Tachometers - Installing tacho in 1968 V8

Eric

Member
I intend to try installing a TC tachometer into a Series one V8 equipped with Pirhana electronic ignition. I intend to adjust for electronic ignition by, if necessary, altering the number of turns on the inductive coupling inside and I will also try to recalibrate for 8 cylinders using the variable resistor behind the rubber plug. I have found all this information from the internet. What I can't find is, of the three connections on the back of the tacho, which goes to the distributor? Which to the ballast resistor?, and, which to the ignition circuit?
Has anyone tried this or should I stop now!
 
Eric,
This sounds very technical and could form the basis of an informative article for the P6 NEWS.
Please, if you find the answer, consider submitting a few words to our worthy editor.
Regards, John.
 
John,
Thanks for your suggestion. After posting the tacho questions last November and receiving no replies I decided to live with it unconnected and just cosmetic. I'd read on a Sunbeam Alpine site that the 4 cylinder smiths tacho could be adjusted for 8 cylinders (the Sunbeam Tiger) using the calibrating potentiometer under the rubber plug and a connected up separate accurate rev counter. I was also advised how to adjust the tacho to work with electronic ignition by reducing the windings on the coupling if necessary. However after looking for months, I found the correct rev counter for the V8, and so the job has become easier although I still don't know yet which of the connections goes to the distributor!
I will connect it soon and let you know. If a 4 cylinder TC rev counter could be easily recalibrated to 8 cylinders then that would clearly be very useful to members given the attractiveness of the add on "pod" and the relative abundance of TC tachos.
Thanks for your interest,
Eric
 
Eric,
My 1968 Three Thousand Five (strip speedo) has the tacho and clock mounted in a binnacle next to the speedo and, judging by the red line position, the tacho is originally from a 2000TC model. Hence, 4 cyl can be used on 8 cyl.
Done by a previous owner and all wiring behind tacho is in black coloured cable so I've no idea how he did it but it works so I'm not going to tamper with it (unless I can obtain a V8 tacho with the red line at the right place).
Regards, John.
 
Dear Eric,
I am bidding on e-bay for a tacho correctly calibrated for the V8 engine - If I'm lucky (?) enough to win this I will attempt to fit it in place of the Rover 2000 TC one which I have presently fitted in my car.
Will let you know how I get on.
Regards, John.
 
John, Good luck with your search. I bought my V8 tacho on Ebay. The connections were simpler than the TC one as the wiring was more obvious, with the coil to distributor loop going through a coupling externally rather than inside the tacho case. I've now connected it and it looks and works beautifully and it did need some adjustment through the rubber plugged hole in the back. Having the wrong 4 cylinder tacho fitted has been more irritating than I thought it would be even though thats the one pictured in the parts book. The question for me now is whether to put a chrome bezel on it to match the clock rather than the plain black that originality demands. I suppose most P6 enthusiasts have to decide whether to restore to what was originally available or to "modernise", eg power steering in a 1968 car ,electric fuel pump and ignition, two pack paint etc? (this is true anorack land).
Eric
 
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