Bosch Front Plate Magneto Gear Drive

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Model T Ford Forum: Forum 2013: Bosch Front Plate Magneto Gear Drive
Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Friday, August 30, 2013 - 08:26 am:

Question - after a rogue key ate my magneto coil, I decided to remove it and go to a DU-4 mag on a Bosch triple gear drive. The car is about 90% back together with only a few things left to do - I have to manufacture my spark advance linkage (not a big deal) but the part I'm wondering what other's have done is the actual driving of the big gear on the cam?

Right now the only thing I have is the pin from my Anderson timer. There's a nice slot in the big drive gear, but the head of the pin is too wide to fit in there. What I really need is a like a square woodruff key with cam-hole sized pin sticking out of the middle of it, making a T shape.

Ron White, or anyone else running one of these, what did you use? I had Mainely Magnetos rebuild the build as well as add an impulse coupler. When I slowly turn the unit by hand, there's a pretty good bit of resistance from the impulse coupler. Combined with the way the gears get smaller as they move away from the cam, it makes me think that if I just file the head of the pin to fit in the slot, it'll just shear off when I try to crank it the first time.

I know this may be hard to read and follow. Will post pictures tonight.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Friday, August 30, 2013 - 08:40 am:

Also - if anybody has any recommendations on how to get the timing as close as possible I am wide open to any input.

Unless I hear differently I'm going to get the engine to just before TDC on compression and the mag set to just before firing on #1.

The impulse coupler is set up so that when I have the mag turned to almost firing on #1, the ratchet is catching, I'm just not sure how far the engine will turn past TDC before the coupler lets loose and #1 fires.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, August 30, 2013 - 09:13 am:

I try to get the impulse to let go as close to TDC as I can. The impulse typically has 30 degrees of retard. So, if the impulse lets go at 1 after TDC, you will have 29 degrees of advance, which should be pretty close. I then put a degree tape onto the pulley and check the timing with a timing light.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, August 30, 2013 - 10:04 am:

Light aircraft with magnetos have impulse couplings and typically about 30 degrees fixed advance, and timed about like Tom does it. You may not need variable advance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Friday, August 30, 2013 - 10:50 am:

Get the #1 coming up on compression and using a degree wheel bring it to 30 BTDC. The mag then needs to be set to fire the #1. To do this you must click the impulse coupling until it sparks #1, then back it up slightly but not enough to re-engage the coupling. You will feel the magnet align poles. Now it is ready to fire #1.

You can bolt it up and as Tom has said, dial it final with a timing light or you can disconnect the primary lead at the points and connect an ohm meter to it. When the points indicate open, that is where it fires. Lock it down and your good to go. If you can't access the points (such as with a Slick) you must then use an aircraft style timing light to break down the primary as it is grounded at both ends and your ohm meter won't tell you anything with the points connected to the primary.

A word of caution to anyone fooling with magnetos. Do not allow the impulse coupling to click without the plug terminals grounded or attached to a grounded plug. Think of a spark plug as a safety gap. Without the gap the energy is dissipated within the secondary windings. It is also for this reason that the plugs should be gapped at .016-.018 for most mags. Opening the plug gap further will cause early mag failure. I know you will get guys tell you that "all T's should be between .025-.032". You will be the one writing the check and not them.

Back to your original issue about getting the timing as close as possible. The procedure above will be exact. I have installed bunches of mags on airplanes and that is how they are set. There is no checking or adjusting while running on an airplane.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Friday, August 30, 2013 - 10:54 am:

I agree with RD. With an impulse coupling 28-30 non adjustable timing should work fine. The previous post is for fixed timing, not variable.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach & Big Bear on Friday, August 30, 2013 - 11:09 am:

spark plug gap should be at .020" . I found the plans for a magneto tester in Dyke's and made one up. You adjust the gap to the plate by turning the screws up and down. Turn the mag with a rubber hose on a 1/2" drill. either end wing nut is the ground wire.

.



mag DU4

Here are two spark adjusters below.

Two different spark advance systems shown below. I have more pictures if you need them

spark


Spark control. Spark rod comes across in front of the engine and grabs the short bell crank. The curved one runs the magneto.


DU4


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Friday, August 30, 2013 - 03:35 pm:

Seth,
I didn't notice anyone clarify the gear mounting on the cam. I have never had one of these. But I think they require a special camshaft nut that provides the key and strength to run the mag. It would not be very difficult to make one.
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Sunday, September 01, 2013 - 07:29 pm:

Hey Wayne, I got everything together and made my own pin/key combination. It worked for about 3 revolutions and then sheared apart. I'm excited cause I know I'm close but frustrated because it took a long time to make that stupid little part.

Wayne or anyone have a suggestion on exactly what to make? I'm trying to have the car running by next weekend for a tour. I was afraid it would fight me like this.


Top of pagePrevious messageNext messageBottom of page Link to this message  By clayton swanson on Sunday, September 01, 2013 - 07:46 pm:

you make a nut from hex stock, 1 1/4 i think, or the same size as the normal t cam nut, but with the dogs to drive the gear.i made some before and have the print here somewhere, i'll look


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Sunday, September 01, 2013 - 07:50 pm:

Here are some pics. As I sat there looking at it and thinking about it, I was wondering if I get another nut for the cam, use a pin to just locate the gear, then tighten the nut down and weld a small arm onto the nut so I can put a bolt through the arm and one of the holes in the drive gear?







Even my idea would let the cam slip a little as it tightened some on the nut - just not sure what to do. Whatever it is will have to be pretty strong because the impulse coupler spring is SERIOUS.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Sunday, September 01, 2013 - 07:52 pm:

Haha, I guess I was putting my post together when you posted Clayton. If you have a picture or something it would really help.

Wide open to any ideas at all.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Sunday, September 01, 2013 - 09:56 pm:

Bump


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Monday, September 02, 2013 - 12:09 am:

Clayton S' idea sounds good. A small lathe would do it. It could be done with a drill press, proper tap, and a Dremel tool. Measure carefully. Trim. Measure carefully. Trim. Figuring out how to make what you need with the tools you have or can get is half the fun! It could be made in pieces and welded together, but that is not really a good idea for this. It needs to run true and be very strong. Although it does sound like something I would do. I did weld together a transmission to drive-shaft coupler once. It has long since been replaced with a real part.
The nut you make will have to have a shaft to support your gear, and the keyway to drive it. The nut and shaft should all be one piece made from hex or round stock.
Good luck!
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Kerndt on Monday, September 02, 2013 - 09:38 am:

I run a Bosch DU-4 on my 1915 with a Cross Drive and eliminated the impulse coupling as it was too difficult for me to time. Runs and starts great. Just my 2 cents worth. Bill


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Kerndt on Monday, September 02, 2013 - 09:48 am:

I run a Bosch DU-4 on my 1915 with a Cross Drive and eliminated the impulse coupling as it was too difficult for me to time. Runs and starts great. Just my 2 cents worth. Bill


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach & Big Bear on Monday, September 02, 2013 - 12:21 pm:

We find that the impulse snaps the spark and when you use an impulse you do not have to spin the engine, Simply turn it by hand and it will start.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Monday, September 02, 2013 - 04:30 pm:

So I figured out something and got the car to start and run no problem. It is still really bizarre to see something on the side of the engine spinning. Anyway after a test run I decided I was close but probably needed another tooth or two of advance. The engine idled really well with the spark lever fully advanced. So I guessed and added two teeth - bingo. It idled much better and I'm sure will get up in RPM better when I get the radiator back on.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerome Hoffman, Hays KS on Monday, December 16, 2013 - 03:21 pm:

Seth, any update on your efforts? Jerry


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Monday, December 16, 2013 - 04:35 pm:

This thread interests me as I have a new mag for a Wisconsin V-4 engine,and wonder if it could be adapted to a T engine?


Top of pagePrevious messageNext messageBottom of page Link to this message  By joe bell on Monday, December 16, 2013 - 06:04 pm:

I played with a du4 recently and had a heck of a time with, then changed out the plugs to the old X's and it fired right up??? installed the modern ones after I had it running and it would not run?? Made no sense to me!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Monday, December 16, 2013 - 06:08 pm:

Hey Jerome - I've actually driven the car on a tour and all over the place since that last post in September, she cranks and runs and drives like a champ. I had it running with no problems once I posted that. It is incredibly reliable and gives me zero issues. The gears up front are a bit noisy, I think it's because they're straight cut and a little worn, but it's only noticeable if you have it next to another T.

The only thing that has happened to the magneto is that there WAS a little brass door on top that covered two little oil holes, at some point the screw that held it in place I guess vibrated loose and is gone along with the door. I was really annoyed. I actually just won 2 more DU-4 Magnetos on eBay (a complete one that is in great shape minus the distributor button for $34!). I'm going to send it to Steve at Mainely Magnetos to have it completely rebuilt and ready as a backup to the one on the car, the other was just for the parts - I want to have the big black magnets brass plated and then recharged, and then I will swap them for the ones on the car! It'll look really spiffy. I'm also going to use the parts one to replace the piece that actually holds the little brass door - the tapped hole where the screw was is stripped, I think that's why it vibrated out in the first place. Once replace that I'll have a good threaded hole and new door on top. Plus, I'll have plenty of extra parts should I ever need anything.

Honestly, having a whole magneto as backup is probably way overkill, but on my last tour it was pointed out that even though lots of people have extra coils/timer/anything related to stock ignition, if my magneto acts up no one can help me. I won't really know what is wrong apart from something obvious and easy to fix, so I figure I'll just have 2 nice mags once I get this one rebuilt. One will just ride in the tool box.

Finally: the performance of this mag is AMAZING. I can rev the engine as far as I dare and the mag never misses. It would redline long before I ever ran past the mag's ability to accurately provide spark. I really like it, it's one of my favorite things I've done on the speedster. The impulse coupler that Steve added makes it a breeze to hand crank. Really, when I goof up cranking the car, it's because of the carb, not the mag. Plus, not many folks with speedsters (that I've seen) run a high-tension mag, they all have distributors. So it's cool from that aspect as well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Monday, December 16, 2013 - 06:12 pm:

Hey Joe - just FYI - a magneto requires that the plugs be gapped really closely, much more so than a distributor or the stock T ignition. I have my Champion plugs gapped at .018". If you try to run the mag with the plugs gapped too wide it will fry the secondary coil and the whole thing will have to get gone through and rebuilt. I make no claims to being an expert on these but have learned a few things after fooling with mine. From what I understand a lot of folks unwittingly fry their mag because they spin it with a drill to test it and they either have the plugs gapped too wide or don't have it hooked up to plugs at all, which is a big no-no.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Monday, December 16, 2013 - 06:16 pm:

Oh, right now the car is all apart cause I'm fooling with all kinds of stuff, one thing I've been contemplating is cleaning out that white lithium grease on the gears and running something a little thicker and heavier to see if it helps them quiet down at all. I want to replace that grease cup with a brass one that has a zerk fitting, that way I can just grease gun the gears, my U-joint, drive-shaft bushing, and rear axle bearings all with the same gun.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Monday, December 16, 2013 - 06:54 pm:

Joe
Spark plugs
My understanding is that "resistive" spark plugs are not very good with high tension magnetos. If you go to some of the manufacturers technical web sites your will find more information. I discovered this looking for spark plugs for a application I was researching.
Considering that most new car plugs are of the resistive type to reduce interference with radios etc, this may be your problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By joe bell on Monday, December 16, 2013 - 09:08 pm:

Thanks again Les for your imput, never thought of that one but it does make sense!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Tuesday, December 17, 2013 - 09:48 am:

Congratulations, Seth, on converting your car to the way it should have been built in the first place..

.

.

..Ducking away from this thread..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Tuesday, December 17, 2013 - 10:15 am:

LOL! That's good Ricks.


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