1951 8N - No Spark

This is an update to the thread "1949 8N - No Spark". Turns out, this tractor is a 1951 (engine was replaced after a flip). That makes the distributor a side mount, 6 volt.

Thus far, we have replaced the battery, coil, cap, rotor, plugs and wires, and points (tried gaps of .015 and .025), but have no spark. We have bypassed the ignition switch and ran a negative wire directly to the coil. We have voltage present at the condensor in the distributor. I have a spark at the points.

I wrote down the firing order but have lost the slip of paper, could someone post that for me as well?

Any other ideas or suggestions are greatly appreciated. Thanks!

(quoted from post at 17:56:22 09/20/10) This is an update to the thread "1949 8N - No Spark". Turns out, this tractor is a 1951 (engine was replaced after a flip). That makes the distributor a side mount, 6 volt.

Thus far, we have replaced the battery, coil, cap, rotor, plugs and wires, and points (tried gaps of .015 and .025), but have no spark. We have bypassed the ignition switch and ran wires directly to the coil (positive and negative sides). We have voltage present at the condensor in the distributor.

To properly set the points, does the distributor need to be removed from the engine? We made sure the part of the points that rests against the cam and weight assembly is against a flat side and not a corner during the attempt to adjust the points.

I wrote down the firing order but have lost the slip of paper, could someone post that for me as well?

Any other ideas or suggestions are greatly appreciated. Thanks!

Click to expand...

You are hurting my knee, pulling on my leg!

" We made sure the part of the points that rests against the cam and weight assembly is against a flat side and not a corner during the attempt to adjust the points. "

Hope yer joking but if not the points need to be on the high point or lobe of the cam when adjusting them. That way they close when they get to the flat spot.


Rick

Do not remove the distributor! If you do, you will spend another hour on this board having static timing explained to you!

Firing order is 1-2-4-3, CCW.

Point gap is .025, not .015.

And, if you are setting the gap on the flat of the cam, you are setting the gap incorrectly. Set the gap w/ the rubbing block on the high part of the cam. Make sure the blade is at a perfect right angle to the points & you want to feel just the slightest bit of drag when you pull the blade through the points. Make sure the blade is clean & that you dress the new points by running some card stock or a piece of brown paper bag through them. Make sure the points align correctly.

Even as tight as I am, I always change the condenser when I change the points…….and then I toss the condenser in the “used” parts box. A bad condenser is rare; you can tell if the points are pitted/burned w/ metal transfer.

Good hold-down screws are important. (tip # 37) If the heads are wallowed out, what do you think the threads look like? You can use machine screws as temporary replacements, but you should use the OEM Fillister head screws. The larger head is there for a reason. If you do use standard machine screws, make sure they aren’t too long & interfere w/ the advance weights. Always use star washers under the screws.

Do you have battery voltage across the points when they are open? 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.
50 Tips

Hey there I am so proud of you both in the way you handled that post. It was just laying there open to a barb or two and as good troopers you played it as a comedy and that is truly heart warming. Sure wish ole JMOR was here closeby and could be hired on , I would get my machine into top running condition. I would promise total silence and hostile movements at all times and just watch my machine come to life. There is no doubt that he knows his Chit but I am hard to get along with at times. But "Pulling my leg and hurting my knee" wasn t something I expected to come out and I actually felt let out of the dog house a slight distance. Good on ya guys. Devious

Just as an update. I went back to the tractor after seeing Bruce's post. Before doing anything, I checked for a spark at the points. It did spark, but while looking closely, the points never touched. I adjusted the points against the corner of the cam to .025.

After doing this, I lost the spark on the points. I checked for voltage on either side of the points. What I found was .3 volts from the side of the points connected to the coil to the positive terminal of the battery. The other side of the points had nothing to positive on it. When I went to the negative side of the battery, the side bonded to the coil had near 5.4 and the other side had around 5.8. Looks like something is grounding out.

After seeing this I began to inspect the screw, seals, and copper strip. A few wiggles on the strip caused it to snap at the base.

I did not have a spark before I replaced the rotor and the dist cap is new and in good shape. The threads and heads on the screws are clean and in good shape as well.

Looks like my next step is to replace the screw, seals, and strip. Sadly, my local TSC did not have the parts on hand. Thanks for the tips and for being understanding, Bruce, I have never owned or worked on a tractor before.

" Sadly, my local TSC did not have the parts on hand."

That's not a bad thing; many folks have been disappointed w/ N ignition parts from TSC. You can get the parts you need from this site or nnalert's. NAPA carries all you need except the copper strip & insulator.

" I checked for a spark at the points. It did spark," Well, you did exactly what I said.....but that's not what I meant! With the points open, place one probe of your meter on on side & the other probe on the other side. You should see battery voltage: 6.35v. You are seeing less. That means the tractor battery is low, the battery in your meter is low, or you have significant resistance in the circuit. Check the voltage at the battery.

"I have never owned or worked on a tractor before. "

Well then, you are doing pretty good then. It's not all that difficult to replace the insulator & copper strip. Then, you will have it running.
50 Tips

I ordered the parts you listed and have installed them. I went to try and crank the engine and check for a spark. The engine cranked once then quit. Engaging the starter button does nothing now, as though it was disconnected. After looking in the manual, I found that all the button does is ground the starter, so I ran a jumper from the positive terminal to the spade connecter outside the starter button. The engine made a noise, but did not crank. This led me to believe that the button has failed. I went to remove the old button, it turned easily for 1/4 turn then I hit intense resistance. Rather than risking damaging something I shouldn't, I figured I'd relay this information and see if there is something about that button I am missing. (Something like it having a nut on the other side of the plate it attaches to.) Thanks!