I purchased a new ignition switch for my 55 a while back. Lately, while driving it I notice the autometer speedometer and tach sweep like they have lost power, but the engine never shuts down. Today while on a short drive the engine actually quit.

Has anyone experienced a bad or degraded ignition switch. It could also be something in the existing makeshift wiring, but I hate to install the new wiring harness until after the paint and body is complete. There is a myriad of errors in this wiring and while I have corrected many I am sure it could be a ground or faulty connection if not the switch.

 

You could try temporarily adding a jumper wire (like the alligator clip kind) across the switch and take a spin to see if the needles still are intermittent. That technique can also be used to prove out a ground. Just don't forget to remove the jumper.

 

I assume from your post that it is the new switch that is in it now when it is doing this? Right? Was it doing this Before ya replaced the switch? Why did you replace it?
If doing the same thing after replacing the switch than I would suspect something else. Not to rule out that a new switch can't be bad out of the box. It is more common today than ever with the Made In China crap we have to buy.

Try what Jeremy/Dylan suggested and get back to us.
If it quits with the jumper on the switch ya can always jump from the Batt + to coil + to get her home. This is the "Hot Wire" trick we used back in the day to go joy riding in cars we could never afford on weekends. And being just school kids we would just get a slap on the wrist if caught. And of course a woopin from the ol' man.

 

Not sure what I would be jumping across. If you can explain.

 

Not likely the switch...more likely an electrical connection. As with most old wiring, any disruption of the wiring can cause intermittents either at the junction of the wire and the connector or at the junction of the connector with the gauge/switch/etc. If you are not skilled with a voltohmeter, now is the time to learn how to use one. They to be so expensive that only businesses had them...today Harbor Freight gives them away free with a coupon.

 

Any wire from a known constant voltage source such as the battery or starting relay is a place to hook one end of your wire. The other end goes to the side of the coil that does not run to the distributor. This wire will by pass a problematic ignition switch or wiring. Do not let the wire hooked up for long unless the engine is running, it will burn the points if they happen to be closed. As suggested, now is the time to get and learn to use a meter.