3.2 conversion Tach wiring

Electricguru · 11-18-2005, 09:45 AM

Anyone know how to wire a 1987 tach in a 1976 car. Its for 2.7 to 3.2 conversion. I put the same numbers back from the old tach to the new, but still have unused terminals.

1972_911T · 11-18-2005, 10:23 AM

Im currently doing 3.2 into my 72, I found on the 3.2 there are two wires from the DME for the tach one is black (I think) and the other is black/purple as was the early wiring. From my research you use the black/purple from the DME to the tach gauge and just tape the other one off unused. Never managed to find the purpose of the other tach wire yet.

Anyone know?

Steve

1972_911T · 11-18-2005, 10:26 AM

Sorry just re read your post and notice your using the later tach, Y you change it im sure the early tach's will still work with the 3.2?

Electricguru · 11-18-2005, 11:23 AM

The earlier tach does work!! Thanks for the help!! I used the black/purple wire. It goes on the #2 terminal while #1 and #3 stay on their terminals. The existing #2 wire is not needed.

Thanks Again

larrym · larrym's Garage

new issue - worth knowing about

apparently our older tachs can eventually "fry" the DME, even tho they seem to work

914 3.2 conversions -

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wiring diagram for 3.2 tach here
Tachometer tap 3.2

ischmitz · ischmitz's Garage

If you wire the shift light output from the DME to the tachometer input you will damage your DME. I had to repair this multiple times.

larrym · larrym's Garage

Quote:

Originally Posted by ischmitz

If you wire the shift light output from the DME to the tachometer input you will damage your DME. I had to repair this multiple times.

the problem identified & described in the link <914 3.2 conversions> above is different from the well-known shift light goof-up

DME is NOT REPAIRABLE

whereas you were able to repair yours after the multiple goofs

.

ischmitz · ischmitz's Garage

The DME is repairable no matter what broke. It all depends on having access to the right parts. What Mark E. was told by Steve W. is unfortunately mis-information. I did repair three units for Steve in the past.

There is no issue whatsoever using an early tachometer with the 3.2 DME. The ONLY issue arises when the shift light output gets hooked up by mistake to the tachometer. And I can modify any 3.2 DME to prevent this from damaging it.

Ingo