How do you set timing advance?

[vaughneric2000]

1978 Johnson 55HP 2-Cyl.<br /><br />I have been reading about how to set the timing advance in regard to the rubber stopper just below the flywheel. <br /><br />I have to admit, I'm having some sort of brain-lock on this. The timing marks in the flywheel are clear enough, and I know how to use a timing light to adjust engine timing. My Clymer manual gives 19 deg BTDC as the timing advance setting. <br /><br />But, and here's where I think I'm going to look stupid, but I'll ask any way, if I set cyl #1 to its exact timing mark arrow = TDC, what do I use to measure the timing-advance degrees on the movable timing advance.<br /><br />I am lost about this.<br /><br />Please help.

 

[Hooty]

Re: How do you set timing advance?

I'm not sure I understand your question but that's okay, we'll work it out.<br />First though, lemme ask why you're timing the engine? Has the timing been moved?<br /><br />c/6<br />Hooty

 

[vaughneric2000]

Re: How do you set timing advance?

Yeah, my question is confusing because I'M confused on this subject.<br /><br />Engin timing is already set. I am asking about spark advance timing. Where to set and lock the rubber stopper, in other words. I think the difference between engine timing and spark advance is 4 degrees. Manual says engine timing is 19 degrees BTDC. That has not changed. However, I don't know how you set the rubber stopper screw to obtain the spark adavnce setting-whatever that humber is. The marks are on the flywheel, and there are no marks near the rubber stopper.<br /><br />I'm sure it's very simple, but I just haven't been able to grasp how to set that timing advance stop.<br /><br />Thanks again.<br /><br />Eric

 

[phatmanmike]

Re: How do you set timing advance?

spark advance timing and timing are the same thing, if its set, dont mess it.that 4 degrees you speak is propably at idel, and the 19 is at WOT, the further you move the rubber stopper, the more advance your timing gets... its set and doesnt ever need to be moved unless its been screwed up. <br /><br /><br />how is your motor running, and why do you ask

 

[Joe Reeves]

Re: How do you set timing advance?

(Timing At Cranking Speed 4°)<br />(J. Reeves)<br />The full spark advance can be adjusted without have the engine running at near full throttle as follows. <br /><br />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). <br /><br />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. <br /><br />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°. <br /><br />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. <br /><br />No need to be concerned about the idle timing as that will take care of itself. The main concern is the full advance setting. <br /><br />Be sure to use your own engines spark advance settings, not the one I picked out of the air here in my notes.

 

[vaughneric2000]

Re: How do you set timing advance?

Hello, phatmanmike:<br /><br />Thanks for your reply about setting timing advance. You asked how the motor is running. Everything but idle is perfect. When I bought the motor, it wouldn't idle at all, and I soon discovered that the rubber stopper/timing advance screw was not on the motor at all. I purchased the correct screw w/rubber stop. Now, my engine timing is set, no corrections necessary, I think??. But since the screw was gone, I have no way of knowing if it's even close to being set correctly. And it doesn't help that I can't picture what everyone is saying when they say to: "set the timing advance" to this or that. <br /><br />What do you set? (picture here a man literally pulling handfuls of hair from his head)<br /><br />After the engine timing on the flywheel is correct, the screw with stopper is moved to adjust spark advance? <br /><br />Please read all these lines as questions. <br /><br />But what do you use to set the advance to its setting? Do you set the run the engine when it's timed properly and turn the screw until the timing light moves everything up 4 degrees?<br /><br />You see!! I just can't get that one little point clear in my head. Something is missing. I understand what the spark advance is for. I understand engine timing (at least I THOUGHT I did, anyway). Since there's no distributor on this type of engine, is the rubber stopper the only way to set engine timing at all. I know I'm asking questions about something that probably seems to you like something simple, but . . . Hey! Wait a minute . . . maybe that's it! <br /><br />When you have time, how about jotting down how to set base engine timing, and tell me as you're lining up the marks, what is moved to change or adjust the timing. I think this little piece of info has been missing. When someone says "set the timing to 4 degrees over base timing" tell me what it is, EXACTLY, that they are moving to set this,both for base timing AND for spark advance.<br /><br />Thank you! Thank you! Thank you!<br /><br />My motor runs perfectly, except for idle. Not bad for a freebie.<br /><br />Sorry for the long post, but I have just GOT to get this point!! I am a red-blooded male, after all, and Not knowing how to do this feels like pulling over to help a damsel in distress with a flat tire, and not knowing how to get the damned wheel off.<br /><br />Thanks,<br />Eric

 

[rickdb1boat]

Re: How do you set timing advance?

Are you talking about idle timing and the idle timing stop screw? I think Joe just explained that. re-read his post again carefully... <br /><br /> manuals<br /><br />this part especially:<br /><br />

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). <br /><br />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. <br />

 

[Freezebear]

Re: How do you set timing advance?

I think you are making it more complicated than it is. I do that a lot too. All you are doing is setting a minimum and maximum limit on the spark timing. At idle an engine should be set with the base idle timing screw (not sure where yours is but mine is under the flywheel mounted to the timing plate that moves back and forth). You want this to be anywhere from TDC (top dead center) or up to 4 ATDC(After Top Dead Center). Which means the spark occurs when the piston is at the very top of its travel in the cylinder or 4degrees ATDC which means the spark would occur 4degrees of flywheel rotation after the piston reached TDC. That is your base timing. <br />Now onward to Maximum spark advance. As the RPM's go up the spark needs to occur sooner in the piston's travel, before it reaches TDC. The timing will be say 19degrees BTDC(Before Top Dead Center). As you open the throttle and feed it more gas, you are also moving that timing plate proportionally to the throttle. When you have it wide open, the timing plate is all the way up against that rubber stopper. That timing is very crictical as has been stated before. It NEEDS to be verified and set correctly. What happens is it starts preignition which is bad and can be heard in a car engine and sounds like a bunch of marbles in a paint can being shook. I doubt you would ever hear it in a boat motor due to the wind and other noise. Instead you just hear that clunking sound when the piston finally melts, and then silence. I would not run the motor without knowing what the heck it's set at. Sounds like you got lucky and you probably got it real close or you're not advanced far enough which will make it kinda boggy and burn fuel. If so, when you set it right, you will feel a difference. That minumum idle timing screw is what controls the idle speed. the carbs should be closed and then the timing will control the engine speed. Hope this helps.