Spark Plug Terminal Question

[Graham Man]

OK maybe I am dreaming...  Start off 1929 Graham Car.  When I got the car there were several spark plug terminals in a can, they screwed on the spark plug top and then you had a push in connection just like you do in the distributer cap.  You solder the distributer type connection on both ends of the wire and snap them in.  I can not find these things anywhere?  Maybe I was just dreaming?

 

Thanks for any help

[Graham Man]

This might be a picture...but they must have a name?

[PFitz]

They're called "spark plug wire extensions". Graham wasn't the only automaker to use them around that time.   

 

Great for catching and filling with oil spray on leaky engines and then loosing a spark connection as the oil interferes with conductivity.  Been there a few times.  Also not great at holding the wire's terminal end in the socket. The wire terminal often vibrates out of the extension's socket. Been there, too.

 

Not the most reliable type of spark plug connection for a driver car you want to get back home in.

 

Paul

Edited November 3, 2017 by PFitz (see edit history)

[Graham Man]

I would tend to agree.  The area to hold the wire end is too small to hold well, it is interesting that the distributer end connections are the same and stayed around a long time. The distributer cap and the way the boots attach make for better support, and a lot cooler.   My guess is it was the best thing going.  They just came off of screw caps to hold the wires, they must have loosened up all the time with heat cycles and just fell off?  Just after this 35-36? came the snap on connectors that were 1000% better with the heat cycles.  Most likely as the connections fell off they were replaced by snap on connectors.

 

Now make it original or reliable...

[PFitz]

The distributor caps and coils are cast and have an enlarged area down in where the wire terminal sits.

 

Those brass spark plug wire extensions are machined and being just a straight tube inside where the wire terminal fits into it, there's nothing to hold the terminal end in place except the slight friction of the outward springiness of the wire terminal.  Vibration and oil can easily overcome that.

 

Paul