Ignition Wiring - No Spark 1974 1F

[cstav86]

1974 40 Series 1F
Need some help with my ignition wiring, not getting a spark at the plug. Grounding it to the block when turning the motor.
New coil - no external resistor required - pretty sure this is wired up right, please confirm.
New dizzy rotor, cap and wires.
Gear reduction starter. There is an extra wire here shown in the last picture. From my homework it is not required - can someone confirm?

An help is greatly appreciated!

 

[Coolerman]

That is correctly wired, so you need to check for the following:
Do you have +12V (battery voltage) on the Black/Yellow wire connected to the coil + when the key is on? If not could be a bad fuse, key switch, or bad connection somewhere in that circuit. Could be something as simple as dirty fuse block contacts.

If you do have +12V on the Black/Yellow wire, then try this: Get a known good spark plug, pull the coil wire off the dizzy and attach it directly to the spark plug. Attach a clip lead to the coil -. Now ground the spark plug and touch the other end of the clip lead to the battery - post and remove it as fast as you can (simulating the points closing and opening). The spark plug should spark each time you do this. If it does, you have a points issue, a dizzy that is not grounded, or a problem in the black wire going from the coil - to the dizzy.

If it does not spark you have a coil issue.

 

[cstav86]

@Coolerman Thanks!

 

[cstav86]

@Coolerman so ive got a points issue/not grounded dizzy or black wire problem because it sparks when I do the clip lead test. I ran a wire directly from the (-) coil side to the dizzy and still no spark. Any suggestions on what to check next? Can I ground the dizzy directly to the (-) side of the battery?

 

[65swb45]

Your list of replacement parts does not include the points. That’s where I’d check next.

 

[edwjmcgrath]

Your list of replacement parts does not include the points. That’s where I’d check next.

What he said. If you don’t have quick access to a new set of points, a minimum, make sure that the points open and close when the engine cranks. Pull off the cap and rotor and visually look at where the rubbing block rubs on the 6 sided cam in the center. Have someone tick the starter while you are watching until the rubbing block is on one of the high points of the cam. Then check if the points are open. Should be open about the thickness of a matchbook cover (old school dwell meter ). Repeat until the rubbing block is at a low point. Now the points should be touching. WIth the ignition on, use something non conductive to manually open and close the points. You should see a little spark at the points.

 

[cstav86]

@Coolerman Resurrecting this thread as I have somehow lost spark again to my plugs and cannot figure it out. THANKS IN ADVANCE FOR THE HELP! Here's what I have done so far... pictures should follow numbering:
1. Verified the coil is good by doing the clip lead test. It only works when the black wire is disconnected from the dizzy. ANY ISSUES THERE?
2. Verified there is power to the (+) side of the coil, see picture.
3. Dizzy appears to have a good ground, .3 ohms resistance, see picture.
4. I installed new points and I think they are right, see attached pics.
5. With points open, the internals of the dizzy has almost 24 ohms resistance... ANY ISSUES THERE? With the points closed, resistance is negligible, which means its grounding the coil and should release the spark right?
6. I pulled the dizzy to install the points and re-installed to where when the rotor seats it rotates to the #4 cyl. Motor was at TDC with cyl #1 at full compression.
7. @edwjmcgrath With the ignition on, I cannot get the points to spark like you mentioned. Any thoughts there?
8. Just for trial and error I ran a clip lead from the battery (-) to the dizzy and tried to fire. Nothing.

Points Closed:

Points Closed Resistance:

Points open:

 

[cstav86]

Here are the rest of the photos. @cwwfj60 if your interested to follow along. The condenser is new also.

 

[edwjmcgrath]

Several questions: Your battery voltage measured at the coil is 11.25? Very low. What is the voltage at the battery terminals? You should get pretty much the same voltage at the coil with the points open. And with the points open you should have near zero resistance from the dissy body to the battery negative. 23 ohms is a lot. Check your ground cables. Meanwhile, you can bypass them by running a good size jumper cable from the battery negative to the dissy body. What is the “jumper” I see in the coil positive wire? Does your coil have an internal resistor or not? And has anything in the wiring or components changed since this was working?

 

[Danforth]

I once got an OEM Toyota breaker set that used an insulator that could allow the spring and breaker arm to short to ground if the breaker arm and spring was misaligned at installation. The problem was hard to spot. Once in place correctly, it stayed proper forever after. You can test that by opening the breaker arm with a non-conductive stick and measure resistance to the other, stationary breaker point.