Wisconsin V-4 question

Fritz Maurer · Feb 23, 2017

A VP4D equipped with a distributor has irregularly spaced lobes to coincide with the irregular firing interval of a V-type engine, which is 180, 270, 180, and 90 degrees. Yet, all the magnetos in the parts list have cams arranged to fire every 90 degrees. How does this work?

Janicholson · Feb 23, 2017

Some V engines are 60 degrees between banks some are 90. (possible answer) Jim

Tramway Guy · Feb 23, 2017

On a Wisconsin engine with 'uneven firing', magnetos run at twice the speed of a distributor. Half of the time the spark occurs at the end of the exhaust stroke. Crude, but it works.

All of the Wisconsin V4 engines are 90 degree design. To get an even-firing engine, there are changes to the crankshaft.

teddy52food · Feb 23, 2017

Tramway has it right.

VicS · Feb 23, 2017

Most new cars fire on exhaust stroke also. Crank triggered.

ptfarmer · Feb 23, 2017

Otherwise known as "waste spark ignition".

Jon Hagen · Feb 23, 2017

Yes, I have one of those little odd fire Wisconsin's fitted to one of my parade tractors, a steel wheeled 22-36 MD The mag runs crankshaft speed, and has the distributor rotor directly mounted to the mag rotor shaft, not the half speed gear driven rotor of the even fire engine. It sparks every 90 degrees of crank rotation, sparking 4 times on TDC compression to fire the cylinders, and 4 times on the exhaust stroke, the 4 wasted sparks.

Wisconsin V-4 question

Fritz Maurer

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Janicholson

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Tramway Guy

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teddy52food

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VicS

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ptfarmer

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Jon Hagen

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