Ignition switch

Ron,

Are we still talking about the P-A truck? It would probably help if you were specific about what the vehicle is. I can send you photos of the switches in my Series 36 Dual ign 6, but I doubt they are the same. It is a weird three pull switches (L, R, Both) mounted on a single brass strip.

Dave

With a single distributor, dual coil, dual spark plug setup, it could be a single on/off ignition switch, or it could be like a Series 33/36 with a ‘both’, Left, Right switch.. like David said: pretty complicated..

What is the ‘hole’ in the instrument panel look like [photos ?? ] is it a single opening, a bar of switches on the bottom of the dashboard or ???

Greg Long

The back side.

Ron,

I did a search of the Service Bulletins with no result. Pierce-Arrow Truck info seems to be a challenge to find. As Greg mentioned, post some pictures perhaps someone here might be able to help you.

Hello Ron. Your one-distributor/two-coil ignition system is similar to the 8 cylinder cars’ systems, at least some of the Pierce 8 cylinder cars had two coils, with each coil firing only 4 spark plugs. The 8’s only have one spark plug per cylinder. Properly adjusting the points is critical to getting proper timing.

With your system, each coil fires 6 spark plugs. But each cylinder has two spark plugs. The use of two spark plugs is to more completely ignite the fuel mixture, and to provide reliability.

The T-Head engines that have two spark plugs per cylinder often state in the owners manual to time one spark plug to fire a degree or two later than the other. I have found and most other owners of two plug per cylinder engines have told me that it is ok to have both plugs fire at the same time.. I can’t feel or measure any difference in engine performance using the same ignition time for both spark plugs. I suspect that the poor fuel in the time period when these engines were developed had a lot to do with this staggered-firing of the ignition’s spark.

The actual spark is generated when each set of points opens. So you set the spark timing by observing the points, or using a 6-volt test light. With a 6v light hooked to the wire leaving the distributor going to the coil, and the other end of the test light grounded, the light will light-up when the points open. If you do not have a 6v test light, simply observing when the points open [they generate a small spark], this is when the coil generates the much higher voltage current to create the spark at the spark plug.

Exact timing on these low compression, slow turning engines is not as critical as it is with modern high compression engines. Usually only extremely retarded [late] spark will cause a loss of power and extra heat in the exhaust and cooling system.

I hope this helps with your setup of your truck’s engine.

Please provide either a description or photos of your dashboard and your engine with distributor. The Pierce Trucks are quite rare, so most of us have not seen any, even in photos or magazine articles.. The more we know, the better we can help you. The trucks often used parts and systems from the cars, and often from ‘left over’ parts supplies. So it is quite possible that someone, looking at a photo you post here, will see that the odd, or spare part on their shelf might work or is THE right part for your truck.. But by written description alone, it will never happen.

Greg Long