1996 150 HP Offshore V-6 Timing

[MaggieRose]

Started my engine after rebuilding it over the winter.

I completed all link and synch checks and, with the white/black idle stablizer lead isolated, found the idle timing at 8.5 degrees ATDC. The idle speed of this engine sounds smoother than I have ever heard it in the last 6 years.

I have read on this site, that because of the 10% methenol in gasoline, an additional 2 degrees of retard is recommended beyond the Mercury timing specs.

I am setting up to check the cranking and WOT timing, but the shop manual has a caution that "the maximum timing at cranking speed in neutral to be retarded 3 degrees from specification." My carberated engine has specs of: 0-9 degrees ATDC IDLE, 21 degrees BTDC CRANKING and 19 degrees BTDC WOT.

With the W/B idle stabilizer lead isolated, what should the timing be for CRANKING and WOT on this engine?


HELP!!!

 

[j_martin]

Re: 1996 150 HP Offshore V-6 Timing

Don't worry about the idle setting. It gets you in the ball park and you change it to set your idle speed when you put it in the lake.

Wot timing can run about 23 - 25 degrees on that engine. The "advance" module is supposed to advance the timing 4 degrees at 5000 rpm, which is why you set the WOT timing at 19 degrees at cranking speed. If you plan to discard that module, (recommended) set your timing at 23 degrees. If you plan to run a lot at mid throttle and not WOT, then the timing module (if it works) helps smooth out the engine and prevent trouble.

That engine was built for ethanol in the fuel. What may cause a need for retarded timing is lower octane, or carbon buildup in the engine causing pre-ignition. With stock jetting, as long as the octane meets the minimum requirements, timing is not an issue.

If it were mine, I'd run it fast with non-oxygenated fuel, and lean it out a bit for performance, but that's me. The point is that the stock setup is fat enough for the fuel at the pump.

hope it helps
John

 

[MaggieRose]

Re: 1996 150 HP Offshore V-6 Timing

Thanks, John.
Hope to get the boat in the water soon. I will verify performance at the top end after I get some hours of break in on my new rings,