Tach problem, '74 Euro Carrera

fkennette · 07-03-2003, 10:55 AM

I've recently acquired a '74 Euro spec Carrera w/ a regular 911T engine/tranny. I'm trying to sort out the gauges (only the oil pressure worked when I bought the car) and I'm a bit stumped w/ the tach.

The Blk/blu wire from the tach is loose in the engine compartment w/ a spade connector on the end (good continuity to this point). It is not going through the regulator panel (ie. the 14 pin connectors). The tach is getting power and has a good ground. I've used a jumper wire from the Blk/blu to coil terminals and distributor side w/ no results.

I see that some of the wiring diagrams (none of which are perfectly accurate for my car) show an RPM transducer or similar device, and of course I don't have one. Should the wire be connected to the ignition box instead? If so, where?

Thanks for any help you guys can provide.

Francis Kennette
Belle River, Ontario

Paul Thomas · 07-03-2003, 11:12 AM

Unless i am mistaken, the T has a points type tach and the Carrera has an electronic one. are you sure that you have the right tach for the motor? I had to switch tachs when i put the later motor in my T body.

Paul

fkennette · 07-03-2003, 11:19 AM

Paul

How do I tell the difference between an electronic and points type tach?

Thanks,
Francis

Early_S_Man · 07-03-2003, 11:31 AM

Francis,

ALL '73 thru '77 Carrera 911's used points-type distributors and tachs!!!

Hopefully ... you only connected the Black/Blue wire to the low (ground) side of the 'coil' ... as the high [460 Volt, CDI pulses] side could fry your tach!!!

It certainly would be safer for your instruments ... had you taken a bit of time to figure out from the '73 - '77 schematics that the tach only needs to be connected to the distributor points to get the proper signal!

Paul Thomas · 07-03-2003, 06:30 PM

It turns out i am mistaken, they didnt change that until 78. My apologies.

Paul