# Little Video of a pony start 720 diesel



## Soldier Tom (Sep 25, 2004)

I thought I'd invite yall to my barn for a few moments. 
Hope you enjoy it.
http://s147.photobucket.com/albums/r292/SoldierTom/?action=view&current=Startsequence3.flv


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## John-in-Ga (Sep 22, 2003)

Those pony motors really whine. Yours doesn't even smoke!!! What few I've seen did.

I played both your videos. Enjoyed them both.

Great looking 720.

Thanks for sharning.


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## Archdean (Jul 15, 2004)

And I too enjoyed the visit Tom! Nice looking 720 but I'm more familiar with the letter series, can you rank it for me please, HP/years made and etc!!

P.S. Nice to see someone else provide that kind of video presentation, it is a great way for all of us to share with each other!

Dean


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## Soldier Tom (Sep 25, 2004)

I am glad yall liked the videos. I could sit and watch that kind of stuff all day. I wish more folks would post videos, threashin, balein hay, cuttin hay, what ever...
Dean, 720 is the direct decendant of the venerable G. G begat 70, 70 begat 720, 720 begat 730 then into the new generation 4 and 6 cylinder I kind of loose count after that. This one was shipped out to Lamar MO in Nov of 56. I found it in Nashville TN and traced it back through Lincoln, Nebraska to "somebody in South Dakota" where it was sold at a farm auction. Don't know who originally owned it or where it spent most of its workin days between 1956 and 2000. I think it was around 50something hp, but I don't recall exactly.
John, that is at least the second pony that tractor has had. The one that was on it when I got it would run about 1/2 way and smoke like a tar kiln, it would barely roll the diesel at decompression and if diesel didn't hit on the second roll, it died. Took it off and found that at some point way back when, it had "eaten" two cylinders, connecting rods and all, nothing left but chuncks of 'luminum. Steve at C&L tractor found this motor out of the mid-west somewhere and got it for us. We rebuilt the carb, and replaced the water pump impeller and seals about 3 years ago. The diesel is really tired, spits black ooo all over everything. Needs to be rebuilt, maybe this summer I can get ahold of that. Oh if only money was not object....
That is about the story...
Walk in peace
Soldier Tom


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## John-in-Ga (Sep 22, 2003)

Amazing that your first pony with two pistons gone would start your 720. They sure don’t make’em like they used to.

The question I’m about to ask usually gets the “get a manual” response on most boards. I’ll probably never own a tractor with a pony, so getting a manual seems a little foolish. Pony starts intrigues me, however, so here goes…. 

Could you explain in a little more detail how a pony motor is used to start a tractor? 

Maybe, at least, you can correct what I have wrong in the following:

If I’m not mistaken the V4 pony is suppose to idle at about 4000 rpms. Fully revved up runs at about 5000 rpm. It uses gasoline for fuel and is started with an electric starter.

You start the pony and let it warm up the diesel motor. Which it will do because it circulates the coolant it shares with the diesel through the diesel’s block??? 

Once the diesel is warm you engage the pony and let it turn the diesel over until the oil pressure comes up??? 

At that point you activate the compression lever???? This allows the diesel motor to develop compression. 

Once the diesel motor cranks, the pony is shut down by shutting off the fuel to it???

One must also remember to open the electrical circuit feeding the ignition on the pony to keep from burning out the coils in the ignition circuit on the pony????


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## Soldier Tom (Sep 25, 2004)

*Pony Starting*

John, you have a pretty good handle on that. The pony (cranking engine) was used for diesel cranking in days before strong batteries and "pure" diesel. The 6 volt battery easily enough started a little 18 hp V4. It did circulate coolant through the block to warm it, it also blew exhaust around a hollow in the air intake manifold to pre-heat the air coming into the combustion chamber. After several minutes (book says 5-10 or until block is warm to the touch) you begin the start sequence. Idle up the pony to "run" (5Krpm).
The 720 and 730 had three levers to work with to start. There are two that operate the pony and one for fuel. The outside lever engaged the flywheel and spun the diesel engine. The inside lever opened the exhaust valves to prevent compression in the cylinder. 
First pull both levers to the rear: This would "motor" the diesel engine over several turns with no compression. This allowed the engine to free up some and "get the juices flowing". 
Release the inside lever: This allows the engine to turn over on full compression, and also builds up oil pressure; when you see oil pressure reading on the guage, you know the engine has been pre-lubed.
Advance the throttle off of stop: This "turns on the fuel" and the diesel engine thumps to life hopefully.
When the engine cranks, release the other handle and turn off the fuel to the pony. When it dies, turn off the ignition switch. The 730s and later 720s had a cut off that broke current to the points when oil pressure fell below a certain point. (Mine don't have that). 
That is, in a nutshell, how it works. To start it properly from a cold start took every bit of 10 minutes on cold mornings.
Hope that helped!
~Walk in peace~
Soldier Tom


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## Archdean (Jul 15, 2004)

Question to you two Deere guys?

My Brother had a "G" and I only drove it once before he traded it on something An Allis I think!

Any way I dont believe it had a pony motor and I'm certain it didn't, is this something added later?

What it did have was a lot of torque and when I loaded it on his trailer for him I soon found out why he wanted to trade it!! 

That ole girl is a hand full and as a boy I can remember an accident with a neighbor (had John Deeres, we had Farmalls) A 'G' rolled over backwards , to be fair though we farmed in mountainous country!!

Any way his damn near did the same thing when I tried to coax her up on the trailer, she finially relented when he put a winch on her nose and it made me feel better too! That was the last time I was around one and as some of you know I have put a thing or two on a trailer!!

Just for grins: 
<img src="http://img.photobucket.com/albums/v517/Archdean/bigTractors004Medium.jpg">

:cowboy:


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## Soldier Tom (Sep 25, 2004)

The G's were never offered in diesel. That all started on the later 70s. The R's were diesel and used the same general setup with the cranking engine. Started out with a 2 cylinder gas engine started with a pull string if the bat'ry went dead. Then the V4 setup proved better.
I do admit the 2 cylinders were not very nose heavy and do tend to rare up on you from time to time.
Looks like you put a LOT of things on trailers John!


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## John-in-Ga (Sep 22, 2003)

*Soldier Tom,*

Thanks for the finer points. Think I got them. Can I come up and practice what I know about pony motors by starting your 720?  


*Dean,*

If I’m not mistaken some of those old Gs were hand cranked. Open the throttle a little, crack the choke, grab the fly wheel and flip it over. The G is running.  Not that I’ve ever done it. Looks easy at the shows. 

Feller was killed loading his 2 cylinder after a show last year. I wasn’t at the show. Experienced people who were, agreed that if he had backed on the trailer the accident would never have happened.


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## Archdean (Jul 15, 2004)

John,

"Experienced people who were, agreed that if he had backed on the trailer the accident would never have happened."


I agree maybe~~~ I tried that first and my brothers trailer is a hi-bed duel tandem trailer not as low as the one I showed you in the above picture...The problem occurred because the draw bar would not clear the trailer frame at the top of the ramps!! That's why I went nose first and used a winch to hold her nose down!! BTW before I left Kubota I had one put on that trailer as The "G" wasn't the only snot buster I encountered!

As far as being experienced in doing such things I probably just might qualify!!


:cowboy:


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## Thomas (Nov 1, 2006)

Gotta love that sound,for we know what lays ahead:tractorsm


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## Soldier Tom (Sep 25, 2004)

There was a LOT of the 2 bangers hand started. Yes, sir. I am lookin through my videos to see if I can find one. I think I had one of a fella starting a D by hand. We had an A for a while that started that way, and you killed it by shutting off the fuel and waiting for it to run out of the carb. There is a trick to that, admitedly I do not know it. I've heard my dad talk about spinning the neighbor farmer's G to start it. He said that it could get mighty quirky as far as fuel setting, flywheel position, position of the moon and alignment of the stars, etc. 
I think I credited John with something Archdean did a while ago, the trailer loading, didn't intend to slight you there neighbor.
As far as practicing pony start proceedures, I live off I-40 at the 412 exit. Prob'ly a good road trip isn't it? Im thinkin Knoxville is about 3 hours out of Atlanta, I'm 30 miles east of there. 
Hey! after we practice starting it up, you want to; we could tear into the motor and rebuild it so it stops spitting that black goop all over me when I use it! What do ya say? That shouldn't take too long (should it?) 
I better get back to work, take care now
army 
Walk in peace!


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## John-in-Ga (Sep 22, 2003)

Soldier Tom,

I saw a young lady hand start a D once. It was her tractor and she was nonchalant when she said she did it all the time.

From what I’ve been able to learn about the hand starts, they are “quirky”, but once you learned their “sweet spot” (each tractor is different) and everything is well maintained they will usually start without too much cussing.

You are most gracious in inviting me up to help overhaul your engine and there is nothing I’d like more. However, I saving ever penny I can right now in order to have the money to rebuild the transmission on my 51 B. Financing a 350 mi trip to Knoxville just to have fun is, at the moment, pretty much out of the question. I’ll not forget the offer and, if by some miracle, I win the lottery, you can look fer me and my B to show up. We’ll probably have to pull start your 720 first couple of times we start it after the rebuild.


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## HYDROGUARDIAN16 (Feb 14, 2007)

im not a big tractor guy yet but I love looking at them. why does it sound so loud in the beggining of the movie? is that the starter im hearing? it must be because for something that big i am not sure it would fire up by handcranking. please give me some info on how you start this beast.


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## Soldier Tom (Sep 25, 2004)

*How it's done*

Hydroguardian16;
That is indeed the cranking engine (pony motor, pup motor) you hear at the first of the video. 
Up in this thread is a good couple of responses as to the particulars of the starting a diesel with a pony. 
Basicly, tho, you start the little four cylinder motor and let it warm up the whole system a few minutes then you engage the cranking engine and it rolls the diesel over until it starts.
I understand this same kind of system was used on the big Caterpiller dozers. Great system for the technology of the day. Good today too, takes a minute to get going, enforces patience and whatnot.
Glad you enjoyed the video!

~Walk in peace~
army


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