For my '65, I purchased an original-type, in-dash tach (will be mounted in the blank/clock space) from The Parts Place, which I have not installed yet but would like to. I do have my electronic ignition (not HEI) from Summit installed. My ignition has the separate coil and normal diameter distributor, just electronic instead of points (Summit SUM-850400-1). From what you are saying above, it sounds like I can connect the "original equipment" tach, the same way I would if I didn't have electronic ignition, and things should be ok. Is that what you are saying or am I misunderstanding. I've been getting mixed opinions on this, just wondering if anyone has done this and whether there were any issues.
Yes, it should connect right up like any tach with a points type distributor. I did the Pertronix I electronic conversion to my '68 points distributor and hooked up the aftermarket add-on tach to the coil with no issues. I used 12 volts going to the coil versus the 7-8 volts used with the resistor wire.
The factory wiring diagrams seem to show a 1 AMP inline fuse used on the wire going to the coil. I personally have never seen one, but the cars I owned "way back" were beat and good possibility that were long removed. So it may not hurt to protect your tach with the inline fuse.
In doing some more research, it seems to be a mixed bag as to what to expect from the tach with electronic conversion. Most say no problems, others do have accuracy problems. It could be that if you switch to a direct 12volt power source to the coil instead of using the factory resistor wire, you could have too much voltage going through the factory wire coming off your tach and make it act up. You may need to add a resistor to the tachometer lead
(not the 12volts going to the coil if you are using 12volts), but being an aftermarket tach, you may be OK.
Just to give you an idea of what may need to be done, this is what Pertronix suggests if your tach gives you problems. You might use it for reference with regards to your set-up. A ballast resistor might also do the job and these are sold at Summit as well. http://support.pertronix.com/file.ph...50ad853083634b
If still uncomfortable, I would email Summit as well as the in-dash tach suppler and confirm what it is you are using and they should be able to give you a definite answer.