Bosch mag drive info

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Model T Ford Forum: Forum 2017: Bosch mag drive info
Top of pagePrevious messageNext messageBottom of page Link to this message  By bob middleton on Sunday, March 19, 2017 - 09:12 pm:

Looking for info or help in setting up the 3 gear Bosch side mag drive.
I have search past forums
My questions are
What a good seal at the cam Shaft?
Is there a spacer used hold the cam main drive gear
To keep it from wearing on the case?
How to time it I don't see any ref marks on the Gears?
Will I need an impulse in the Drive?
What kind or grease should I use in the case?
Did I just use the timer pin in the cam?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, March 20, 2017 - 12:24 am:

Hey Bob, I run one of these on my speedster. It's a great accessory but I had to tackle all of those same issues you're asking about (with very little help!)

- Camshaft seal: there's a groove on the backside of the case for a felt seal. I never could get this to really work well and in the end I just use some Ultra Black on the outside of the case and it squishes up against Ford cam gear cover.

- Cam gear cover: you haven't mentioned this but the triple gear case only works with very early cam gear covers - the oil filler neck has to be really short. If you don't have the correct one Kevin Pharis makes them just for this application.

- Spacer/timing pin: the large gear in the case slides onto the end of the camshaft. There's a shoulder on the camshaft and a matching one on the backside of the gear and this positions it correctly within the case so that no spacer is needed. Also, you'll have to modify a timing pin so that it fits in the slot of the gear. All the pin does is orient the gear. You just crank the nut on nice and tight and that holds the gear in place. I don't use a torque wrench, but I tighten it to about the same feel as the head bolts, so 50 ft-lbs.

- Timing: Good luck! Hahaha just kidding, kinda. I could not find any kind of timing marks on my gears. So, in the end I just brought #1 to TDC on compression, then turned my Bosch mag until it was right at firing on #1, then slide the big gear into place. It's a bit of a juggling act getting the big gear to slide on the pin while also not letting the other two gears move. Then I tried to start the car. I don't have a starter so there was lots of hand cranking. It didn't work at first until I finally tried advancing the spark. She'd run ok, but I ended up needing to advance it by two teeth on the big gear compared to the center gear. I just used a black sharpie to mark it. It helps to have the rear drivers wheel jacked up so you can rock the engine backwards (also helps to have another set of hands, but I did mine all by myself and without this nifty guide I'm typing). If you have a starter, awesome, if not, don't be afraid to experiment with the spark lever in order to get her to run, then you advance or retard as necessary. Once you get it right, you can move #1 to TDC, and add punch marks to your gears.

I very very rarely take this part off, and the times I've had to, I just get #1 to TDC and then sharpie the gears. Haven't had any issues that way.

- Impulse Coupling: I can't speak authoritatively here as I haven't had a magneto without one. However, I've had some people say that an impulse isn't necessary. My gut recommendation is if you have a starter, skip the impulse coupler. If you don't have a starter, get an impulse coupler. Your mileage may vary.

- Grease: My gears were badly worn, the teeth were sharp and pointy so there was lots of slop and play in them. I had a new set of gears made and the gear guys highly recommended I run them in oil. So, I use Ultra Black and seal the case against the cam gear cover, and then seal the triple gear case cover as well. I use 75-140 and Lucas. Just pour it right into the grease cup and it slowly drains its way into the case. I fill it up around 7 or 8 times before I try to drive at length (I don't worry about it for testing or setting timing). I know there's a decent amount in there and every now and then when driving I fill the cup up with oil or Lucas. Eventually it fills up enough that I get some from the shaft and it weeps onto the mag platform so I know I've got plenty in there. I fooled around a long time with making a better oil fill spot just so it'd go in faster and be easier but just couldn't find a spot anywhere I liked and was loathe to drill a hole anywhere in the case anyway. It really doesn't take very long to fill through the stock grease cup anyway. Whenever I crank the engine it kinda sucks whatever oil is in the cup down into the case.

I do know it works and works well cause I've taken the cover plate off and had a good volume of oil in there. Just make sure you let the Ultra Black set for the full 24 hours when you put the cover on.

Keep us posted with how it works for you!

(Message edited by Wreckrod9 on March 20, 2017)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, March 20, 2017 - 12:39 am:

Oh, if you're running a Bosch DU-4 magneto, you'll have to fabricate your own spark advance linkage. That was a bit of an adventure for me as I only had some other photos to go off of. Mine originally was on a stock exhaust manifold and I took pics after making it work with my dual exhaust manifold. It'll at least get you going in the right direction.

On the Bosch mag when the little arm is down, that's retarded, when it's up, that's advanced.









And for fun here is a more recent photo of the same engine. UPGRADES BABY



The triple gear and Bosch mag and the dual exhaust are all still there. Just harder to see with the Rajo 4 valve and dual Zenith carbs (which are in the middle of being replaced with dual U&J carbs!)


Top of pagePrevious messageNext messageBottom of page Link to this message  By bob middleton on Monday, March 20, 2017 - 01:07 am:

Seth thanks much I was thinking gear lube as well
My gear are excellent
I pretty much surmised these answers just feel better hearing them
My car has a 16 block yet I have both mag mounts for that right side location.
I will be listing it soon
Again thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach, CA on Monday, March 20, 2017 - 01:29 am:

Here is a period correct advance/retard system in the correct position. The right end connects to the timing rod rather than the timer and the rear lever connects to the magneto. Yes it is for a Busch DU4.

link


Here is a mag spark checker made from plans in the 1918 Dyke's manual. Simply adjust the lengths of the bolts and see if they are all equal. You will need a smaller spark plug gap and can measure the gap on the bolts and use that for your plugs.

spark checker


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