8N wont start

Gentlemen I am back. Had issues with front mount distributor about 3 months ago and after recommendations from forum, I put in new bushings, breaker plate, blue streak
points, new condenser and it started and ran fine.

So now it won't start again.
What I have found/worked on.
Battery 6.3 volts measured by multi-meter on battery posts.
Prior discussion found no issues with resistor or current to the coil.
I have taken off carb, removed the jets, cleaned with carb cleaner, used air hose to blow dry, sprayed with carb cleaner second time, air hosed to dry, (all parts
before reassembly)
checked gas flow, fills jar as noted in the 75 tips
checked spark, I have spark using spark tester light.
Took out plug tried the 1/4 inch spark test (as noted in the 75 tips) does not spark.
Used starting fluid at carb intake, no impact.
Engine does turn over well and will disengage starter like something wants to fire off, but that is all it does.
So what should I check next?
Thanks in advance.
 
" Took out plug tried the 1/4 inch spark test (as noted in the 75 tips) does not spark."

First, throw the spark test light away. As you just proved by testing spark correctly, you have a weak spark.


The first thing you need to check is for battery voltage at the coil. Yes, you need a meter for that, not a light. With the key on, you should see battery voltage battery with the points open and about half that with the points closed. If you do not see either, the problem is between the battery and the coil, e.g., the resistor, ignition switch or a bad connection.

Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil , the most common reasons for no spark or a weak spark on the front distributor are below. Check each one carefully. Even if you find a problem, check all 10:

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) Check for continuity between the top of the coil and the pig tail; a 6 volt coil will be around 1 ohm & a 12 volt coil should be 2 to 3 ohms.

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

4. The distributor is not grounded to the block because of paint or grease acting as an insulator. Or the points plate is covered in oil.

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.) Check for continuity between the top of the coil and the tab; you should see about 6k ohms.

6. A grounding issue inside the distributor: 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) or the condenser wire is grounding to the plate or side of the distributor.

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. If the tractor has been sitting unused for a few months, it’s highly likely that the points are glazed. Dress them with brown paper or card stock. Do NOT use a file or sandpaper. That removes the thin metallic coating on the surface and reduces point life considerably. With the points closed, you should have continuity between them; high resistance means they are glazed.

10. Burned rotor, cracked/carbon tracked cap. Brass “dust” in the cap is a sure sign of bushing wear.

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.


* Unscrew the plate hold down screw & remove the C clip to get the plate out. Remove the shaft & weights. The weights should freely move. The tracks should not be wallowed out.






** Distributor cam lube NAPA:

https://www.napaonline.com/en/p/ECHML1
75 Tips
 
Bruce, thanks for info, will take it one step at a time. Will check voltage between wire into coil to make sure the same as from battery.
Then proceed to the nest step.
 
Bruce, in your comments you state "points open..points closed". So every engine I have worked on when I had to check something "open/closed", I took off cap and looked. Front mount does not allow visual. So, yes, this is a learning experience for just a back yard mechanic. Please explain if there is a way to determine "open or closed" without removing distributor. Only thing I could find online for any distributor was to keep points open, rotate flywheel until points opened. Doesnt work for a front mount. Thanks
 
attach your volt meter to the stud on the coil, the n put the other lead to ground.

turn the motor by hand.

points open, battery voltage.

points closed, about half that.

No voltage change? you found the problem.
75 Tips
 
Bruce I checked the battery voltage and get the correct readings. Open battery voltage, closed about 1/2. Then I removed the distributor and checked everything and since the points, condenser and breaker plate are new there did not appear to be anything shorting out or broken. And the tractor started fast after I installed those new
parts previously. It ran for 1/2hr to an hour before letting it set for a couple weeks. No moisture inside distributor, everything dry, no oil, etc.

So I checked the coil ohms, one lead to stud on top, other to pig tail. It reads a fast 1 ohm then drops to .9 and then .8. Is that normal since you said the readings would be around 1.

finally, when I remove the plug and use an old plug set at a 1/4 inch gap, does any part of the plug need to be grounded to the block. Want to make sure I check that properly. I am going to verify previous test before going any further.

Thans again for your time and info.
 
R.G. That is what I thought, but wanted to verify. This has been a learning experience on how many things
can be wrong before finding the problem. I thought I knew how to work on engines until I ran into this
thing. Rebuilt 51 ford flathead, 55 Old V-8, fixed no start problems on other old cars, but this one has
provided a problem like a needle in a hay stack.
 

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