Tachometer questions.

[bullet18]

I can't seem to find much info on how to install a tach on my motor. Ive got a 78 motorhome 440 in my 70 challenger with a chinese hei knock off distributor. My dash doesnt have a tach but i would like one so i can set total timing and not accidentally float the valves. Where do most aftermarket tachs get wired to? The coil?

 

[Rich G.]

Negative side of the coil

 

[Adam]

On a factory equipped tach car there is a gray wire from the bulkhead connector to the coil. The wire is in spot #20 (probably vacant on yours) and you can run a wire from the same slot on the inside, to the tach, if you want.

http://www.mymopar.com/downloads/1970/70ChallengerRallyeclusterdashA.JPG

 

[aussiemark]

The after market tacho will or should come with some instructions (if new) there will be wiring for illumination you will have to wire this into your light bar so it comes on when you switch the lights on. there will be negative to ground, positive to switched power and negative trigger to the negative on your coil.

 

[moparleo]

I don't believe that the 70-71 Rallye tach's will work with electronic ignitions as Chrysler was still running point ignitions until 1972. An adapter is required. Need more research.

 

[Adam]

The Mopar electronic ignition & distributor do work on a 70 & 71 cars with a Rallye tach. 100%, I have personally done this on both my cars, with no adapters. The coil does not know what type of dist is triggering it, and the tach gets it’s signal from the coil.
I do not know if the MSD or other aftermarket spark systems work with the factory tach, I suspect they do, but I have never used them.

 

[bullet18]

Thanks for all the info! I guess i can just use an aftermarket tach.

 

[AUSTA]

If using aftermarket source 1 with settable high rpm trip point so that you can connect a light or if you fit an MSD at later stage you can set RPM limit

 

[bullet18]

If using aftermarket source 1 with settable high rpm trip point so that you can connect a light or if you fit an MSD at later stage you can set RPM limit

Will do. Thanks!