BGE Ignition Timing?

[Hahn007]

Hi,
I'm working on an Onan BGE spec A. The point gap is 0.16 and ignition timing is 16° BTDC. Since the ignition timing is set solely by the point gap, I was thinking about using it to accurately set the point gap on a used set of points. It would be similar to using a dwell meter instead of feeler gauges, which I would happily do if only I knew the dwell spec for this engine.

The service manual for the generator gives the timing spec but doesn't say anything about how or where to check/verify ignition timing.
Does anybody know where the timing marks are on these engines?

Thank you in advance,
Chris

[DRMousseau]

Surprisingly, the dwell is of least concern to the mechanic. It is the angle of cam rotation that allows the points an adequate time to "dwell" in contact. The duration of contact must be must sufficiently long enough to fully charge the condenser thru the coil, while majorly keeping the points apart to prevent constant current flow. Since the cam is hardened steel with very little if any surface wear from the soft "points brush", it remains quite fixed by design with a rather large tolerance for wear.

The mechanic is concerned with the repair and replacement of those parts DO wear or fail, and affects the ignition dwell and spark timing. Of most importance are the point contacts, and the points brush that rides the cams surface. While the worn, misaligned, pitted and dirty contacts can often be repaired,... the points BRUSH can not! A worn points brush causes reduced point gap, uneven contact, increasing contact wear, pitting AND increased dwell.  Dwell measures may be helpful in determining if the points brush is beyond useful wear, but that's usually quite obvious and often overlooked!!!

Dwell is most important in determining cam wear WITH NEW POINTS! If dwell is out of spec with new points,... then the cam needs to be replaced.

So jus set the gap of the "NEW" points to spec, and properly adjust spark timing. And don't forget a new condenser/capacitor,... they're cheap too, and far more involved in determining if they're good. I haven't had an analog meter in years, and it takes a good one for testing capacitors.

[Rickf1985]

Dwell is a measurement of the time the points are closed and has absolutely nothing to do with the amount of wear on the point actuator other than as an indicator that it has worn down some. Once the point gap is readjusted the dwell returns to the previously set value. The dwell is set by adjusting the point gap and can be maintained up to the point that there is no more adjustment left on the points. If you have to go with a used set of points it is best to file them with the proper point file and then set them with a feeler gauge.

[DRMousseau]

If your actuator is worn, it will increase dwell even if point gap is properly adjusted. If you adjust dwell to correct the spec, the worn actuator will reduce point gap. Neither circumstance is desirable for long point life. Adjusting contact thickness by filing and cleaning may compensate a bit for a worn actuator, but there is a limit in the point geometry that will prevent a clean, square break and eventually you'll no longer keep either spec simultaneously.

New point sets last a long time,... cleaned and filed sets, not so long. But you can always clean and adjust 'em again,.... jus gonna do it more frequently each time. If I gotta pull a fly-wheel off to get at them,... they get new! If it's jus under a distributer cap,... I'll maybe clean 'em up and pick up a new set for the next time, knowing they're in need of replacement.

[Hahn007]

Thanks Rick.
Does anybody know where the timing mark access is?

[Rickf1985]

Look up the manual in the members section, I do remember seeing it in there somewhere I think.

[Hahn007]

Been through manual several times.
They list the timing spec in the engine specifications section at the beginning if the manual.
I didn't find the timing mark location or any discussion about timing anywhere else in the manual.
The manual is a pdf, I will use the search feature just in case I skimmed over it somehow.

Thanks.

[DRMousseau]

I'm not aware nor have I seen any observation holes or ignition timing marks on early BGE 's to observe or set ignition timing. I've heard that later models were different, and I've not seen or looked at any later models with the newer electronic ignition sets.

Ignition timing in the early BGE models with mechanical point ignition is fixed by design as you noted in your opening post. A quick look in the manuals, shows all troubleshooting issues related to ignition timing, will reference you to point gap adjustment. If the points are replaced with new, and point gap is set to spec, then everything, timing and dwell, SHOULD of course, fall into spec. But this is not ALWAYS the case, and many will adjust point gap slightly from spec to improve timing a bit. Obviously, this system has little leeway and while timing may improve, point gap and dwell will be somewhat affected.

You probably noticed that point sets are rather expensive (about $25), and somewhat unique and unusual when compared to other typical automotive and small engine points. They also do not ride directly on a cam like others. I've heard that these issues lead to later model BGE designs with electronic ignition. I'm not sure they are adjustable in timing either, but they are far more dependable.

Can early models be updated with later ignition??? Not certain. It would require a flywheel change, shrouds and magnetic pickups and mounts. I believe there are after market electronic ignition kits available to modify the existing system. Don't remember the popular brand names, but they too require mounting magnets in the flywheel and the custom mounting of needed pickups. Last I recall, they cost about $150 or so.

[Rickf1985]

There was just another thread here about a electronic conversion using the points as the trigger therefore eliminating the current draw across them and extending their life pretty much indefinitely. I am going that route.

[DRMousseau]

Thanks Rick!

I would personally think that would be a far better conversion and likely allows for timing adjustment!!! If so, then I too MAY be interested in such a conversion. That adjustment ability would be desirably important IMO, since your still at the mercy of wear on the other components in the system design. Still no way to "see" the timing setting, but a good mechanic can tell what's best and will use care that it's not set too "hot" or too "slow".

Although like you said, the life of the points contact would be near indefinite, and this is the most troublesome issue that everyone deals with. And I'm sure spark would likely be improved too, thereby extending plug life as well.

[Rickf1985]

Here is a link to the electronic ignition setup from Kirk. I am putting it here because there is a way to set timing with it.

http://www.kirkengines.com/#Products

[DRMousseau]

THAT'S AWESOME Rick!!! Thanks!!!

Looking into it a bit, it seems the timing with this system is still based on the the existing timing system,... in the case of the BGE, that means setting the point gap. BUT,... adjusting the point gap for improved timing can be done without the concern of point dwell!!! And the reduced current means even minimal point gap will not be arching and causing problems!!!

And no big mods to be messin' with either!!! I LIKE IT!!!! ALOT!!!!

[lngfish]

Mine is a 4.0 BGE. This mod looks good to me. I had to adjust point gap other day it was too wide and no spark or not enough closed time to charge up coil and capacitor from what I read here. My generator is OEM, how do I test this resistance they refer to or can I assume it is within specs they require?

[Bnova]

Mine is a 4.0 BGE. This mod looks good to me. I had to adjust point gap other day it was too wide and no spark or not enough closed time to charge up coil and capacitor from what I read here. My generator is OEM, how do I test this resistance they refer to or can I assume it is within specs they require?

Use an ohmmeter to measure the resistance of the primary circuit of your ignition coil. 

Remove the 12vdc input wire to the coil and disconnect the wire going from the coil to the points (either at the coil or the points, what ever is easiest). 

Then put one ohmmeter on the input terminal of the coil and the other meter lead to the other terminal or wire that leads to the points.

[lngfish]

Bnova,

Thanks for letting me know.

Steve