OEM Resistor

MM in SC

Member
Hey guys,
My wife got herself a 1949 8N with a 12 volt conversion.
( Gotta love a woman like that!) Anyway, she has known about the tractor for several years. It has new tires on back, engine rebuild, ran great, no issues there. Before she got the tractor, the guy converted it to 12 volts with alternator. He installed Pertronix ignition and alternator. Not much luck getting it to run after that. it will kick off, but not continue to run.
I have been reading a lot of previous posts about issue. Here's what I have
2.5 ohms at coil.
12.8 volts to coil
Copper cored spark plug wires
Took bolt out of bottom of carb bowl fuel poured out.
Used inline spark plug tester so I could see the spark. Spark looked orange and not white or blue.

Still tracking down problems using meter and will jump start switch. As I was looking to do that, I started checking wires on the OEM resistor. The single lug on the bottom is loose and I can wiggle it a good bit. My question is, is that normal?
Thanks
 
Spark plug test does very little. Try hot wiring it as in run a wire from the battery to the top of the coil and try to start it. If it starts and runs that way your problem is from the battery back if it still does not run and has a blue/white spark that jumps a 1/4 inch gap or more you may have a clogged up carb
 
(quoted from post at 18:24:07 09/14/14) Spark plug test does very little. Try hot wiring it as in run a wire from the battery to the top of the coil and try to start it. If it starts and runs that way your problem is from the battery back if it still does not run and has a blue/white spark that jumps a 1/4 inch gap or more you may have a clogged up carb

Did as you suggested. I have good spark and put plug back in. It would catch, but not run. The starter does spin out. I guess I need to rebuild it. The battery is about 580 CCA's.
Fuel sat in the tank and carb for over a year, so I guess I'll rebuild it as well.
Thanks
 
Old gas is not good since it absorbs water from the air due to the alcohol in it.
 
(reply to post at 10:15:47 09/14/14)

What kind of inline spark tester are you using :?: ... if its not a adjustable one that has a scale on it to show the KV what you see is of no use... This is why you see post like this go on and on and on page after page....
 
so lets recap.

ran great befor ethe EI install.. hmm.

got the old breaker plate with points on it to swap back in and see if it runs?

post back.
 

I ran across a EI front mount that sounds zackly as his... I fell off the wagon and used my judgment on the spark it sparked :evil:
I installed a points dist it ran :shock:

OK now I had to confirm EI was switching nuttin to it EZ as pie it did WTF.... I drug out my spark tester spark was weak would not fire @ 20KV GRRRRRR!

I installed a new 12V square can coil and a OEM resistor (No resistor was on it when it came to me).... It purred...

Spark will fool the best use a spark tester that will gauge it....
 
I'm not sure what transistor the common EI's use to switch, but my guess is it is either not a mossfet, or the junction has much more resistance than closed points do. Either should be fine to make 8kv or so however.

Other failures could be magnets slung out so not triggering reluctor.
 
(quoted from post at 16:56:19 09/15/14) so lets recap.

ran great befor ethe EI install.. hmm.

got the old breaker plate with points on it to swap back in and see if it runs?

post back.

I did put the points back in and used the meter to check for gound. Everything checked fine. Timing set. POints not pitted.No spark at all. New to 8N's. DId not check capacitor. Not sure how.
I am leaning towards the carb as I can see " stuff" floating in bowl, but I am open to all suggetions.
 

What kind of spark tester did you use to confirm spark... In line means nuttin to me,,, confirm that... If you can not confirm known good spark No one can help its all a guess...
 
sorry, your logic is faulty.

no amount of carb problems will prevent spark.

lets VERIFY spark before we start worring about gas in carb and air in tires and other things..
 
Automotive Ignition Systems. 1st ed. New York: McGraw Hill : 6kv


Small Gas Engines. South Holland, IL: GoodHeart Willcox : 6kv up to 20kv

of course, atmospheric pressure and makeup and shape of the electrodes do influence the voltage at which the arc can jump the gap.

what do your diagnostic spark analyzers show on the common .025 spark gap voltage buildup before arc?

I have worked with a guy that had a picoscope system that graphed on the pc, and the last one we ever played with arced at 14kv.. but that wasn't a tractor engine.. nor a .025 spark gap. it was a higher compression engine at had .04 gap
 
(quoted from post at 20:08:46 09/15/14)
What kind of spark tester did you use to confirm spark... In line means nuttin to me,,, confirm that... If you can not confirm known good spark No one can help its all a guess...

Understand. It's just a tester that shows if it is firing. I took out plug and opened gap to close to 1/4"
It sparked but did seem to be pretty thin
It was white I don't have access to any other sort of plug tester
 

If all the stars in the universe lined up and you could spin the engine over fast enuff it may fire off if you were lucky...

He will need a coil that will max out to fire it off... 8K is not gonna cut it on a cold start cranking speed only... It will run as you have witnessed at 8K but will stumble and fall on its arse if you load the engine if that's all the coil will do....
 
(quoted from post at 20:23:08 09/15/14) sorry, your logic is faulty.

no amount of carb problems will prevent spark.

lets VERIFY spark before we start worring about gas in carb and air in tires and other things..

I do have spark and ignition with EI- it just will not continue to run
 
IF the coil was limited to only be able to make 8kv ( bad insulation, or anemic secondary) then yeah id agree, an 8k max wouldn't give you any wiggle too at all. Ideally your coil would have the capacity/ ability to let you open up the spark plug gap ip till you hit dwell / charging issues anyway. I for sure agree with that.
 

Correct. That was in response to taking out EI and putting points back in. Original post was it will fire but not continue running. I have taken Hobo's advice and ordered a testor that will show volts. Could well be that spark is not hot enough. In a couple of days, I'll have the real numbers
 
What spark bolo are you getting?

Is it random, or serial?

Will it fire max effective gap open air?

Can you keep it running on start fluid?
 
Sorry not sure what you mean by " spark bolo"
Ether will not keep i t going
It will fire open air over less than 1/4 gap, but pretty thin.
it seemed to be serial, but really my eyes arent that good
 
I type on a phone, it randomly pics words out of my text and helps me by changing them to completely different words, like bolo instead of color.

Not running on ether tells me you still have spark issues, ether flashes off very easily, anything jumping the gap should make it pop...
 
Don't you hate it when the phone thinks its smarter than you?
Of course, in my case it might be true!
The spark looks white. I'm just going to put it on hold till the tester gets here so I can measure volts
 
" The spark looks white. I'm just going to put it on hold till the tester gets here so I can measure volts"

What kind of spark checker are you getting that measures volts?

I've only seen two for "home use"....the worthless ones w/ a light & the good ones that allow you to adjust the gap......as in the two links that Hobo attached previously.
75 Tips
 
OK. I got my Lisle tester and put it on per instructions .
I got a regular spark at times, but then it went random. Also, I could open the spark gap up and get a longer spark than I could get trying to turn it back down after I had stopped.
The widest I could get was between the S and the E
Sooooo, even though the coil is new, I"m guessing the coil is the problem?
To recap , everything was replaced by previous owner.
Cap, rotor, EI, Plugs, coil and I added copper core wires.
a169169.jpg
 
" I"m guessing the coil is the problem?"

Don't be in such a hurry to replace parts.

The first rule in troubleshooting is to start w/ the most likely cause & work to the least likely cause.

A square coil giving an intermittent spark when cold is unlikely.

The most likely source of the problem?

A weak battery.

Followed by poor grounds.

First, charge the battery. (see tip # 60)

You need a strong battery to:

1. Close the solenoid

2. Spin the starter

3. Engage the bendix

4. Provide voltage to the coil.

As the battery gets weaker, the first thing to fail is your spark. If the battery is almost totally dead, all you will hear is the solenoid clicking.

In addition to charging the battery, chances are you need new cables as well (tip # 41). And, don't forget to clean all the grounds, to include the mating area between the starter & the block.

The more current you use to spin the starter, the less you have for the ignition.

After the battery is fully charged, check it per tip # 49.

Then, check for battery voltage at the top of the coil.

If you do not have battery voltage at the top of the coil, run a jumper wire from the battery directly to the coil & see what happens.

Post back w/ results.
75 Tips
 
Thanks Bruce. I'll check all my grounds and make sure the battery is charged and measure volts. The spark coil is wired directly to battery now. Also the starter is spinning out after the engine " catches" Needs rebuilding?
Finally, how wide of a gap on my tester should the spark be able to jump?
 
" and measure volts."

Unless the battery is stone cold dead, that won't tell you much. Current starts the tractor, not volts. See tip # 49 to check the battery.

" Also the starter is spinning out after the engine " catches" Needs rebuilding?"

Again, odds are the answer is no.

You can get the newer style bendix or you can do a tune up on the tractor.

It works like this......the bendix engages the ring gear on the flywheel & turns the engine over. When the engine speed exceeds the design speed of the bendix (because the engine is running) it disengages. (and I can never remember what RPM that is) All the new style bendix does is allow a higher engine speed before it disengages.

What is happening in your engine is that 1 or 2 plugs fire, the engine momentarily exceeds the bendix disengage RPM.....and it disengages before you have all 4 firing.

If you want to tune it up, just ask; plenty of folks can walk you through that (but see tip # 39 first).

And, if you want to pull the starter & replace the bendix, just ask about that as well.

" how wide of a gap on my tester should the spark be able to jump?"

.25

1/4 inch.
75 Tips
 
(quoted from post at 01:04:44 09/19/14) Thanks Bruce. I'll check all my grounds and make sure the battery is charged and measure volts. The spark coil is wired directly to battery now. Also the starter is spinning out after the engine " catches" Needs rebuilding?
Finally, how wide of a gap on my tester should the spark be able to jump?

20 IS WHAT YOU ARE SHOOTING FOR... S/E IS THE SMALL ENGINE SETTING dead nuts in the middle of s"I"e... Set it 2"I"0 on the "I" line....

You don't need the starter to check fire manually open and shut the points...


What is the volt reading on the bat before you hit the starter button,,,,You can check starter draw with a volt meter ( I can ) what are the battery volts while cranking... What is the battery reading after you let up on the starter button...

If the starter sounds like its cranking the engine over normally """VOLTS""" are all you need to know... The volt reading will lead you in the direction you need to go.. There's NO need to muddy it up with test you can not preform are info that is useless with out equipment YOU do not have...

Edit one more time... pull all the plug wires does the starter still kick out... Do the volt test first...
 

12.7 at start
10.7 cranking
12.5 after stopping

Took plugs out and starter will continue to spin.

I cleaned and tightened grounds, installed #2 battery cables
Things got a little better

I cleaned carb( had some scale rust and clogged up elbow filter)
Ran for twice to as long, but still stopped.
 
(quoted from post at 17:24:08 09/20/14)
12.7 at start
10.7 cranking
12.5 after stopping

Took plugs out and starter will continue to spin.

I cleaned and tightened grounds, installed #2 battery cables
Things got a little better

I cleaned carb( had some scale rust and clogged up elbow filter)
Ran for twice to as long, but still stopped.

Your battery is good
your starter amp draw is a little excessive (in the 225/250 amp range)

What is things got a little better...
is your spark jumping 20KV on the tester...
 
(quoted from post at 17:19:11 09/20/14)
(quoted from post at 17:24:08 09/20/14)
12.7 at start
10.7 cranking
12.5 after stopping

Took plugs out and starter will continue to spin.

I cleaned and tightened grounds, installed #2 battery cables
Things got a little better

I cleaned carb( had some scale rust and clogged up elbow filter)
Ran for twice to as long, but still stopped.
Your battery is good
your starter amp draw is a little excessive (in the 225/250 amp
range)


What is things got a little better...
is your spark jumping 20KV on the tester...

It is jumping to the right of I on S I E . When I rebuilt the carb it started to run little but shut down.

Here is where I am at

It the spark test will really only work with the wire to coil straight wire to battery, but it will not run like that.
It will kick off, but only if choke is pulled way out, will not run
If it were a side distributor I would say time, because it will hiccup a little. I have checked firing order and correct
Put in new plugs
 
(quoted from post at 20:44:23 09/20/14)
(quoted from post at 17:19:11 09/20/14)
(quoted from post at 17:24:08 09/20/14)
12.7 at start
10.7 cranking
12.5 after stopping

Took plugs out and starter will continue to spin.

I cleaned and tightened grounds, installed #2 battery cables
Things got a little better

I cleaned carb( had some scale rust and clogged up elbow filter)
Ran for twice to as long, but still stopped.
Your battery is good
your starter amp draw is a little excessive (in the 225/250 amp
range)


What is things got a little better...
is your spark jumping 20KV on the tester...

It is jumping to the right of I on S I E . When I rebuilt the carb it started to run little but shut down.

Here is where I am at

It the spark test will really only work with the wire to coil straight wire to battery, but it will not run like that.
It will kick off, but only if choke is pulled way out, will not run
If it were a side distributor I would say time, because it will hiccup a little. I have checked firing order and correct
Put in new plugs

its godda jump on the red line with the resistor no if and's ares are butts then we can forget about spark...

If it will not jump to the read line I turn it in till it does if it does I know I am getting a trigger... I then check the wiring and mechanical issues with the dist. My preferred method of eliminating issues is to use a automotive seal-beam head light it simulates a coil and loads the circuit... Voltmeters lie, test lights lie a seal-beam headlight does not....

You would have been better off with the EI instead of fudgen with points... Covering back to points told you NUTTIN...

mvphoto11204.jpg
 
(quoted from post at 19:28:17 09/20/14)
(quoted from post at 20:44:23 09/20/14)
(quoted from post at 17:19:11 09/20/14)
(quoted from post at 17:24:08 09/20/14)
12.7 at start
10.7 cranking
12.5 after stopping

Took plugs out and starter will continue to spin.

I cleaned and tightened grounds, installed #2 battery cables
Things got a little better

I cleaned carb( had some scale rust and clogged up elbow filter)
Ran for twice to as long, but still stopped.
Your battery is good
your starter amp draw is a little excessive (in the 225/250 amp
range)


What is things got a little better...
is your spark jumping 20KV on the tester...

It is jumping to the right of I on S I E . When I rebuilt the carb it started to run little but shut down.

Here is where I am at

It the spark test will really only work with the wire to coil straight wire to battery, but it will not run like that.
It will kick off, but only if choke is pulled way out, will not run
If it were a side distributor I would say time, because it will hiccup a little. I have checked firing order and correct
Put in new plugs

its godda jump on the red line with the resistor no if and's ares are butts then we can forget about spark...

If it will not jump to the read line I turn it in till it does if it does I know I am getting a trigger... I then check the wiring and mechanical issues with the dist. My preferred method of eliminating issues is to use a automotive seal-beam head light it simulates a coil and loads the circuit... Voltmeters lie, test lights lie a seal-beam headlight does not....

You would have been better off with the EI instead of fudgen with points... Covering back to points told you NUTTIN...

https://forums.yesterdaystractors.c
om/photos/mvphoto11204.jpg


I put the points on, got no spark at all and reinstalled EI. All tests have been done with EI. I can get the spark to the red line, but not with the resistor. The coil measures 2. 5 ohms
 
What is the value in ohms of the resistor you are using?

As Hobo asked, where is it in the circuit?

You have a 12 volt coil (2.5 ohms); why are you using a resistor?
75 Tips
 
(quoted from post at 19:20:12 09/21/14) What is the value in ohms of the resistor you are using?

As Hobo asked, where is it in the circuit?

You have a 12 volt coil (2.5 ohms); why are you using a resistor?
75 Tips

He still needs (are can use with are with out his call) a resistor with a square can coil but it must be wired into the right place... Not in the switch feed to the EI.... The EI likes full battery voltage tho it will work with way less there is no reason to add a resistor to the 12V feed going to the EI its self...
 
" a resistor with a square can coil "

Yep.

But just the OEM ballast resistor.

This thread had gotten so long I forgot he had a square coil.....
75 Tips
 
there was one on it when I got it. I took it out of circuit.
I think I have covered pretty much everything, still will not run. I'm going to check EI unit and run a compression check. Going to go back over wiring and battery to make sure I did not miss anything. It must be something simple.
 
Ok I found it! All the electrical advice resulted in a nice blue spark that would jump a 3/8 gap. Still would catch and not run. Ran a compression check- BINGO!!! 1 3 4 had over 105lbs. Number 2 had no compression at all. Looks like a stuck valve. Can't say I'm happy about that, but at least I found the problem and understand the electrical system. Thanks for all the excellent advice on the electrical system. When I fix the valve, it should fire right up.
 
(quoted from post at 22:02:03 09/15/14) I type on a phone, it randomly pics words out of my text and helps me by changing them to completely different words, like bolo instead of color.

Not running on ether tells me you still have spark issues, ether flashes off very easily, anything jumping the gap should make it pop...

Found it. No compression at all in #2. Saw your 15 minutes of work solution in another post. I'll pull the panel this weekend and see if a little cleaning and MMO Or ATF will work. I'm hoping it will since it was running when he parked it. I'm thinking its gummed up from fuel sitting in tank and engine for over a year.
Thanks for all your help
MM
 
Pulled off manifold and took off panel. Intake Valve stuck.
Put a small crows foot between valve And lifter. Applied a little pressure and valve moved. Had filled cylinder with MMO and it helped loosen valve. Turned engine over and valve opened And closed. Put it all back together fired it up and it runs like a top.
Glad I saw your old post saved a lot of time and money. This took About 1 hour
 
cool.. it's what i was expecting you to say. stuck intake.

and yup. mmo, or atf / diesel or atf/acetone is a decent valve unstickem.

glad it worked out for you.
 

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