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John deere 2 cylinders firing timing

F

FSten

New User
Why did the engineers at john Deere set the compression timing to follow right after another? why wouldn't they space them out evenly? The only
reasons i can think of is starting in the cold as they might need a little extra push to get to the next firing round, and the carburetor might be
able to animate the gas slightly better for the right hand cylinder if the left cylinder had just "primed" the carburetor so the right cylinder can
hit harder
 
It's not something the engineers "chose" to do, that's just how it works out with a two cylinder engine with 180? offset crank throws.

Alternative to make it fire evenly would require the two pistons to move together (that was done with some two cylinder Wisconsin engines, as an example), but that would create a balance nightmare!
 
I saw an A years ago at the Portersville, Pa. show that sounded way different. Owner said he cut the crank and welded it back with a huge counterweight. Camshaft, too.
 
Having two heavy pistons the balance works best if when one piston is at TDC the other is 180 opposite at Top dead Bottom. Many don't realize that the pop pop pop pop you hear from a Johnny Popper is NOT left firing POP and right firing POP 180 later, the POP the human ear can recognize is the COMBINATION/ADDITION of BOTH firings (a quick 180 apart) followed by the relatively longer 540 degree coast cycle before the ear detects another POP. You don't hear POP POP then ---- ----- ---- (540 degrees). The late Duane Larson a Nuclear Physicist wrote an in depth article on that subject I may have it somewhere.

John T
 
The POP POP is every other revolution and if you listen close it's a double POP. You really notice it if there's a misfire on one side. Please post that article if you can, I'd like to read it.
 
You?re right, John T ? with a 180 degree offset crankshaft (one piston top, other piston bottom) on our 4-cycle JD engines, one cylinder is going ?PUTT ----- ----- ----- ? during the four-cycle piston movements, and the other cylinder is simultaneously going ? ---- PUTT ---- -----". The ?putt? one hears is on the exhaust stroke, so when listening to the engine, you would expect to hear ?PUTT-PUTT ---- ----?. But Duane Larson pointed out that the valve timing on our two-cylinder tractors is such that there is an overlap where both exhaust valves are open during their respective exhaust strokes. So instead of hearing two distinctive ?PUTT-PUTT? sounds, we actually are hearing a longer, drawn-out ?PPUUUUTTTTT? as both exhaust sounds overlap. Of course, as you know, at a really slow idle, you can hear the individual exhaust sounds, but you really can?t when the engine is running fast.
 
The long pop can be verified by someone dumb like me by shorting out a plug at about 1/2 throttle. The governor will keep the engine speed the same and the rhythm of the pops will be the same, but they will be softer. I did this by accident once, leaves quite a tingle in your finger for awhile. . . If you want, you can use a screwdriver instead.
 
(quoted from post at 21:21:41 04/09/19) Why did the engineers at john Deere set the compression timing to follow right after another? why wouldn't they space them out evenly? The only
reasons i can think of is starting in the cold as they might need a little extra push to get to the next firing round, and the carburetor might be
able to animate the gas slightly better for the right hand cylinder if the left cylinder had just "primed" the carburetor so the right cylinder can
hit harder
Click to expand...

They originally wanted them to sound like Harleys, however there was not sufficient room in the design for a V-twin engine. The closest they could come up with is what we are all familiar with.
 
(quoted from post at 12:45:22 04/10/19)

They originally wanted them to sound like Harleys, however there was not sufficient room in the design for a V-twin engine. The closest they could come up with is what we are all familiar with.
Click to expand...

I hope that this was just in fun because that's not quite how it happened. There were a host of reasons why the engineers at JD decided on the horizontal twin, among them were reliability, operator view and fuel economy.
 
To get an in depth analysis of the John Deere Two Cylinder Firing Order and the sound the human ear recognizes POP POP POP POP and why that's so, you have to get a copy of:

The following article was written by Duane Larson for the December 2002 Issue of the East Tennessee Two-Cylinder Club Newsletter

" Analysis of the Firing Order and Sound of a John Deere Engine
By Duane Larson"

The website may be a source, I have all his publications in PDF Format but not sure if I can copy n paste some here, I will take a look.

https://jd2cylservice.com/

John T
Duane Larson Website
 
(quoted from post at 21:10:19 04/10/19)
(quoted from post at 12:45:22 04/10/19)

They originally wanted them to sound like Harleys, however there was not sufficient room in the design for a V-twin engine. The closest they could come up with is what we are all familiar with.
Click to expand...

I hope that this was just in fun because that's not quite how it happened. There were a host of reasons why the engineers at JD decided on the horizontal twin, among them were reliability, operator view and fuel economy.
Click to expand...

Definitely in fun.

The reason the letter series had a 2-cylinder is because it was inherited from the Waterloo Boy and it was the fastest/cheapest to develop. Why did they go with a 2 cylinder in a the Waterloo Boy? I don't know...probably inherited that design from steam engines?

If Deere has been good at anything, it is marketing.
 
Keith Merfeld in Peosta Iowa did one and he showed me it running. It did run different and was band at a lot of pulls because it pulled good. I was told he sold it to some guys in South Dakota and they teak it and was very good at pulling. The kid built parts for my 37 a and he told me that now I can pull in the 4500 pound class and spin out. I had to try it and he was right and I was on a every good track and beat up on a lot of tractors. Had to turn up the built carb for it because it was starving for fuel and in the 5500 it would pull it in 3 and spin out. I was very happy with his work it took some time to get it all done but and the end it was worth it. I also heard he move because his brother was building parts in the shop and things were going bad there.
 
I have wondered how a two cylinder would sound if we changed the firing order to 2-1 instead if 1-2. When 1 fires, it takes longer for the exhaust to exit the manifold and 2 fires very quickly after but has a shorted distance to travel to exit the manifold. Thus it sounds much like a single cylinder. I believe if we fire 2 first, the sound would exit quickly and the sound from 1 would be delayed due to the distance traveled. We might get a two cylinder sound. Just chop the cam in half, weld it up and go. I would do it myself if I win the lottery.
 
(quoted from post at 12:16:58 04/11/19) I have wondered how a two cylinder would sound if we changed the firing order to 2-1 instead if 1-2. When 1 fires, it takes longer for the exhaust to exit the manifold and 2 fires very quickly after but has a shorted distance to travel to exit the manifold. Thus it sounds much like a single cylinder. I believe if we fire 2 first, the sound would exit quickly and the sound from 1 would be delayed due to the distance traveled. We might get a two cylinder sound. Just chop the cam in half, weld it up and go. I would do it myself if I win the lottery.
Click to expand...

Oh, LORD!
 
(quoted from post at 12:16:58 04/11/19) I have wondered how a two cylinder would sound if we changed the firing order to 2-1 instead if 1-2. When 1 fires, it takes longer for the exhaust to exit the manifold and 2 fires very quickly after but has a shorted distance to travel to exit the manifold. Thus it sounds much like a single cylinder. I believe if we fire 2 first, the sound would exit quickly and the sound from 1 would be delayed due to the distance traveled. We might get a two cylinder sound. Just chop the cam in half, weld it up and go. I would do it myself if I win the lottery.
Click to expand...

Just build a dual exhaust pipe setup and make #1 way longer. See if you can get it to sound different.
 
# 1 reason was balance while one piston-rod combo is going up one is going down kind of cancelling each other out. if both assemblies moved together there would be a tremendous amount of counter balance on both ends of crankshaft.
#2 reason would be crankcase venting again one piston going up one going down not a lot of pressure built up in in crankcase . if both pistons went up and down together you get positive then negative pressure in crankcase oil pushed out dirt drawn in.Paul
 
i just realized how dumb a question this was after i sat down with a little inline 4 model and covered 2 of the cylinders not sure why i couldnt think through this without the model
 
(quoted from post at 16:23:26 04/11/19) i just realized how dumb a question this was after i sat down with a little inline 4 model and covered 2 of the cylinders not sure why i couldnt think through this without the model
Click to expand...

'Ya done GOOD. Nothing like a little "hands on" to help understand how things work!
 
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