HEI tach vs Non HEI tach
 

Ok I see repro tachometers for sale. What is the difference between the HEI versus non HEI tachometer.
Thanks

Re: HEI tach vs Non HEI tach
 

I am no expert but I would say it has to do with whether you have a regular distributor or a HEI distributor.

Re: HEI tach vs Non HEI tach
 

The signal from a standard points type distributor is different than the signal from an HEI distributor. This link explains it. http://www.americanautowire.com/view...c-distributor/

Re: HEI tach vs Non HEI tach
 

Just for GM..........HEI is GM's electronic dist., coil in cap, with simple 1-wire hookup--to always hot with key turned to "ON" or to "CRANK"--began widespread use in 1975 and newer GM cars. Reg. dist.[non-HEI] is from older GM cars--1974 and older--having points, external coil, and usually a ballast resistor in series w/the wire going to + side of coil. The HEI puts out much higher voltage to plugs, carries bigger wires, and uses electronic module instead of points/condensor. Both use a rotor button to distribute the fire to the individual cylinders. HEI allows for wider spark plug gap for more complete combustion. Only function of condenser in HEI is for radio noise suppression--nothing to do w/ignition. And, yes, you can replace older points type(reg. dist.) with HEI and gain much joy.
HTH,
Sam

Re: HEI tach vs Non HEI tach
 

Thanks for the replies. I do know the differences between standard and HEI distributors. My question is what if any difference is there on the repro tachometers some are listed as for use with HEI and some do not. I called supplier and they said they did not know if the repro tach would work with HEI. I have both types of distributors so I guess I was just wondering if there is a difference on the wiring to the tach between the two.
Thanks

Re: HEI tach vs Non HEI tach
 

I'll be honest, I did not know there was a difference in a tach between HEI and non-HEI All the tachs I have or seen in use worked with either distributor.

Re: HEI tach vs Non HEI tach
 

Don't quote me but I think it has to do with filters built into the tach to prevent damage to the gauge or due to voltage issues. I know a buddy was looking at repo tachs and there was non HEI only available and he is running an HEI so he went a different route as he did not want to chance any damage.

Re: HEI tach vs Non HEI tach
 

Re: HEI tach vs Non HEI tach
 

Yeah neither did I. I have a new sun pro super tach 2 and it says it's universal on the packaging, it works fine with my 261 with points.

Re: HEI tach vs Non HEI tach
 

Sorry it is hard to gauge the level of knowledge sometimes. I know vary little so I wrongly assume that the same is true of others.

Re: HEI tach vs Non HEI tach
 

Yeah, most of the aftermarket tachs have the built in circuits to deal with points or HEI. It's the factory style dash tachs that have issues.