Timing Advance?

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BobM
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Timing Advance?

Postby BobM » Tue Jul 23, 2013 12:37 pm

I know, KISS, Keep it simple stupid. Well my 69 square nose starts and runs OK but had issues with running smooth and bogging down under power. Compression is within 4 points at 112 lbs. Has Pedtronix Ignitor electronic ignition, new plugs, cap, rotor, coil and wires.

Number one cylinder at TDC, pointer on bottom pulley mark. Runs a little rough at 500 rpms, not bad though. Runs the same at 1,600 rpms. With throttle set at 500 rpms, timing light shows pointer on bottom pulley mark. Run it up to 1,600 rpms, pointer stays on bottom pulley mark.

Shouldn't it move to the top pulley mark at full throttle?

What KISS little thing am I missing.[size=150]
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Re: Timing Advance?

Postby RaymondDurban » Tue Jul 23, 2013 1:40 pm

At idle, it should be at the top pulley mark (TDC), and full throttle it should move down to the bottom mark (16* advance).

Set the idle to the top mark first, then see what happens when you increase the throttle. If it doesn't move to the bottom mark, the check the weights in the distributor.

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Re: Timing Advance?

Postby Eugene » Tue Jul 23, 2013 3:06 pm

Follow Ray's directions to see if the advance is working.

Under the rotor, in the center of the post it sits on, is suppose to be a wick. This wick is to be oiled - and usually not. If advance is not working, set engine on TDC, # 1 cylinder and remove distributor. Set distributor upright in vise or stand. Add quality solvent to the wick. Let set. See if the solvent frees up the advance.

You will only get about an 8 degree movement in the advance, not much more than a wiggle, when it frees up. When free, oil wick and move advance mechanism. Then oil weight and spring pivots.
I have an excuse. CRS.

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Re: Timing Advance?

Postby BobM » Tue Jul 23, 2013 5:55 pm

Thank you, I'll check that tomorrow lube up the post.

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Re: Timing Advance?

Postby pickerandsinger » Wed Jul 24, 2013 5:34 am

Eugene wrote:Under the rotor, in the center of the post it sits on, is suppose to be a wick. This wick is to be oiled
Following the post....A moment of learning, thanks to Eugene :D ........Thanks Dave
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Re: Timing Advance?

Postby outdoors4evr » Wed Jul 24, 2013 6:54 am

Since the tractor is designed to do its work at or near full throttle, you should actually set the timing at full throttle using the 16 degree mark.
It should move toward the 0 degree mark at an idle. If it doesn't make it all the way down to the 0 degree mark then that's ok. Live with it being off a bit at an idle. The tractor is not "doing work" at an idle and will still start very reliably.
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Re: Timing Advance?

Postby Eugene » Wed Jul 24, 2013 7:09 am

outdoors4evr wrote:If it doesn't make it all the way down to the 0 degree mark then that's ok. Live with it being off a bit at an idle. The tractor is not "doing work" at an idle and will still start very reliably.
At engine cranking speed the ignition system needs to fire at 0 crankshaft degrees, or perhaps a tiny smidgen of a degree later/after. Should the ignition system fire the piston before TDC at engine cranking speed - hard start or no start problems.
I have an excuse. CRS.

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Re: Timing Advance?

Postby outdoors4evr » Wed Jul 24, 2013 8:12 am

Checked my service manual.
Spark advance @ 400 rpm............0-1 degrees
Spark advance @ 800 rpm............4-8 degrees
Spark advance @ 1200 rpm............10-14 degrees
Spark advance @ 1600 rpm............15-16 degrees

If using a timing light, and verifying the RPM's as you are measuring then timing your engine is easiest (and best) at working RPM's.
I notice it doesn't give a specification for higher RPM's even for the numbered series tractor engines. If you have the 16 degree mark on your front pulley and can set the timing at 1600 rpm's, then the rest usually works out okee dokee. I don't worry about the idle because I may not get my tractor to purr down to 400rpm. Just make sure the timing advance mechanism functions and the timing is being retarded at the lower RPM's.
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Re: Timing Advance?

Postby BobM » Wed Jul 24, 2013 10:05 am

Thank you for the input. I won't be able to get to it until Monday. I will take all the input and get it straightened out then and report back.

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Re: Timing Advance?

Postby bythepond88 » Wed Jul 24, 2013 12:20 pm

Eugene wrote:At engine cranking speed the ignition system needs to fire at 0 crankshaft degrees, or perhaps a tiny smidgen of a degree later/after. Should the ignition system fire the piston before TDC at engine cranking speed - hard start or no start problems.


Ditto this remark. I static timed my dist, then put a timing light on it to make sure it was getting proper advance. It was a few degrees short, so I adjusted the dist. That changed the static time, and, as Eugene says, I started having starting problems. Re-did the static time, and she was fine again. Not sure what changed since (probably the fact that I decided to change the points and condenser shortly after and oiled the felt), but she is now advancing properly at high idle.

Lesson learned, make sure the static timing is correct. If you can't get proper advance, then there is something else wrong.
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Re: Timing Advance?

Postby kpaine » Wed Jul 24, 2013 2:45 pm

Eugene wrote:Follow Ray's directions to see if the advance is working.

Under the rotor, in the center of the post it sits on, is suppose to be a wick. This wick is to be oiled - and usually not. If advance is not working, set engine on TDC, # 1 cylinder and remove distributor. Set distributor upright in vise or stand. Add quality solvent to the wick. Let set. See if the solvent frees up the advance.

You will only get about an 8 degree movement in the advance, not much more than a wiggle, when it frees up. When free, oil wick and move advance mechanism. Then oil weight and spring pivots.


Not trying to hijack the thread and I am a novice mechanic, but how to you advance #1 to TDC? Pull the spark plug and rotate crank until the piston is at the top of the stroke? Sorry for the dumb question.

Ken

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Re: Timing Advance?

Postby Eugene » Wed Jul 24, 2013 4:35 pm

kpaine wrote:Not trying to hijack the thread and I am a novice mechanic, but how to you advance #1 to TDC? Pull the spark plug and rotate crank until the piston is at the top of the stroke? Sorry for the dumb question. Ken
In this instance the engine is capable of running.

Remove distributor cap. Rotate engine by hand until the rotor points to the previous #1 spark plug wire location when distributor cap was installed. Check and line up the pointer and TDC mark on pulley by hand.

If engine is not capable of running. Finger in #1 cylinder spark plug hole. Rotate engine until compression felt. Then line up pointer and TDC mark on pulley.
I have an excuse. CRS.

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Re: Timing Advance?

Postby BobM » Mon Jul 29, 2013 9:01 am

To follow up, I static timed my 69 Square Nose. With a timing light, at 1,600 rpm's the pointer is on the bottom pulley mark. At 500 rpm's, it remains on the bottom mark. I have removed the distributor and lubed the wick. I will continue to lube it and spin the distributor manually several times through out today and reinstall it in the morning to see if it frees up the weights.

If not, I guess I will have to disassemble the distributor to free then up???????

Thank you for your help and suggestions.

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Re: Timing Advance?

Postby John *.?-!.* cub owner » Mon Jul 29, 2013 9:42 am

Bob, under the plate the points mount on are weights and springs that cause the advance as it speeds up. The shaft the rotor and points operate with is actually a separate shaft form the one that drives the distributor with one shaft being inside the other. That may be gunked/rusted and need to be cleaned and lubed. with the engine not running you should be able to use your hand to turn the rotor forward and backward a few degrees, with the springs returning it when you release it.
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Re: Timing Advance?

Postby BobM » Mon Jul 29, 2013 10:17 am

Thanks John. I've never had that plate off and was a little concerned that I may screw it up if I went digging in there.

I just went out and held the drive gear and turned the shaft. It was stiff. I lubed it again and worked it several more times. It appears to be freeing up a little. I will continue to lube it and move it for the rest of the day and reinstall it in the morning.

Thank you again.


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