Timing 1910 Hupmobile

[Seldenguy]

The 1910 Bosch's ranged from Serial #434,567 to 646,345. --Bob

[Max BURKE]

D,day to all.

Brief check of the moving point. The point must always lead the rubbing block in either rotation direction. The rubbing block must always trail. The trailing edge of the bobbin should have left the pole shoe by 20 to 25 thou with the points just opening. As said the combe tooth pole shoe on later DU4 is to entice a strong spark over the advance/ retard range. The two keyways in the mag driver gear are for a half tooth variation. My view is the fixed spark cam on mod 20 was used on cost alone . No links to reach from magneto to driver ,no lever to confuse the operator which way is start. I have not driven a Hup 20 that was not improved by fitting variable spark. If the Hup price rose folk bought a FORD .We run a dual spark Simms and fire two plugs together on our mod D and we run a Splitdorf Dixi on the 1911 roadster. Both are variable spark. We run 7/16 piston advance when on full spark advance which gives 1/8 late on retard. We vary through this range when driving. Happy Hupping to all. Max BURKE Nulkaba 2325 AUSTRALIA

[Hubert_25-25]

Looking for a little more direction on timing a Bosch DU4 magneto and placement of the rotor relative to the "Segments".  The following pages from Dykes are a little confusing.  Just verifying that the "segments" are the brass sections that the rotor fires against.  On page 294, the segments appear to be the brass sections on the distributor cover.  On page 298, it looks like they are setting the rotor on the insulated section between the brass.  So is it safe to assume that with the motor on TDC, the rotor should land on the #1 brass segment when I am on full retard, and the points are just opening.  In addition, when I rotate to full advance and check that my points are just opening, my rotor should still be on the same #1 brass segment.   Thank you,    Hugh

    

[1910Hupp]

Yes the segments  referred to are the brass segments .

Hupp has a funny way of setting the fixed  timing -If you follow the  instructions in the  manual  you actually  find tdc and then  continue to  rotate the  flywheel  by about 5/8 of an inch   and then you set the magneto up to fire on Number 1 Effectively the ignition is retarded when set up . I have fiddled with variable ignition  and set it up as per the instructions but set the variable  timing at full retarded at that point .Interestingly it  runs  best and starts best  fully advanced  so  I just leave it there  

[Hubert_25-25]

Karl, 

   Thank you for the the clarification and the timing set up description.   The fixed timing magneto is interesting.  Not the best in my opinion.  If you have the spark occur retarded and after TDC (by 5/8") you have prevented the engine from rotating backward, but now you have decreased power and the chance to burn the exhaust valve and the engine runs hotter.  If you set the car up for best operability (Advanced and firing before TDC) , you run a greater risk of injury during cranking.   Many cars do start easier with the timing advanced, but there is a greater chance of injury to be aware of.  Using proper technique of pulling up during the start is very critical.      Hugh 

Edited March 1, 2021 by Hubert_25-25 (see edit history)

[1910Hupp]

This afternoon I set up a timing light and looked at the flywheel  position when fully advanced which is were I run it all the time -I'm getting about 28 to 30 degrees  of advance. It doesn't   kick back at this setting.

I was taught at a young age how to crank a car by my father -However I see  videos all the time of people with their thumb over the crank handle   and  pushing the crank down as the  spin the engine  and shudder . As an MD I've seen  my fair share of wrist and thumb fractures  and they can cause long term problems -

[Hubert_25-25]

I wonder how much the speed with which a person rotates the crankshaft is protecting a person from kickback.  The flywheel has sufficient mass (momentum) that will counteract some kick back if it is rotating forward.  The trouble may be if a person did not pull the crank up fast enough.    

[Hubert_25-25]

Karl, 

      I finished connecting the magneto to the car today and setting the timing.  I am working on a 1911 Regal Underslung but this was a good thread about DU4 magnetos.  Lots of things wrong with the car. 

An Oldham coupling is required to connect the engine to the magneto.  It has to be able to move in 2 planes of motion, and it was only cut with one slot instead of two perpendicular to each other, so it would have created long term additional wear on the bearings.   They also had the timing set to always fire in the compression or intake stroke.  Not a good idea when you need to hand crank start the car.  They also used a model A bracket for the carburetor which had no throttle stop screw, so there was no way to set the idle.  And they had a spring on the mixture screw that was too long and did not allow the needle to approach the jet, so it was just dumping fuel.  The car did run briefly, but is was so bad that when I removed the carburetor and opened it, the float area was filled with soot which indicates that it was firing in the intake as well and burning the fuel inside the carburetor.   Ran out of daylight but was idling well by the time we finished and had good power when you opened the throttle. 

Thanks again for your help.

Hugh      

 

[1910Hupp]

Looks nice - Setting up the magneto is a pain -I'm always amazed  at how  a small  change  in the magneto drive  as   you  connect everything up  changes the timing so much . A tooth off makes a big difference.

They always seem to move for me as  I  bring the  camshaft gear and magneto  drive together on the Hup  -One day I'll  make a jig to hold the drive fixed  as i connect -Karl