Weird timing/ignition issue

[improbcat]

Argh, just went out to work on the Comet, cranked the engine once and the start died. Kaput, nothing. Even tried hitting it with a hammer to no avail. So now I need to add a starter to the list of things I need to get my engine running right.

Did swap the new distributor for the old one as the misfire is the same with both so no sense in spending the money on one that does the same thing as the old one.

Have new cap, rotor, coil & wires going on as all of those are somewhere near 5 years old.

Will update once I have a new starter in and can try again.

 

[improbcat]

An update.

Got the Starter in so the engine would start again. Also installed new cap, rotor, coil & plug wires.

After all that, the miss is as bad or worse than before.

At idle you can notice an occasional subtle miss, as you increase the RPMs the miss becomes more frequent and more obvious to the point where it seems like the engine isn't firing on all cylinders. However if I pull each plug wire in turn they all cause the engine to stumble meaning the miss isn't just one cylinder not firing. not hooking up the vac advance on either distributor makes the miss not *quite* as bad, but still very much there.

At this point I have replaced plugs, wires, cap, rotor, & coil. And have tried both the old distributor with a Pertronix unit, and a new rebuilt dist with points. None of this caused any change in how it runs. When I changed the plugs out they all looked similar with no obviously different cylinder. I am at a complete loss.

 

[66200i6]

Now you can take those measurments so you have an idea of what to do next.

Good luck, Ric.

 

[improbcat]

Now you can take those measurments so you have an idea of what to do next.

Good luck, Ric.

I don't see how taking readings of the vacuum advance is goign to help me find a misfire if it happens regardless of the advance being hooked up or now. Could you clarify this for me?

 

[66200i6]

The readings only confirm what is actually happening with your advance and will provide the rate of change with RPM and vacuum.

If your advance at idle is 12 BTDC and it jumps to over 50 just off idle (ported vacuum) you know that you need to dial back the pot on the distributor a bit.

Without knowing what is actually happening, it is difficult to impossible to fix.

Good luck, Ric.