Westach tach w/ Pertronix

[Ward Duffield]

I have a 1946 Plymouth, stock engine, stock distributor, 6 volt positive ground Pertronics system installed.

6 volt positive Ground Westtech tachometer installed.

The tach worked fine with the stock points, but I don't seem to be able to get it to do anything with the Pertronix installed.

Can someone please give us a detailed scheme for connecting the tachometer when using the Pertronix module?

Thank you

[Frank Gooz]

The Man at Westech told me that his Tack will not work with electronic ignition. Not sure if there is a design change.

I thick his name was Collen 

[Loren]

I have a modified Autometer ( got it from a seller on eBay - search 6 volt tachometer ) I am using a 6 volt positive ground Delta Mark Ten CDI and it works as expected ( which is a very rare piece indeed )

The Delta Mark Ten uses points in the distributor and the Autometer tach connects at the point cable.

 

It could be that the Pertronix needs an amplifier to send enough signal to the tach.

 

There are many tachometers which use a signal from the alternator ( diesels especially since they have no ignition ) and there are some which take a signal from a hall effect sensor on the crank pulley or the flywheel ( you drill a small hole and drive in a dowel pin to provide the signal ).

 

If you want to retain 6 volts positive ground you could get a dual point breaker plate ( also an eBay NOS item but much easier to find than a Delta Mark Ten ) and that would give you good ignition and trigger the tach you have, reliably.

The best of course would be a Langdon's Stove Bolt HEI distributor ( which has a standard GM Tach out connection ) but that is 12 volt only.

So many choices and just think you can try them all if you have cubic yards of money! lol

 

Another way to get a Tachometer equivalent on the cheap is to do the math and put the shift points on your speedometer. As I recall I saw them in the owner's manual or some other Mopar publication. They were a lot lower than I expected too.

[Sam Buchanan]

58 minutes ago, Loren said:

 

 

Another way to get a Tachometer equivalent on the cheap is to do the math and put the shift points on your speedometer. As I recall I saw them in the owner's manual or some other Mopar publication. They were a lot lower than I expected too.

 

A tire calculator that includes gear ratios (listed in the service manual) can be used to derive shift speeds at a particular rpm. Here is one I like:

 

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

 

 

Edited September 19, 2022 by Sam Buchanan

[Booger]

21 hours ago, Loren said:

I have a modified Autometer ( got it from a seller on eBay - search 6 volt tachometer ) I am using a 6 volt positive ground Delta Mark Ten CDI and it works as expected ( which is a very rare piece indeed )

The Delta Mark Ten uses points in the distributor and the Autometer tach connects at the point cable.

 

It could be that the Pertronix needs an amplifier to send enough signal to the tach.

 

There are many tachometers which use a signal from the alternator ( diesels especially since they have no ignition ) and there are some which take a signal from a hall effect sensor on the crank pulley or the flywheel ( you drill a small hole and drive in a dowel pin to provide the signal ).

 

If you want to retain 6 volts positive ground you could get a dual point breaker plate ( also an eBay NOS item but much easier to find than a Delta Mark Ten ) and that would give you good ignition and trigger the tach you have, reliably.

The best of course would be a Langdon's Stove Bolt HEI distributor ( which has a standard GM Tach out connection ) but that is 12 volt only.

So many choices and just think you can try them all if you have cubic yards of money! lol

 

Another way to get a Tachometer equivalent on the cheap is to do the math and put the shift points on your speedometer. As I recall I saw them in the owner's manual or some other Mopar publication. They were a lot lower than I expected too.

I mean jeez.. all the Pentronix stuff??? from what Ive seen there seems to be lots of problems Just saying. New isnt always better

[Merle Coggins]

My Westach still works, but acts differently, after installing Pertronix ignition in my truck. The Pertronix triggers the hot side of the coil instead of switching the ground side like the points system does. I believe I still have my tach connected to the + and - terminals on the coil. At lower RPMs it seems to read low now, but when it gets spun up it seems to come into line to where it should read. I’ve double checked it with an inductive pickup tach on my multimeter. I also find that after startup the tach won’t move until I rev the engine a little bit, then it’ll settle in and show RPM, but a little low as mentioned.