Setting magneto gap

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Model T Ford Forum: Forum 2008: Setting magneto gap
Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Morse on Sunday, January 25, 2009 - 05:15 pm:

I can't say it's a terrible job, just a lot of doing and undoing! I think I might finally have it, but I'm looking for your opinion...

Before I installed my transmission I set magnet heights with a gap tool (unknown brand). I also checked the mag ring and it was within a thousandth or two.

I know the manual says to set the gap between .025" and .040". I attempted to get a gap of .030 at the top and a few more thousandths on the bottom. In one position I've got .032" all the way around. I turn the engine 45, 90, and 180 degrees and then I end up with .026 as the tightest (on top or sides) and one field on the bottom gaps out to about .041 for a turn of just a magnet or two. For the most part gaps run between .027 to .032 on the upper part of the ring and .029 and .037 on the lower part of the ring, except for the few outliers. But, I'm worried about those outliers.

First, can I safety wire it together and call it a day with these results? Second, why the deviation?

Thanks to anybody willing to comment!

Mike


Top of pagePrevious messageNext messageBottom of page Link to this message  By bill leahy on Sunday, January 25, 2009 - 06:33 pm:

mike,

that sound as though you may have a bent field coil or magnet height problem. i just finished the same job. it was an experience i would prefer not to repeat too soon. i started with the motor on it's nose on blocks but quickly switched to the setup in the photo when i realized how difficult it is to get up and down from the floor when replacing the fly wheel bolts. i finally ended up with a clearance of .030 on the top and .036 on the bottom. sorry for the poor picture quality. also i give credit to a prior post for the lifting technique.

bill
field coiltrans


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mack Jeffrey Cole on Sunday, January 25, 2009 - 06:41 pm:

yea,on my next 1 I will be useing some type of lifting device.That lifting on and off 2 dozen times got old and painfull to me in several ways.
Thanks for posting that lift idea as well.Are those C clamps on the transmission?I hope this dont double post,I am working with a 30.2 kps connection speed today for some reason


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush on Sunday, January 25, 2009 - 06:51 pm:

One thing that might help speed things up; leave the coil ring loosely bolted to the block, mount the magnets/transmission/flywheel. The coil ring will stick to the magnets. Measure the gap between the block and the coil ring. This should give a real good ball park number for thickness of shims.


Top of pagePrevious messageNext messageBottom of page Link to this message  By paul griesse on Sunday, January 25, 2009 - 07:23 pm:

Mike----I`d say you are "good to go" on your mag setup. Anything in the .020 to .040 range will give you a good mag. Paul


Top of pagePrevious messageNext messageBottom of page Link to this message  By bill leahy on Sunday, January 25, 2009 - 09:50 pm:

mack'

yes they are 4" c clamps. i don't take credit for the idea, but it sure made things easier. i did add an extension on my lift to get the hook positioned over the engine. once it was in place with a bolt finger tight in the crankshaft i was able to turn the whole thing to install, rotate and tighten the crankshaft bolts. this was done while sitting on a roll-about stool. much easier on me.

bill


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Sunday, January 25, 2009 - 11:19 pm:

Mike

If your crankcase endplay is correct and your magnets have been recharged you'll be fine. I speak from experience having run an engine with gaps of 0.020 to 0.045 with an output voltage of 9 volts at idle and 29 volts at high revs.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, January 25, 2009 - 11:53 pm:

Mike,
Depends on what is causing the problem. When you rotate the crankshaft, does the tight and loose magnet move around with the flywheel, or is it in the same place on the ring when the flywheel is turned? If it is on the same place on the ring, your ring needs shims to move that portion of the ring closer or farther from the flywheel, if it is on the flywheel, are the low and high magnets opposite each other or near one another? Also, what happens if you reverse the postition of the flywheel in relation to the crankshaft? The reason I am trying to find out if you have a low and a high pole on the flywheel, if the ring has a high and low spot, or if the crankshaft flange is crooked? I hope I haven't confused you. The easiest thing to fix is the shimming of the ring, and the next easiest thing to fix is a high magnet on the flywheel, next would be a low magnet on the flywheel, and hardest would be to correct a crankshaft flange that is crooked in that order.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By george keyes on Monday, January 26, 2009 - 04:39 am:

I had to turn the flywheel 1/2 turn on the crank and that made it better, but I was still getting a variation of clearances, so I made up a mount and used a compound-crossslide drill press vise and mounted a 4" angle grinder on the pan rail and ground the retaining plates, turning the crank by hand and moveing the grinder out at the same time. Got the variation to about 1-2 thou. I will try and post a pic tomorow night. George


Top of pagePrevious messageNext messageBottom of page Link to this message  By needTool on Monday, January 26, 2009 - 09:12 am:

krw1


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Morse on Monday, January 26, 2009 - 09:18 am:

Thanks all for your responses. Mark, that seems like a good way to get close on the shims. I'm beyond that stage now, but will try to remember that trick for next time.

Norman, the gap moves around with the flywheel, but the .040+ gap doesn't stay that "gappy" as you rotate it around the ring. It just may be that the crankshaft flange is crooked.

It's a total rebuild so I've got new main bearings and proper end-play, etc.

I think I'll spin it a few more times and check gaps just to make sure I don't have any less than .025 or any others that are >.040. If I'm within that range then I'll safety wire it together- oh yeah, after I remember to re-install the inside oil line...

Thanks again for your thoughts on this. I knew it wouldn't be perfect, but I wanted to make sure it was reasonably correct!

Mike


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, January 26, 2009 - 10:40 am:

If it is the flywheel flange, it will throw the entire transmission off center. You need to address this problem so that everything is in balance and the 4th main at the rear of the transmission does not run out. Otherwise, you will put a strain on the crankshaft.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis on Monday, January 26, 2009 - 01:49 pm:

When I did mine, I didn't have the transmission on there. I just removed the flywheel each time. Seems like I did use the tranny shaft to give the bolts something to hold onto. Don't remember exactly, but I know I didn't have the tranny on there. It's not near as big a deal to remove the flywheel by itself.

As for the gap, that was one of the things in the back of my mind when I started the "Preaching what you practice" thread. I don't recall now exactly what I ended up with. Seems like it was a couple of thousanths outside the given range on both ends. But frankly, I was 'bout tired of messin' with it. Yeah, I'm a tinkerer, but doing the same thing 6-8 times gets monotonous. I got it as close as I could and left it there. When I got the thing back together, it ran on magneto. It idles on magneto and will crank on magneto. That's good enough for me. I haven't done the light bulb test, but I do want to try it sometime when I'm tinkering.


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