coil

[vincent figaro]

any way to test 6 volt coil 2n front mount without test light ?

thanks

 

[Bruce (VA)]

" any way to test 6 volt coil 2n front mount without test light ?"

Sure.

You could use a multi-meter, but that still won't tell you much. That's because 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.?

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 ?? 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."

So, what problem are you having that leads you to suspect a coil failure?
75 Tips

 

[vincent figaro]

don't know where to start cut off the other day cutting a ditch for water pipe would not start back getting good gas flow put new gas valve on new points rotor button condenser set points at 0.15 1945 2n front mount 6 volt got fire at wire to top of coil not real sure about little copper wire in points have under 2 top screws in dist. feel sure it's right though no fire at spark plugs thanks for any help not the best on old tractors ???

 

[Bruce (VA)]

There are 2 chances your coil is bad: slim & none.

Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil (battery voltage with the points open and about half that with the points closed.....what is it?), the most common electrical failure (no spark, weak spark) points on the front mount are:

1. The insulator under the brass concave head screw & where the copper strip attaches. (it?s fiber & will wear out; poke & prod w/ your meter leads to make sure it still works) If you need to replace the insulator, use a .250 x 3/8 nylon square nylon anchor nut available at most big box home stores


2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark

3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks).

4. The condenser wire grounding to the plate or side of the distributor.

5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.)

6. Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o?clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o?clock)

7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

9. Dirty/corroded/burned/incorrectly gapped or misaligned points. I use only Wells, Blue Streak or Echlin brand points (* *see below). If you are using quality points and cannot get the gap to open to .015, chances are you need to replace the bushings. If the shaft has any sideways movement AT ALL, the bushings must be replaced.

10. Burned rotor, cracked/carbon tracked cap.

After find the problem & re-check the point gap, do a continuity check before you put the distributor back on the tractor. Before you start, make sure your meter/light works.

With the distributor still off the tractor, follow these steps:

1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil misaligned trying to put it back together, one piece at a time. The result is something gets broken or you get a ?no spark? problem.

It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. Whatever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts). Place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Hand tighten the two bolts until the distributor body is flush with the timing gear cover.

* Unscrew the plate hold down screw & remove the C clip to get the plate out. Remove the shaft & weights. The weights should freely move.

* *NAPA part numbers:

? Points: FD-6769X
? Condenser: FD-71
? Rotor: FD-104
? Cap: FD-126
75 Tips

 

[vincent figaro]

thanks for help will try again will let you know

vince

 

[vincent figaro]

forgot to say dist.cap did not look the greatest 4 contact on inside seem to be wore pretty bad may pick one up hope that's it !!!

 

[Dell (WA)]

Vince.........would it surprize you to learn your ROTOR should NOT make physical contact with yer distributor contacts??? Them little HI-VOLTAGE electrons will willingly JUMP the little distance. When you inspect the INSIDE of yer dizzy cap, look fer STREAKS and CRACKS ...NOT... burned or corroded contacts. .......HTH, Dell, yer self-appointed sparkie-meister