Prestolite static timing help needed.

[brandonv]

1990 L Drive 120hp.

Cylinder #1 at TDC. Single hash mark on flywheel lines up with hash mark on the motor. Woohoo!

Now on to timing.... I removed the throttle cable and checked it:

-At idle the single hash mark on the flywheel lines up with the hash mark on the motor. Is this correct? Should the 2 marks be perfectly aligned?

-At WOT the furthest right hash mark (there are 3 of them 28, 30 and 32deg I assume!?!?) lines up with the hash mark on the motor. Does this mean I'm at 32 deg?

The manual I have doesn't state what the hash marks on the flywheel represent.

Thanks!

 

[Frank Acampora]

Re: Prestolite static timing help needed.

Idle timing is set as a starting point. Once the wide open throttle timing is set, idle timing may change by a couple of degrees--usually advanced. Note that as you set the idle speed with the stop screw, it moves the timing tower so both carbs and timing change. Thus, when finished setting the engine timing and idle speed, timing at idle may or may not be at 0 deg.

The center mark on the flywheel rim is usually longer and represents 30 degrees. The mark to the right of it ( since the engine turns clockwise) would be retarded 2 degrees or 28 degrees before top dead center. The mark to the left would be 32 deg. BTDC. 28 won't hurt you but performance may suffer a little bit--factory recommended setting at 30 deg. BTDC.

In your case, assuming the idle speed is correct, if you reset the WOT to 30deg.BTDC, the idle timing will also advance 2 deg. and the idle speed may be a little bit higher, necessitating turning the stop screw out a bit to bring the idle back down to 700-750 RPM in forward gear in the water.

Just remembered: If you set the WOT timing by cranking the engine without starting it, then when the engine starts and runs, magnetic force on the trigger assembly changes the timing when running. I don't remember which direction so if this is how you set the timing, then you need to check it while running at WOT.

 

[brandonv]

Re: Prestolite static timing help needed.

Many thanks!
Great write up.