9N Question...

jctunnelrat · May 2, 2016

Hello All,
I'm new here and not sure if I'm in the correct forum. But... I have a question about a Ford 9n (1946).

Problem: Won't start, sometimes, most every time. But, when it starts runs great, plenty of power.

History: Been fixing this tractor for over 40 years. Complete rebuild in '76 and again in '94. Was a 6 volt positive ground system and recently converted to a 12 volt positive ground system. Now the tractor won't start consistently...

Compression is a little low (80-90 psi average). Compression was in the 60's, did a leak down test and had some bad valve seats/lapped valves brought compression up. Cylinder walls not scored.
Carb has been rebuilt. (twice)
Distributor has been rebuilt. Has good blue spark at plugs (all the time, even when won't start, and fuel)
New distributer installed.
New wires, plugs, electrical wiring.

Weird thing is when I completely cover the carburetor intake with my hand it will pop (sometimes). I was thinking intake leak but I can't find one.

I'd appreciate any advise/suggestions.

Thanks, jim

Tom N MS · May 2, 2016

Just curious-why was it changed over to 12 volts? Did you have the same problem when it was
6 volt.Compression is a little low and could be the reason for its behavior but I'm not
surprised that it runs good once running..

Bruce (VA) · May 2, 2016

12 volt positive ground? You have a generator instead of an alternator?

W/ all that work on the distributor, did you set the timing?

Does the spark jump 1/4" in open air?
75 Tips

cwtech · May 2, 2016

It sounds like the interior of the intake manifold has rusted through, connecting the intake side to the exhaust side.

This creates the vacuum leak which is hard to find. ...Once the leak is large enough, hand choking will not work.

Dell (WA) · May 2, 2016

jim........uh, you do know when you cover yer carbie mouth with yer hand thatza same thing as a using yer carbie choke knobie on the dash panel, don't you? As fer rebuildin' yer carbie (twice) most neiubee shadetree mechanic wannabees make MAJOR mistakes in adjustin' the carbie. Heres how I doo itt. Adjust the down-pointing MAINJET to 2-turns and LEAVITT!!! Adjusting the side-pointing idlemix fer FASTEST idle, NOT SMOOTHEST idle. Understand the difference??? The side-pointing idle mix is BASSACKWARDS, out fer lean, IN fer ENRICH. Usually ends up about 1/8-1/4 turn. As fer yer compression, Ford spec's is 90psi MIN; good runnin' N's about 110psi, new overhauled N-engines about 125psi. .......HTH, the amazed Dell

markct · May 2, 2016

It's not tho, as the choke allows a bit of air past, your hand doesn't

JMOR · May 2, 2016

(quoted from post at 13:22:10 05/02/16) It's not tho, as the choke allows a bit of air past, your hand doesn't

.......and the 'hand' also closes off the bowl vent where choke butterfly does not.

HFJ · May 2, 2016

welcome to YT, JC

just so u know - 1946 = 2N. all 9N and 2N serial numbers start with 9N.

Hobo,NC · May 3, 2016

The color of the spark means nuttin... Forget all you have ever read about color equals good spark...

What I have to say about color of spark...

http://forums.yesterdaystractors.com/viewtopic.php?t=1264328&highlight=color+colour

jctunnelrat · May 8, 2016

Thank you all for your advise. Has any body ever done a 6 v. to 12 v. conversion? The conversion was not my idea and I'm at loss for fixing this thing.

Royse · May 8, 2016

Of course we have done 12V conversions.
Most of us have done many of them.
I doubt that is your problem unless you have had this
problem ever since the conversion was done.

If you have though, what coil do you have? 6V or 12V?
What resistors do you have in series with the coil?

If typing isn't your thing, shoot me an email and I'll
send you my phone number so I can help over the phone.
[email protected]

9N Question...

jctunnelrat

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Tom N MS

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Bruce (VA)

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cwtech

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Dell (WA)

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markct

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JMOR

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HFJ

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Hobo,NC

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jctunnelrat

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Royse

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