H throttle position

Melnick · Jan 18, 2011

I have aquired an H with 12 volts system and magneto. The throttle position must be full off or this thing will not start. This just doesn"t seem right to me. What adjustment(s) are in order?

Also, this tractor is just a bear to start when its cold outside. I normally end up heating the manifold and sparkplugs to get it running. Any help would be appreciated.

Thanks,

Nick

Faster346 · Jan 18, 2011

Is it a bear to start because it turns over slow, or just because it turns over for a long time? I know my 12v tractor won't start with the throttle too low because it wings the engine over so fast.

gene bender · Jan 18, 2011

throttle position shouldnt have anything to do with starting. Remove all plugs hook their wires up make sure they are grounded then hit the starter and observe fire on all of them you can even put your thumb in the hole to see if the spark fires when you feel the compression stroke this will tell you the rotor is in time also. If that checks out your problem then is in the fuel system like sucking air somewhere bad fuel supply carb needs good cleaning and is the gov hooked to the carb correct. Thats why we do the fire first and i checks out you know its fuel.

teddy52food · Jan 18, 2011

Sounds like it needs to have the compression checked & a good tune-up.

James Williams · Jan 18, 2011

A H in good working shape should start in any tempature.

Janicholson · Jan 18, 2011

If the starter spins the engine fast enough the impulse coupling will not engage. It will however not have enough velocity to start well without the impulse.
If it spins over pretty fast, this can be the cause. Shutting the throttle causes it to turn some what harder pulling against a vacuum. (not always)
If it pull starts easily with the throttle at any position, I would suspect this.
A leaky intake manifold is also a possible source of vacuum leak. Some are cracked on the inside of the manifold.
Using a 6 volt battery (and alternator, they are available) or generator, will slow it down if the speed is causing the issue. Jim

Ed Hotaling · Jan 18, 2011

I have an H set up similarly. I find that sometimes it doesn't fire until I let off the starter and the engine slows down enough for the impulse to catch, but that is usually in the summer. as others have said, a good tune-up may help. Also checking the valve clearances might help. Mine was a real bugger to get going (I had to tow it about 1/3 of a mile once!) until I did that. I did several ignition tune-ups and rebuilt the carb with little improvement. Reset the valves (they didn't seem too far off) and she starts in one or two revolutions even after sitting for months.

Allan in NE · Jan 18, 2011

I also vote compression.

A worn engine is hard to start cold, no matter what.

Allan

Melnick · Jan 19, 2011

I do believe the starter is spinning to fast because it fires either as the starter begins to spin or while its slowing down. So,is there a way to slow the starter down or do I change everything back to a 6 volts system?

Janicholson · Jan 19, 2011

6 volt is the simplest. to assess the situation, use a jumper cable about 8ft long with 4gauge wire in it as one of the cables to see if this increased resistance will slow the starter using 12 volts.
If it does, then (short of building a long battary cable to kluge it together) there are two options.
Use a 6 volt battery and convert your alternator (or generator) to 6v.
Have your starter motor converted to 12volt operation. (a newer series delco starter might be retrofitted to the same drive) Good luck. Jim

mkirsch · Jan 19, 2011

(quoted from post at 06:31:31 01/19/11) I do believe the starter is spinning to fast because it fires either as the starter begins to spin or while its slowing down. So,is there a way to slow the starter down or do I change everything back to a 6 volts system?

There is no way to slow down the starter on 12V.

If the engine starts when you let off the starter switch, why don't you just let off the starter switch?

Developing a technique to start it is a lot cheaper and simpler than converting it back to 6V.

The M has an aftermarket high-torque starter on it. Once we converted it over to 12V, it spins so fast the engine won't fire. All we have to do is spool it up with the starter, let off the switch, give it a blip of choke, and it's running. It's really easy once you do it a couple times.

This goes back to learning what the tractor wants to start. It's not a computer fuel injected car that you just turn the key and it runs. It's a crotchety old person that doesn't move so well until it's had its coffee.

Melnick · Feb 6, 2011

Thanks for all your help.

I solved part of the problem. I took the magneto apart and found it was missed timed. I re-timed the magento and now it starts just fine.

I still have to figure out why the throttle has to be closed to get it to start.Icheck the compression next.

Faster346 · Feb 6, 2011

(quoted from post at 17:48:13 02/06/11) Thanks for all your help.

I solved part of the problem. I took the magneto apart and found it was missed timed. I re-timed the magento and now it starts just fine.

I still have to figure out why the throttle has to be closed to get it to start.Icheck the compression next.

A lot of 12v tractors are this way. I'm guessing it's because 12v spins them over so fast that they turn over to quick to fire at a lower throttle position.

H throttle position

Melnick

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Faster346

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gene bender

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teddy52food

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James Williams

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Janicholson

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Ed Hotaling

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Allan in NE

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Melnick

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Janicholson

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mkirsch

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Melnick

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Faster346

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