Pertronix and Tach Problem??

[DMX]

When I installed My pertronix ignitor and a couple of other things

like new spark plug wires and a new coil my tach works funny....

When I am driving instead of staying in one spot it goes up and

down rapidly instead of staying in one spot... and at idle it is

saying I am reving at 2000 when I am only reviing at about

1200.... What is the problem.... I'm lost.....

[47silver]

hi
what year is the car? i just put a pertronix in yesterday with an msd 6al and do not have any tach problems mine is a 75 911s

[DMX]

I have a '75. ....... I have an Msd coil hooked up also...... How did

you hook your 2 wires up? Do they go straight to the coil?

[DMX]

I have been reading alot in these threads and most people say to hook

up the positive wire to a constant power source in one of the three fuses

in the fuse panel to the left of the engine.. ... Mine is connected straight

to the coil.. at first it didn't work then I went and bought a super coil and

it worked then.. .... The instructions say to hook both wires up to the coil

and the original coil would work... That was not the case....

[47silver]

on mine with msd. there were 3 wires connected to the spade connectors at the distributor.. 1 was white and i think it was the tach wire as it had a shield around it. the other 2 go to the msd i believe. i attached the black wire to these 3 wires and the red wire to the #2 fuse block in the fuse panel in the engine bay. i used waterproof connectors that shrink when heated. the car started immediately and the tach works great.

do not connect any of the pertronix wires to the coil!

gary

[DMX]

I am disconnecting the two wires from the pertronix that I have going to the coil... I am connecting the red wire to the #2 fuse in the engine bay fuse panel..... Which is the middle fuse.... The black wire I will connect somwhere along the tach wire as it runs to the coil... I hope this fix's it and works better... ... It seems to work great how I have it set up now.. Maybe it will even run better this way... I'll try first thing in the morning...

Thanks...

[DMX]

BUMPPPPPPPPPP....

Ok... I still have the tach problem.... Someone please help I am

crying over here.........

[47silver]

hi:
the black purple wire on the distributor! goes to the tach.
the black wire on the distributor goes to the cd unit "C" on the original CD unit.
Tthe white wire on the distributor goes to the CD unit "D" terminal
the blue/yellow wire on the coil goes to A on the cd unit
the white wire on the coil also goes to "D" on the original cd unit>
with the msd these connections would be the same so that the black and purple wire should go to the tach<<
gary

[CamB]

First question is "do you still have the CD unit" (silver box - looks a bit heatsinklike, left-side of the engine bay).

If so, is it being used - if it is, the "normal" way of hooking up a coil is different.

[DMX]

Gary...

Thanks I'll check that out tomorrow morning...


CamB I do have the cdi box and it is being used... How should

the coil be hooked up?


Thanks. . ..

[CamB]

Not from the Pertronix! Sorry - I actually don't know, because I have only ever installed an MSD. Same principle though.

The Pertronix triggers the CD box, which is what connects to the coil. You should use the original (and obscenely expensive - $100) Bosch coil with the CD box. Check you have the right Bosch coil as I seem to remember other alternatives aren't a good idea.

Ummm, one of the Pertronix wires (the black? definitely not the +12v one) should go to the wire from the CD box which used to carry the signal from the points.

That 12v wire from the Pertronix doesn't need to go to the coil. Both + and - on the coil should be connected to the CD unit (see Silver's post).

The simplest way to put the Pertronix is that it is a set of points, with an extra wire (the 12v red one).