69' In-Dash Tachometer Compatibility with MSD Ready-To-Run Distributor

[james1969 10]

Hi,

 

I've got a 69' fastback with a 351w. The previous owner installed an MSD 8354 Ready-To-Run distributor and a Blaster 2 coil. The OEM in-dash tachometer was disconnected at that time.

 

To reconnect the in-dash tach, I believe I need a MSD tach adapter (8920 or 8910) but am unclear as to which one. In addition, after scouring MSD's website, I cannot find installation instructions for the tach adapter between the 8354 distributor and Blaster 2 coil (all seem to also require the MSD Ignition box which is not necessary when using a ready-to-run distributor).

 

Have any of you had luck getting your original in-dash tachometer to work with only an MSD ready-to-run distributor and coil?

 

Thank you for your time and input.

 

Best,

 

James1969

[ashleesmach1 28]

it won't work with the indash tach due to the way the tach was originally wired. Do some research on the in dash tach. I do not remember why

[PaleRider 12]

Not an expert by any means but have a msd ready to run, igniotion box, tach adapter, and had an external tach on 1 car and had in dash tach and pertronix on another. Both 1970s. I don't think you need an adapter unless your are running an igntion box. I know I did not on the external tach car until I added the igntion box. For the internal dash you can run another wire from tach bypassing factory wiring. You will need to deal with the point that factory tachs are wired thru car ignition. A lot of times they have been bypassed/jumped. If the tach is fried the car won't start if not bypassed/jumped. Good chance yours is and will need rebuilt. Do a search on my threads and tach - was a post awhile ago troubleshooting in dash tach and wiring.

Edited April 28, 2011 by PaleRider

[danno 128]

The factory tach was not really a tach, it was a current (amps) meter. It measures the current from the ignition switch to the coil. The higher the engine speed, more sparks sper second are required from the spark plugs. To get more sparks, it takes more current in the wire from the switch to the coil. So Ford put an ampmeter in the wire and called it a tachometer. It is very accurate and works fine, until people started changing ignition parts.

 

The factory tach should work with aftermarket distributors and coils. There is a chance it will not be accurate, though, with aftermarket parts. A high voltage coil might mean more amps of current than a standard coil, and so the tach always reads a certain percent high.

 

So it will definately not work with Pertronix or other aftermarket ignition systems. These are what you need the convertors for.

 

Something Ford never did, that is a wise thing to do, is to add a fuse in the line to the factory tach. If your coils shorts out, it could ruin the tach. Maybe that happened, which is why it was bypassed?

[PaleRider 12]

I ran a pertronix and factory tach w/o an adapter - take a look at the post - only difference to what I posted is that I ran a 12v coil.

 

http://www.1969stang.com/mustang/forum/showthread.php?t=5910&highlight=tach&page=2