Still trying to get tach working
 

I’m still struggling to get my tach working. I installed my 2.2 in my 71T. It has a Marelli distributor. The black and purple lead is connected to the contact on the side on the distributor and leads into the RPM transducer on the rear electrical panel. I know I have continuity to the tach. Since the car is a collection of bits from various cars I don’t know if everything matches. I’m not sure if the RPM transducer is right with the distributor.(see pics below) Curious thing is that when I connect a light bulb across the distributor I cannot seem to get the bulb to come on when the contact opens. The car sparks and runs fine. What am I missing. Do I have the wrong transducer. Any ideas? http://forums.pelicanparts.com/uploa...1084984579.jpg http://forums.pelicanparts.com/uploa...1084984614.jpg

Steve,

The Rpm Transducer/Speed Switch/Speed Relay isn't the problem ... that is the correct one for a carbed engine, and if it was shorted from a rusted transistor rattling around inside the case ... your ingition would have problems running!

Are you still using a stock Bosch CDI unit?

To get a test lamp to work ... try connecting it to +12 Volts and the distributor terminal, rather than across the distributor to ground.

Warren, yes I am running the stock CDI unit. However the PO was running a permatune unit with the speed switch. Would that make a difference. I put the CDI in because I knew it was a good unit and wanted to eliminate unknowns when I first started the motor after rebuild.

Steve,

No real difference of any significance between Bosch and Permatune as far as the RPM Trancducer is concerned.

The tach you have may be a unit intended for use with a ballast unit ... some/most of those tachs don't work with a point-triggered CDI system.

You may want to try building my bargain-bin tach calibrator that can also be used for such tasks as testing CDI units and RPM Tranducers ... as a pulse source ...


http://forums.pelicanparts.com/uploads/tach_calibr.jpg