Where to look if G model tach no worky?

[Jemal]

Hi all,

Kinda new to my 911, well known for my Classic Mini Cooper builds (lots of practice with British wiring), my 76 with a 78 3.0 SC engine has a non functioning tach.

Does it need to be removed or can I check a few things first? Where does it get it's signal? No apparent wire from distributor or coil?

Can it be accessed from the frunk? looks like quite a reach...

[shadowjack1]

The tach can be removed from the drivers seat. Just pry it out. But first you need to remove the steering wheel, at least on my 88'. Check the two wire in the tunnel, access thru the panel in the rear seat. The panel is on the floor and held in by four screws. It's between the seats on the floor.

[jbell959]

The connections in the tunnel are for the speedometer not the tachometer. Your tach wire is black/purple and is in the main harness that runs through the tunnel. I'm assuming a 6-pin CDI box was also installed when the engine was swapped. Your tach signal should be coming from the CDI box. You need to confirm that it was wired correctly in the back because on a 76 the tach signal would have come from the points.

[Jemal]

A good start thanks... I'll look for the wires in the tunnel. On most cars of the era, the tach pickup is readily apparent on the coil negative. If they're in the tunnel I'll try to follow them backwards.
Yes has the CDI and electronic one wire distributor, but I'll check the black/purple and connection to the CDI for the tach... good info!

[timmy2]

Black/purple Tach wire is accessible in the engine compartment at the white 2 way “T” connector that also supplies power to the CDI.
Black/purple from 6 pin CDI needs to be routed there when installing in a 76.
It normally runs back in the harness to the 14 pin connector from 78-83.

And, for the air flow safety switch to work and turn off the fuel pump, the brown/red that runs to the white T connector in an SC harness, now needs to be run to the single plug brown/black wire that hangs out just below the 14 pin male plug.

[kent olsen]

Hey Jemal, It's Kent from Oregon

So now you have a classic Porsche with your Classic Mini. Enjoy

Front engine front wheel drive a little different going around a tight turn than rear engine rear wheel drive. Have fun.

[Jemal]

Hi Kent
Did you get your Mini sway bar sorted out? And yup. my first rear engine car! But I'm having the most fun driving the 71 Midget I built in the last year or so... amazing how much fun without that much power! Of course I've made serious upgrades to suspension and brakes.

Not driving the 911 even tho I have it running great. I'm stalling somewhat, hoping to avoid California smog check for my 76 (with a later 3.0 and broken off smog pump)... There is legislation in the works to move the smog requirement to 1983, by which time almost all cars sold had fuel injection. There are so few people left who can work on carbs that it's getting technically impossible to test the old cars. And so few old cars that bovine flatulence causes more emissions!

[kent olsen]

Yeah, I'm a carb guy. Weber's on the 911, dual AFB's on the Hemi/Vette, and SU's on the Mini.

[megerian]

I have seen the tach removed without removing the steering wheel (on an 88) by having one person lift up on the front edge of the dash, while the other person pulls out the tach.