idenity of type of wisconsin engine

Bought a 2 cylinder wisconsin engine with clutch. the model is T H spec 136972, 3 1/4 square engine. My question is does it fire 1 cylinder each revolution (360 degrees apart) or fire 1 then 180 degrees fire number 2 then 540 (1 and 1/2 revolution) as a John Deere. Wisconsin makes both types of crankshaft for this series of engine . The fire each revolution is smoother for generator use. Thanks fellows Bill Wilson

you might post down on the stationary engine forum too....

If it's a THD it fires evenly - once every revolution (fires every 360 deg)

A TJD however fires at 0 and 180 deg, then goes 540 deg (1-1/2 revolution) before repeating - same as a 2 cyl a John Deere tractor.

The THD was commonly used on generators where smooth power flow is important. (The TJD's higher fluctuations in speed could cause lights visibly flicker.)

The TJD was used in applications like balers, kal trucks, where RPM fluctuations did not matter much.

always wondered why a john deere had such a unusual exhaust sound. what is the reason for this cycle?

John - The reason is to reduce engine vibration.

An even firing 2 cylinder, 4 stroke engine has both pistons moving up and down in unison. Even with counterbalancing this causes a powerful vibration in the plane of the cylinders. So while the power impulses are smoother, the engine will vibrate heavily. (If you ever spot an IH Titan or Mogul - 2 cylinder, even firing - tractor running look at it closely. You will notice the entire machine literally shakes forward and back a good 1/4" in time with the flywheel when idling.)

Now by arranging the crank pins 180 apart, the pistons now always travel in opposite directions. This cancels good portion of the vibration caused by the pistons/rods. The tradeoff of course is uneven firing impulses.

In the case of a John Deere tractor these uneven impulses are smoothed somewhat by using a very heavy flywheel.

Another reason for going to 180 crank throws is to reduce crankcase pumping. If the pistons are traveling together they pump air in and out of the crankcase and cause more pollution.

sorry - editing this - I misread your question. Don't know WHICH version you've got!


BUT - if I'm correct - you should be able to tell by watching the plugs. (or looking under the cap to see how it's wired)

IF both plugs fire together it'd be the 360 degree version. If they fire independently it'd be the other.
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Not sure - but if it's similar to a TF, and I think it is...

Both pistons are even with eachother - and both plugs actually fire together.

but one cylinder is on its compression stroke while the other is on its exhaust stroke.

So even though both plugs fire together - only one cylinder at a time actually fires.

that can throw you a bit when you're working an ignition problem and see both plugs firing at the same time.

So degree wise....

I'm having a hard time thinking about this for some reason - I'd guess you'd call it 360 degrees between cylinders firing... right?

if each "stroke" is 180.

Cylinder 1 fires into power stroke - cylinder 2 is on intake stroke.

Cylinder 1 then comes up on exhaust stroke while cylinder 2 is on compression stroke

Then 2 fires.

so yeah - fires every full revolution.

(IF it's the same as a tf)

Is is possible even-firing first came when the TJ replaced the TH in 1968?
Wisconsin data on ASECC