does anybod know where to set the rubber stop on full spark timer advance

Joined
Jun 19, 2009
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15
i have 1974 johnson 70 want to know where to set the rubber stop on the full spark timer advance srew that is under flywheel
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: does anybod know where to set the rubber stop on full spark timer advance

Once someone tells you what the full spark advance setting is, adjust using the following method.

(Timing At Cranking Speed 4?)
(J. Reeves)

NOTE: If your engine has the "Fast Start" feature", you must disconnect/eliminate that feature in order to use the following method. The "Fast Start" automatically advances the spark electronically when the engine first starts, dropping it to normal when the engine reaches a certain temperture.

The full spark advance can be adjusted without have the engine running at near full throttle as follows.

To set the timing on that engine, have the s/plugs out, and have the throttle at full, set that timer base under the flywheel tight against the rubber stop on the end of the full spark timer advance stop screw (wire it against that stop if necessary).

Rig a spark tester and have the gap set to 7/16". Hook up the timing light to the #1 plug wire. Crank the engine over and set the spark advance to 4? less than what the engine calls for.

I don't know the full spark advance setting your engine calls for, but to pick a figure, say your engine calls for 28?, set the timing at 24?. The reasoning for the 4? difference is that when the engine is actually running, due to the nature of the solid state ignition componets, the engine gains the extra 4?.

If you set the engine to its true setting at cranking speed, when running it will advance beyond its limit by 4? which will set up pre-ignition causing guaranteed piston damage! You don't want that to take place.

No need to be concerned about the idle timing as that will take care of itself. The main concern is the full advance setting.

Be sure to use your own engines spark advance settings, not the one I picked out of the air here in my notes.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: does anybod know where to set the rubber stop on full spark timer advance

I found the full throttle spark advance listed in SB#2004 for the 1974 70HP was 28? with throttle pickup of 4?.

See OMC Service Bulletin # 2004 dated July 1980, page 2.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: does anybod know where to set the rubber stop on full spark timer advance

Good man zeke.
 
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