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4 cylinder runs, sounds like 2 cylinder

1

1954Frank

Member
Maybe I'm crazy: a few weeks ago I read a forum discussion about modifying a 4 cylinder tractor to run like a 2 cylinder. 1 and 4 fire simultaneously, then 180 degrees later 2 and 3 fire together. 540 degrees (1 1/2 revolutions) later the cycle starts again. It yields a sound/cadence similar to a 2 cylinder JD.
One of the persons posting explained how he accomplished this. I have thought on this at length, and searched these forums with every key word I could think of, but came up empty. I would like to read this discussion again. It seems extensive changes to the valve and ignition timing would have to be made.

Maybe it was on farmallcub.com.

Anybody recall/know about this? Thanks.
 
A Farmall Cub is pretty short on power when it's hitting on all 4 normally, that would really make it useless! I have driven 2
cylinder JD's and Farmalls, and I much prefer the sound of a Farmall.
 
It is possible. The cam shaft would need to be cut and rewelded (very straight and precision machine work) so the 1-4 valve
timing is the same, and 2-3 timing also re clocked. Three cuts would be needed in the cam to make this happen. The timing would
be such that 1 and 4 would fire together, then 2 and 3 would fire together, but like a JD it would be put-put, pause-pause.
Ignition would be easier in that a single electronic trigger could be used to switch 2 cylinders at once. Some electronic
fiddling would be needed. A JD distributor, and electronic trigger?
Problems would be really nasty impulse over stressing of the crankshaft. Especially at the 3-4 area as 3 and 3 twisted on the #4
journal and at the rear main when 1 and 4 fire together. Twice the cam shaft loading is also happening as the cam opens 2 valves
every time the lobes come around.
Clutch stress and drive line stress would also be an issue to contend with. Doubling the torque instantaneously on the
components is not wise. Intake systems and exhaust are designed to handle flow for one intake per 90 degrees. Not twice the
amount, as would happen when 2 cylinders sucked air/fuel at once, and two exhausted at once.
Much easier to ground #4 and #2 plug wires, and remove the rockers on them. Jim
 
it may not have a heavy enough flywheel to
carry it through 2 cylinders on
compression. I think you will be looking at
a broken crankshaft before too long.

Ben
 
Why on Earth would anyone want their Farmall to sound like a JD? I'd just pull two plug wires for a short
time then replace them quick before anyone hears it.
 
Some of the Triumph riders did that on their flat track bikes for more torque out of the corners.
Of course they only had 2 cylinders, but the same idea.
 
What you are wanting it to do is make it a flat crank design (the Ford V8 Sherman tank engine is the same way, two cylinders firing at once making it sound like a 4 cylinder). Problem is it will vibrate like crazy, even the Ford V8 tank engine vibrates, and their is no way to get the vibration completely out of it. With a 4 cylinder engine the vibration will be even worse, it's not worth it. If you want something that sounds like a poppin johnny, buy a poppin johnny!
 
Are we talking custom camshafts here, or using production parts? If the original cam is ground for 1 to fire 180 degrees from #4, then radical changes have to be made.

I recall Smokey Unick said in his 'performance secrets' book that he experimented with flat cranks in small block Chevy engines. He said he couldn't get them to make more horsepower, but they 'sounded sweet'. So I guess if the sound is what you are after, go for it.
 
Sorry I didn't see the discussion.

But I think if I were going to try to do this, I would forget the cam and and remove the cylinder 3 and 4 push rods on an overhead valve engine. Then build a bridge between rockers for cylinders 2 and three so cylinder 2 intake would open cylinder 3 intake and cylinder 2 exhaust would open cylinder 3 exhaust.

Then I would modify the rocker shaft so it is free to rotate, and consists of a shaft in a shaft. The internal hollow shaft should be fixed to cylinder 1 and 4 exhaust valves, and the external shaft is fixed to cylinders 1 and 4 intake valves. You might want to reinforce the push rods but for no more hours and low speeds you should be running it, the cam, lifters, and push rods should handle the load.

If you were going to try to modify the cam I think I'd get two cams and put another front section under 3 and 4, and instead of welding together, come up with a coupling type joint so each shaft can self align. Then all you have to do is regrind the rear shaft bearing journals.
 
Interesting that the exhaust manifold for a four cylinder would be OK, since 1 and 4 are through separate exhaust passages, 2 and 3 are also usually separated. Intake manifold would be the same, flow to 1 and 4 are separate passages, as are 2 and 3. The carburetor would be undersized but you might get around that by dropping the carburetor and putting an expansion chamber above it (for a Farmall letter series) to help dampen the pulsations through the carburetor. You want a bigger muffler/pipe to magnify the sound anyway.
 
They did something like that with Honda 305s. Made a "twingle" out of 'em.had to bump
start 'em,starter pawl wouldn't take the force
 
It's a whole lots simpler than you-all are making it out to be. I have a 4000 4-cylinder Ford that I have
achieved the 2 cylinder putt putt sound of a John Deere. I'm still working on my project and I'll share it with you when I'm finished..it may be a couple of months.
Jim
 
Thanks for all responses. I didn t say I wanted to do it. I read about it somewhere and I m trying to understand it. I thought it was in a discussion on YT. Probably on another forum.
 
Years ago I met an old fellow that had a JD B and he was in the process of making it fire like other engines do ? I did not hear it run as I don't think it was done yet ? I figured if it was going to gain anything like power or fuel efficiency JD would of figured it out and done it.
 
(quoted from post at 10:34:19 08/02/19) Years ago I met an old fellow that had a JD B and he was in the process of making it fire like other engines do ? I did not hear it run as I don't think it was done yet ? I figured if it was going to gain anything like power or fuel efficiency JD would of figured it out and done it.
Click to expand...

I have heard one of those Bs run. Sounded an awful lot like my old Honda CL 350.
 
Why not sell your 4 banger and put little more
money with it and buy a good 2 cylinder john
deere?
 
The original Farmall Cub conversion was part of some other custom work, a tricycle cub, being done. Despite what was said, the Cub clutch, drive line, camshaft, carburetor, and crankshaft are more than strong enough or large enough for the 4 cylinder to 2 duel cylinder conversion. The horsepower will not be significantly larger or smaller although the torque curve will likely change.

The camshaft was cut in half at the center bearing and rotated. Just one cut not 3. There are custom camshaft folks that could also have made the camshaft. The ignition system was composed of 2 duel spark motorcycle coils,each firing 2 cylinders at the same time. Three of the 4 distributor lobes were ground smooth and the remaining lobe opened and closed the points. An additional set of points was added 90 degrees from the original set. One set of points went to one coil which fired pistons 1,4. The second set of points went to the second coil and fired pistons 2,3. The rotor etc... was not needed.

I don't think anyone doing this type of conversion believes it will result in a pot of gold at the end of all the rainbows in the world nor will it place the bluebird of happiness on everyone's shoulder, it is just something interesting to do, for those that like the sound of a 4 cylinder engine then don't do the conversion. It is just a tractor engine not a cure for cancer.
 
Thanks electro. That's a good explanation that I can understand. I will search farmallcub.com for the discussion that I saw earlier. Thanks for all responses.
 
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