8N not starting

Hello:
I own a 1951 8N. In the 11 years i have owned it, she has never had trouble starting...until today. The engine cranks very nicely, but i get the smell of fuel quickly, and she never catches. The first thing i did after she wouldn't start was change out the sparkies (H-12's) for a fresh set of 437's, but she still wouldn't catch. There were a few drops of gasoline coming off the bottom of the carb. Can anyone suggest a next step in diagnosing this issue?

Thank you
 
jackman.......keep yer itchy-twitchy fingers off'n them handy-dandy carb tweek-ums.

You made a good guess that you FLOODED yer sparkies. Changing to AutoLite 437's gapped 0.025" was good start...BUT...it sounds like you may have RE-FLOODED yer sparkies. The UP-draught M/S carbie FLOODS very eazy.

Turn yer under the tank glass fuel screw OFF. Pull yer airfilter rubber hoze off'n the carb intake. Let yer FLOODED carbie DRY out. RE-MOVE yer brand new FLOODED sparkies and lett'em DRY too. You might wanna dry yer NEW flooded sparkies with a propane plumbers torch. Otherwize yer gonna be settin'round fer a while waitin' fer DRY sparkies.

Remember, even in COLD weather, ittza 2-rumpa-rumpas before you giff yer spring loaded choke knobbie a QUICK pull. Yer DRY sparkies should sparkle yer engine. Now "feather" yer choke knobbie 'till it runs smooth at idle and off'n you go. Simple, eh?

Yer M/S carbie holds about 2-mins of gas fer startin', so you don't haffta be inna HURRY to re-turn yer GLASS filter wheel to 2-turns. And while yer gastank is supposed to bee vented thru the DOME at the front of the tank, mudd-daubbers are known to CLOG the VENT. So it never hurts to Open yer gascap and un-vent the VACUUM ...and... lookie-see iff'n you really due have gas in yer tank.

BTW........same advise fer either the original 6-volt positive (+) ...or... 12-volt negative (-) electrical system. .......sparkie-meister Dell
 
Have you checked for spark at the spark plugs? Very
likely weak spark if points have not been changed in
11 yrs..
 
(quoted from post at 23:55:30 11/16/14) Have you checked for spark at the spark plugs? Very
likely weak spark if points have not been changed in
11 yrs..

I will check the spark. The last time it had a new set of points was 11 yrs ago!
 
Good luck getting GOOD new points-I'd stick with
Napa and wherever you buy them, don't get any with
the plastic rubbing block (they wear down quick and
then your gap is wrong) and remember to get points
cam lube..tuy dot does it but u will probably have
to buy a tube that will last several lifetimes..Keep
us posted on your progress-- Thanks
 
I just bought points from NAPA, Echlin brand, and they have the phenolic rubbing block. There was also a tiny capsule of cam lube in the box.
 
Spark needs to be a good blue/white in color and jump a 1/4 inch gap or more. Now days it is best not to replace the condenser due to so many being bad right out of the box. Point gap is 0.025 by the way
 
(quoted from post at 19:06:15 11/16/14)
(quoted from post at 23:55:30 11/16/14) Have you checked for spark at the spark plugs? Very
likely weak spark if points have not been changed in
11 yrs..

I will check the spark. The last time it had a new set of points was 11 yrs ago!
For the side mount, Standard Ignition Blue Streak# FD-8081X
or NAPA Echlin# CS753 are a good bet. Both usually have a
small capsule of points lube with them, but not always.
Be prepared for sticker shock. Here they're still less than $20.
 
Amazing---I didn't know any of them still had the
cam lube in them. Last two sets I bought were from
one of the other "automotive parts stores" and
both sets were defective-one grounded out at the
pivot point and the other had wrong slots such
that adjustment could not be accomplished--and No
I was not going to file out the slots-they are
suppose to work out of the box----anyway, no
grease with them-I guess they knew they would
never work so no need for grease....Got points at
Napa(this was for 65 Mustang)You could see the
difference in quality and they worked fine-month
or so later changed it to electronic ignition
module and hadn't been sorry yet......
 
"I didn't know any of them still had the cam lube in them"

When I buy them here, unless you buy the "premium" versions
they don't. For example, the SI part number I listed. If you get
the same number without the "X" on the end. Not vented either.
But some parts stores will sell the cheaper version and rob the
cam lube out of a premium set for their "regular" customers.
 
" There were a few drops of gasoline coming off the bottom of the carb. "

First, replace the plugs. If you flooded it, they're fouled & it will be it next to impossible to start. You don't need to toss them; heat the tips for a few seconds w/ a propane torch to burn off the invisible spark-robbing deposits from today's additive filled gasoline........or wash them in lacquer thinner.

The usual cause of gas dripping out of the carb throat is operator error.

While each N has its own starting sequence, none of them will start well by just yanking out the choke rod & holding it out for 5 or 10 seconds while the engine cranks. This is a gravity fuel system on a low compression engine; it is easily flooded by too much choke.

Try this:

Key on, gas on 2 full turns, clutch in, 3/4 throttle, press the starter button. Let it crank for at least 3 - 4 seconds before you pull the choke rod. Then, don't hold it out for more than 2 or 3 seconds.

If you find out it will not start w/o excessive choking, you have problems.

Coil problems are difficult to diagnose. For starters, round coils are pretty robust & square coils aren’t (because of the difference in insulation used), but neither one will hold up to a poorly done 12v conversion that allows too much current to the coil or leaving the key on (see tip # 38). Too much current creates heat which melts the insulation. Insufficient resistance in a 12v conversion will do the same thing. Rarely do coils just “go bad.”

As others have said, there are a few ways to see if a coil is bad, but it’s not possible to determine if a coil is good w/o some expensive testing equipment. If you detect a dead short or high resistance in the coil w/ an ohm meter, it’s bad. If it’s cracked, it’s bad. If a sidemount coil w/ battery voltage to the primary will not jump a ¼” gap from the secondary wire to the block, it’s bad. But, here is the hard part: even if you do not detect a short, even if it will produce a spark, even if it’s not cracked, that doesn’t mean the coil will work when it’s hot & under a load. So, it’s a process of elimination. If the tractor starts & runs fine for 30 minutes or an hour then cuts off & refuses to re-start, and you checked for spark at the plugs & it had no spark at all, AND you have the correct voltage at the coil that’s a good sign that you have a bad coil. Let it cool off, restart it & if you have a good spark, odds are it’s a bad coil. But, even then, you might end up w/ a spare coil on the shelf!

Bottom line.......coils do go bad, but I'll venture a guess that 75% of new N coils sold today are sold to folks who do not understand how to diagnose a poor spark problem or how a coil works. So, for those who don’t know any better, in a no spark situation the first suspect is usually the coil……and, more often than not, it isn’t the problem.

Or as one regular around here humorously suggested: "Well, it is like this...I don't know or really understand what that black thing does & I am suspicious of the unknown, so I think the problem is the black thing."

Do you have battery voltage across the points when they are open? Verify the gap on the points at .025. Then, dress the points by running a piece of card stock or brown paper bag through them. New points sometimes have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. (I always spray my feeler guage blade off w/ contact cleaner.) Make sure you have voltage across the points, as in past the insulator on the side of the distributor. That is a very common failure point on sidemounts, along w/ the attached copper strip. It's hard to find a short there because it is usually an intermittent . So 'wiggle' the insulator & the copper strip a bit when you are doing your checking. If you find the short there, the Master Parts catalog lists everything you need on page 154. You can make the strip and you could also make the insulators as well. But, somethings are just easier & in the long run cheaper to buy. Get the strip, 12209, screw 350032-S, 12233 bushing & 12234 insulator & just replace it all. If you just replaced the rotor & lost spark, put the old one back in. Insure that the rotor fits firmly on the shaft & that the little clip is there. Make sure the distributor cap is not cracked & doesn't have carbon tracks. Check continuity on the secondary coil wire. Make sure it is firmly seated in both the cap & the coil. In fact, replace it temporarily w/ a plug wire. Next, remove the secondary coil wire from the center of the distributor cap, turn the key on & crank the engine while holding the end of the wire 1/4" from a rust & paint free spot on the engine. You should see & hear a nice blue/white spark. If not, you have a bad coil or condenser. Just put the old condenser back in to eliminate that as a possibility.

Post back w/ results; I'll be interested in what the problem was.
75 Tips
 
Just wanted to follow up with everyone (and i posted this in another thread as well)...after going thru the recommended diagnostics, i replaced the points to no avail. After reaching my breaking point, i went to disconnect the battery to bring it inside to trickle charge. It was then i noticed a wire hanging loose behind the dash. I re-attached the wire (top blue-ended wire in photo below) and was able to fire the tractor up and she ran beautifully...


mvphoto13280.jpg
 

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