MSD Tach Help

[Bubba7696]

I have a 72 Mustang mach 1, i just recently installed a MSD 6AL and a MSD Blaster 2 Coil. Distributor has a Pertronix ignitor kit in it and it is the factory Tach. The tach was working perfect before the MSD box installation. The tach will read about 200 at idle and slightly go up to 300 when running. The grey wire from the MSD is not connected to anything. There was a red/pink (not sure what color) in the factory harness that was connected to the (+) side of the coil (Believe to be the ignition wire). Disconnected that and connected it to the red wire from the distributor and the red from the MSD. Not sure where to go from here. Where the grey wire connect and do i need a tach adapter from MSD? I have no clue what the wires look like for the tachometer or where to find them in the engine bay.

Thanks for any help.

 

[DK73]

Well I say that it is the MSD..

Sent from my E2303 to Tapatalk

 

[c9zx]

Search on "current triggered tach mad 8920". Chuck

 

[Bubba7696]

Search on "current triggered tach mad 8920". Chuck

So I will for sure need the 8920 adapter?

I'm sorry I sound so noobish on this.

 

[turtle5353]

If your running the msd with stock tach yes. If not you can send your tach out to rocketman and have it converted to work with the new msd. That's what I did with mine.

 

[Bubba7696]

Do I need to do anything with the ballast resistor?

 

[MeZapU]

Just leave the factory tachometer trigger wire T'd into the MSD box trigger wire(white) and the (black) wire from the Pertronix. Do not use the tach output (gray)from the MSD box.

 

[Bubba7696]

I've been told there is a flat 4 pin connector coming out of the firewall and the second is the tach trigger wire. I believe it's red with light green striping on it and I have it tied in with the red wire from MSD and orange from distributor ignitor. If I unplug it the car will not start, just crank. Which leads me to believe that's not the trigger wire but the 12V ignition switch. By factory harness does the tach trigger wire have a plug on the end of it?

 

[72HCODE]

msd needs the tach adapter

 

[Bubba7696]

Alright, thanks guys. Ill let you know if it gets working when i get the part.

 

[Don C]

msd needs the tach adapter

+1. Ford wired the tachometer in line between the ignition switch and the positive terminal on the coil. The stock tachometer will not work unless it is connected to the coil, or the MSD adapter. The ignition wire runs through a coil/transformer in the tachometer that transfers the pulses from the ignition coil into the tachometer electronics, no pulse no tachometer. The other option, already mentioned, is to have Rocketman convert your tachometer so it operates like aftermarket tachometers.

The pink wire that is between the tachometer and ignition coil is the ballast resistor. You'll have to read your instructions to determine if your box needs full battery voltage instead of the reduced voltage from the pink resistor wire.

 

[Bubba7696]

msd needs the tach adapter

+1. Ford wired the tachometer in line between the ignition switch and the positive terminal on the coil. The stock tachometer will not work unless it is connected to the coil, or the MSD adapter. The ignition wire runs through a coil/transformer in the tachometer that transfers the pulses from the ignition coil into the tachometer electronics, no pulse no tachometer. The other option, already mentioned, is to have Rocketman convert your tachometer so it operates like aftermarket tachometers.

The pink wire that is between the tachometer and ignition coil is the ballast resistor. You'll have to read your instructions to determine if your box needs full battery voltage instead of the reduced voltage from the pink resistor wire.

Thanks Don, that made a lot of sense, do you have any experience with the Rocketman Conversion?

 

[Don C]

No, I don't, but a lot of forum members have and are very happy with his products.

 

[Hemikiller]

The 8920 is the correct adapter to use for the MSD. Have used it on several cars with good results.

The correct wiring setup is on pg 2 of the manual

http://documents.msdperformance.com/8920.pdf

 

[Bubba7696]

I have the red-light green wire from the firewall, the red wire from the distributor, and the red wire from MSD all tied together right now and when I get the adapter,

I tie the red one from the adapter to the other 3?

 

[MeZapU]

Why is everyone concerned with the tach adapter? It is not needed if the pickup to the tachometer is from the pertronix itself. I use this method all the time and even used it to trigger my FiTech EFI system.

 

[jbojo]

msd needs the tach adapter

+1. Ford wired the tachometer in line between the ignition switch and the positive terminal on the coil. The stock tachometer will not work unless it is connected to the coil, or the MSD adapter. The ignition wire runs through a coil/transformer in the tachometer that transfers the pulses from the ignition coil into the tachometer electronics, no pulse no tachometer. The other option, already mentioned, is to have Rocketman convert your tachometer so it operates like aftermarket tachometers.

The pink wire that is between the tachometer and ignition coil is the ballast resistor. You'll have to read your instructions to determine if your box needs full battery voltage instead of the reduced voltage from the pink resistor wire.

Thanks Don, that made a lot of sense, do you have any experience with the Rocketman Conversion?

I had the conversion done and use the tach output from the MSD box. Works with no issues.

EDIT: I am using the MSD distributor but should not make a difference. If I remember correctly I was also provided a jumper'd connector that you will need if you do this conversion. Here is the wiring diagram that you would need to follow.

http://www.rccinnovations.com/Instructions/OEMTach.pdf

 

[Don C]

Why is everyone concerned with the tach adapter? It is not needed if the pickup to the tachometer is from the pertronix itself. I use this method all the time and even used it to trigger my FiTech EFI system.

See my Post #11, Ford did not use a tach pickup signal like most other tachometers.

 

[Henry Ford]

WHOA! How many of us complain about buying a car that has a butchered wiring harness? NEVER CUT FACTORY WIRES!

the last .PDF is to install an aftermarket "STYLE" 3 wire tach.

the FORD 2 wire tach is best left in place and use the MSD tach adapter as stated.

Every time a wire is cut many little electron will never find their way home.

( and mystery gremlins start haunting your ride)

MSD 6 AND 6AL are easy to wire and can be dropped in stand alone just requiring a a few connections without cutting wires. Always when you can find an appropriate extra mating connector and butcher that baby. If there is a sudden failure of the installed non Ford components you can quickly revert back to the factory setup.

(carry spare points and condenser in the glove box + screw driver and feeler gauge)

6,500 + rpm with Blue streak Points - no regrets.