Re: 356ci Engine Stalls

Posted by HH56 On 2021/12/23 10:26:08

Intermittent issues are always such fun to try and track down and there could be several causes. If the mechanic is definitely leaning toward a spark issue then here are a few ignition related possibilities. Of course fuel issues cannot be ruled out either but that is another discussion.

The cloth covered flexible wire inside the distributor having a chunk of the old fabric insulation fall off and possibly short when the advance plate moves is a known issue. This issue is frequently found out the hard way when new points and condensers are installed and the wire is disturbed during that work.

Condensers -- even brand new out of the box -- are also known to cause intermittent issues. If too long a screw is used in holding down the points or condenser that can cause some issues.

If your car still has the original firewall mounted coil -- or even a different but still older coil -- heat is a very well known problem with the older coils. It could be opening up when warm and working again after it cools down a bit. You could get a universal 6v coil from the parts store and temporarily use that to see if the problem persists. If you have the original firewall coil you would need to figure out a mount method and how to get the power wire thru the firewall to the new coil.

I can not say if the aftermarket ignition switch might be an issue. A 12v switch could be under capacity for the amps needed in a 6v system and could have a similar heat issue. It could be losing contact when it warms up and something expands inside the switch. One way you could eliminate the ign switch as a possible cause is to in effect temporarily hot wire the car. Run a wire directly from the battery connection on the starter solenoid to the ignition switch terminal of the coil. On the stock firewall mounted coil this would be the terminal on the base of the coil accessed from inside the car. Downside is when hotwired the only way to kill the engine would be by disconnecting the battery or the wire. To avoid having to get out and disconnect the battery when ign switch is bypassed you could put an ordinary toggle switch in the wire where you could reach it and then turn off the engine .

If the car has overdrive and still has the original wire loom with the fabric and rubber insulated wires there could be an issue with shorting wires in the old loom. An intermittent short somewhere in the ign cut off circuit could kill the spark if vibration caused the wire to touch metal or another wire. To rule out that possibility temporarily disconnect the second wire on the coil coming from either the R9 OD relay terminal 2 or the R11 kickdown switch. That wire would be on the same coil terminal that is connecting to the distributor. You can still drive the car with the wire disconnected but it will not have kickdown capability so getting out of OD would be an issue when the wire is disconnected. As far as old wiring goes, even the regular wire present on all cars going from the coil to the distributor terminal could be suspect if there are signs of bare wire.