Electronic Fuel Injection

As Steve said... cleaning up the carb, and having a hot magneto is the easiest, and simplest solution...

Inverting a throttle body onto a carbeuration-intended manifold gives away basically all the benefits of EFI... it will be raining fuel down into the filter elbow.

Remember- the intake manifold is heated, for the purpose of atomizing fuel droplets coming up from the throttle body.  When one moves the injectors to the ports, there is no need for a venturi, thus, there's substantially less temperature change forced into the intake manifold, thus, it is less susceptible to buildup of frost in the intake.

IMO, the best system, is just a carbeurator and a magneto, as you will NEVER need to worry about a dead battery, in order to get your machine alive.  NONE of my emergency generators have fuel injection or distributors- they're all magnetos and (propane) gaseous mixers... operated by gravity and thermal expansion... no batteries required.

And Joe, you mean all ALLIS 4 cylinder engines fire the same pattern 1-2-4-3 .... I think there are some companies that 1-3-4-2 .......... "Normally" you have pistons 1 and 4 separated by 2 and 3 in the FIRE order... but that can be mixed.

and a CAR normally works different than a TRACTOR on two items.. One is the motor normally turns a faster RPM on a car... and the car has a DOWN DRAFT carburetor, where most tractors have an UP DRAFT carburetor...

Mist is not atomized... it is small droplets.  Droplets are NOT evaporated, and liquid fuels don't burn, and they don't defy gravity.   The black stuff you see on your tractor's stack, is liquid gasoline, that came out the exhaust, because it was not evaporated PRIOR to ignition.  Compare that to a gaseous fuel engine (propane or natural gas), you won't see it, because those fuels don't need evaporation prior to being introduced to oxygen, they simply need to be well-stirred with oxygen, and sent into the chamber.

Zora Arkus-Duntov wrote some wonderful white papers on airflow velocity, pulses, and evaporation, and explained not only how his plenum designs counteracted the 5-7 cylinder 'shared port' limitations, he also demonstrated how the manifold exhaust bypass flow provided heat to greatly reduce droplets forming downstream of the carbeurator flange.  He's credited with some wonderful things, but they weren't necessarily HIS revelations.  Allis engineers were brilliant in their choice of firing order... had they used the same order as MOST other manufacturers, they would have had assymetrical pulses between neighboring cylinders.  If you're an audiophile, and you listen to a hundred four-cylinder engines at idle, you'll be able to identify the Allis's alteration, because the timing of pulses front-to-rear get a more consistent fuel charge between all cylinders... they don't have two running light, and two running heavy.

You miscalculated pulses, Steve- it's a four-stroke, so four firing events per TWO revolutions.  With regard to frequency and smoothing, an Allis running at 1500rpm is making 3000 firing events per minute.... that's 50 per second... 50hz.

The pulses you get from that, are what fluid dynamics guys refer to as 'audio frequency'... meaning, you can HEAR it.  The hum you hear from a home appliance transformer, is 120hz (you hear the first harmonic)... that's a 'low bass' note.  (A above Middle C on a piano is 440hz)

HALF of those pulses are going to the rear two cylinders, the other half are to the front, that means 25 per second to the rear, 25 front.

This is NOT by any measure 'fast'.  12.5hz per cylinder, is slow.

Now slide it down to 500rpm, as the injector will HAVE to operate there...

That's 8.3 revolutions per second, or 4.15 full cycles per second.  Each cylinder is firing on one-second intervals... and amidst that timeframe, the intake valve is only open for a small fraction of angular rotation.  The airflow inside the intake, at this point in time, is absolutely NOT constant.

But an easy way to illustrate-  take the lid off a TBI vehicle.  Start the engine, watch it idle.  Look at the throttle plate (it's closed).  See all that fuel spray... hit the throttle plate, and then cascade down into the intake like a waterfall.  With the throttle body inverted, it will literally fall OUT at low airflow rates.

Here's some really good history on the earliest mass-produced fuel injection systems: