Mercury 150 EFI Timing Questions

[Tennessee T]

I have removed the idle stabilizer module from my 1997 Mercury 150 EFI engine, serial number 0G478627. I left the Idle Stabilizer Shift Kit installed. In going through the required sync & link procedure, my Mercury service manual says that the idle speed/pick up timing should be set to 0-9 degrees ATDC. The manual also says that the maximum timing at cranking speed should be retarded 3 degrees (for models equipped with idle stabilizer shift kit) from the specified 20 degrees BTDC, resulting in a 17 degree BTDC setting. My questions are:

1. 0-9 degrees ATDC is a wide range for the idle speed timing setting. Is there a specific setting that works best?
2. Is there a different and more preferred setting for the maximum timing, or should I stick with the manual's specification of 17 degrees BTDC?
3. I understand and am comfortable with checking the timing at idle speed with the engine running, but I am not comfortable with checking the setting for maximum timing with the engine running, at approximately 2,500 RPM. How does one safely perform the maximum timing/engine running step?

Thanks in advance for your advice!

[Rip Bass]

On question 3, I’ve never tested high speed timing but I’ve watched it done several times. The shop,I used to use had a test tank with a boat ramp at one end. They would put a test prop on,back down the ramp with the boat still strapped onto the trailer,then rev the engine to whatever rpm they needed. The test prop they used was an old aluminum prop with the blades cut off about half way down. You could do the same thing on a boat ramp. The test prop would allow the engine to reach top rpm while stationary,the normal prop won’t reach top rpm.

[leonreno]

I believe that with stabalizer removed, and cylinder indexed to TDC you should set timing to 23 deg btdc. Here is good answer for you on another thread:
http://www.bbcboards.net/showthread....balizer+timing

[JOE54]

remember 9 is leaner than 0 some boats need richer idle than others to accellerate out the hoe , i like to run um lean as possible but not bog mtr just runs cleaner/smoother low end try 6-8 to start gotta makr sure pointer is indexed first for accuracy ,wouldnt go over 23 , that mtr shouldnt have adv module , manual should have way to static timming max spark advance

[Tennessee T]

Thanks for your replies guys. JOE54, I have a question regarding your reply. You are correct, the manual does have a procedure to set static maximum timing. The part that I'm not comfortable with is, several steps later in the sync and link process, the manual instructs to, I'm assuming, double check the maximum timing adjustment that was set statically, with the engine running, in gear, in the water, "advance throttle arm until maximum spark adjustment screw contacts spark stop, at about 2,500 RPM." My question is how do you safely throttle the engine to approximately 2,500 RPM to check the maximum spark adjustment. Even with the boat backed down a launching ramp just far enough to get the engine adequately submerged in water, and the boat remaining strapped to the trailer, I just am not comfortable with doing that. Do I just have to put on my big boy pants and follow this procedure as outlined in the manual, or is there a safer way? A test prop, as Rip Bass suggested earlier, is not feasible for me, and furthermore, I wonder if the settings that I would set with a test prop would be applicable and optimum for my "everyday" prop.

[JOE54]

2500 rpm should be easily done with your prop on ramp get a helper or just use throttle arm with cable disconnected since you dont have advance module timming shouild be dead on done this way other mtr need to be checked running because of adv modules also, just back it in enough to sub merge cav plate for w/p