marks are way off, and you have a distributor, it is possible that someone installed the flywheel in the wrong position.

You will need a service manual to set the idle pickup and max timing advance on that motor.

 

[mercuryman48]

Re: Timing light question

Im all lost on my timing. My flywheel does not have any "straight line" mark on the top or sides of it . It Does have a timing scale on the vertical wall of the flywheel . My seloc manual only describes the procedure starting with aligining the straight line mark on the flywheel with the magneto pulley to be at TDC which i cannot do. So, after i find TDC using a screwdriver what do i i align with what get proper setting. Then, do i try and fire engine or go on and secondary throttle pickup and WOT lever adjustment first ....

 

[Chris1956]

Re: Timing light question

OK, The timing decal on the flywheel is where you check the timing with the light. Set #1 cylinder to TDC, using the screwdriver. Now see how close the TDC mark on the decal is to the timing pointer or cowling timing mark. if they are not close (within 1/4 ") the outer flywheel may be installed incorrectly. If so, loosen the 8 5/16 fine thread bolts around the flywheel nut and rotate the outer flywheel only until the timing marks align. The motor should still be a TDC for cylinder #1. Now reinstall the 8 bolts. Now remove the distributor pulley cover and see if the cast arrow points to the punch hole on the flywheel. It can be a 1/2 tooth off, which is normal. If not, remove the belt and turn the pulley until it is correct, and reinstall the belt. If you have the 850 with the timing pointer(likely a 1974 model), you should make sure it is exact. I would measure the distance from the spark plug seat on the head to the top of the piston (via the plug hole), add .464 inches and then turn the flywheel CCW until the piston is .464 inches lower in the cylinder. Now the timing pointer should be adjusted to indicate .464 BTDC on the timing decal. Follow the rest of the Seloc instructions to set the idle pickup timing and Max timing.