MTFCA Forum

Has anyone run a DU 4 without an impulse coupling

yes I have... we have 5 different cars with that mag and no impulse. 1912 Case, 1913 Case, 1911 Franklin and a '06 Franklin. I have also worked on a few early Buicks that are the same setup.
Harold.

1912 Buick been running for over 60 years that I know of. Do you need a du4 ?

I have a 13 T speedster with a Bosch DU4 side drive/ no impulse. No starter so you have to flip it fairly quickly to start.
With the Sherman Superfire head and Winfield carb it was a bit tougher to start.
I changed out to a stock (milled) 13 head and Holley carb for the 2008 Centennial. Much easier to start now.
If you were using a starter there should be lots of cranking speed to fire the plugs.
I am setting up another DU4 to run with my RAJO 4 valve.
In my opinion the Bosch magneto is the best Model T ignition system I have used.
Harry

Used to run a DU-4 on my ol’ 27 roadster with a Matco front plate without impulse coupling. Hand cranked the basically stock motor many times, and always started well.

Just a hunch... but I suspect many hard starting “ignition” issues are fuel related

Thanks for the input. I have a few of them and thought I would rebuild one and give it a try.

I run a ZR-4 on my speedster with a starter and 9:1 compression. No impulse and starts up great.

I run 2 cross drive front plates with a DU4 and no impulse. Never a problem. I love them ! I am doing another and going to use a “from the front seat” starting mechanism, and no starter motor so I am going to install an impulse, 1) because I have one 2) it may help just a bit. Keep in mind, most impulse couplings are left hand or right hand, and a very few can be switched easily and go either way. Another thing to get your mind wrapped around. Same with the mag itself, the side drive turns opposite of the front drive.

Starting a Rajo with a DU4 and no impulse coupler. https://youtu.be/5vgjgQQmHds