No spark

[67coupe200]

67 i6 200. original points ignition, damper and timing chain still in use.
that being said at certain rpms the car would jerk on the clutch and drive shaft back and forth until i either let off the gas or accelerated, this would occur at a constant speed only or cruising speed rather. Thinking this might be some kind of timing issue i went to inspect and gap the points as well as check ignition timing. When i started to check the ignition timing with my timing light i noticed that the flash on the light was erratic and not proper so i proceeded to advance the distributor in an attempt to fix the problem, when i did so the light stopped flashing all together so i checked the other cylinders and the first three were not firing but the last three were firing in a healthy constant speed?!? So i double checked the timing, point dwell, and the vacuum advance. all seemed well except the advance was not functioning, but the first three wires were not firing at any rpm.
After tweaking the distributor i got the first cylinder firing erratically only now the 2nd and 6th cylinders weren't firing. After that i left it alone and now here i am without a mustang .
I'm leaning towards the timing chain but i cant be sure, What do you guys think?

 

[bubba22349]

If it is firing on three or four cyc. it can't be the timing chain try a new distrib cap or a new set of wires

 

[fordconvert]

Did you try a dwell meter? 1st to confirm that you have them set properly and 2nd to see if the reading is steady through the RPM range. IF the reading jumps around it could be that the bearings in the distributor are worn and letting the shaft bounce around thus letting the dwell float around.

Other thought is get your ohm meter (or test light) and connect it to battery + and then to the wire from the points. Rotate the engine so the points are closed then flex the wire around. Even better get a vacuum pump and operate the vacuum advance. Its possible that your wire is cracked and when the vacuum advance changes its breaking the connection which makes the engine stumble which changes the vacuum signal so it moves back to where it makes contact again. Same thing would happen if you changed the timing, vacuum changes so signal changes so wire flexes. Could also be the ground wire that goes between the plate the points mount on and the body of the dizzy.

Last thing could be the points are just sticking. Had that happen on my 66. Only caught it having the tach hooked up.

 

[67coupe200]

although i did change the plugs, and i believe the points to be in working order, Ive found a replacement dizzy for 40 bucks so ill install that today and let you guys know what happens.

 

[rbohm]

8) first thing to do is check the condition of the points. i have run across sets that seemed to be in good condition, even had good dwell readings most of the time, but the engine had a severe miss. when i would check the points, i usually found that there was a ridge or a ledge on one side that would sometimes prevent the circuit from opening up and creating a spark. next check the condenser to make sure it isnt a direct ground. third make sure you have power through the coil. after that check the plug wires for proper resistance.

 

[67coupe200]

yeah i got the distributor replaced, but now i cant get the car to run at all. I found TDC on the first piston and got the rotor set on the first cylinder and it all went together but just wouldn't start, so im guessing that its not installed properly or something else is very wrong

 

[ludwig]

Dizz 180* out when you replaced it?

Make sure you have TDC on the compression stroke and then get the rotor to head for the #1 plug.

 

[67coupe200]

its installed correctly but im having other issues. *see post "arc on balancer"

 

[ludwig]

I read that one. Look at your grounding once more. There should be the heavy negative battery cable running DIRECTLY to a bolt on the side of the engine block. Then there should be a strap or a medium gauge wire bolted to the back of the block or to the starter motor mounting and bolted to the face of the firewall just above or behind it. Check these carefully for rust underneath them. Disconnect them and wire brush them down to bare metal in both places on both sides of the connection. Because if there is enough rust, they stop conducting. The rust becomes an insulator and the power will find a path of lesser resistance, like out the front to the damper.