Stock Tachometer with HEI distributor

Stock tachometer not working with HEI (gm style) distributor. Tach jumps around sporadically. Has anyone solved this issue before. I believe an MSD system could be made to work but I don’t want to switch out the distributor unless I have too. 

Thanks for any advice!

Stock tachometer not working with HEI (gm style) distributor. Tach jumps around sporadically. Has anyone solved this issue before. I believe an MSD system could be made to work but I don’t want to switch out the distributor unless I have too. 

Thanks for any advice!

Click to expand...

The Ford tach is a current triggered unit, and will need an adapter to be run off the TACH terminal of the HEI unit. MSD 8920 is the unit you'll need. 

https://www.msdperformance.com/products/...parts/8920

Install a DuraSpark, stock looking and MSD based their box on the DuraSpark. The right one provides ignition retard when cranking the engine.

By the way, please go to the Introduction section of the forum and introduce yourself and your car. We like pictures

Stock tachometer not working with HEI (gm style) distributor. Tach jumps around sporadically. Has anyone solved this issue before. I believe an MSD system could be made to work but I don’t want to switch out the distributor unless I have too. 

Thanks for any advice!

Click to expand...

The Ford tach is a current triggered unit, and will need an adapter to be run off the TACH terminal of the HEI unit. MSD 8920 is the unit you'll need. 

https://www.msdperformance.com/products/...parts/8920

Click to expand...

Ordered! Thanks for the help.

Install a DuraSpark, stock looking and MSD based their box on the DuraSpark. The right one provides ignition retard when cranking the engine.

By the way, please go to the Introduction section of the forum and introduce yourself and your car. We like pictures

Click to expand...

Thanks I’ll look into the duraspark. Heading to the intro section now.

There have been a lot of discussions about DuraSpark, and other ignitions, on the forum. Here are some examples

https://www.7173mustangs.com/thread-electronic-ignition?

https://www.7173mustangs.com/thread-another-duraspark-question--33764?

You can find a lot more by searching the forum. Search is under the More tab at the upper right of this page.

Stock tachometer not working with HEI (gm style) distributor. Tach jumps around sporadically. Has anyone solved this issue before. I believe an MSD system could be made to work but I don’t want to switch out the distributor unless I have too. 

Thanks for any advice!

Click to expand...

The Ford tach is a current triggered unit, and will need an adapter to be run off the TACH terminal of the HEI unit. MSD 8920 is the unit you'll need. 

https://www.msdperformance.com/products/...parts/8920

Click to expand...

Ordered! Thanks for the help.

Click to expand...

7/24/19 update:  installed the msd unit and it fixed the issue. Tach is working properly. Thanks!

RoosterMatt said:

7/24/19 update: installed the msd unit and it fixed the issue. Tach is working properly. Thanks!

Click to expand...

How did you do the connections (Wiring diagram please)

BuddyB said:

How did you do the connections (Wiring diagram please)

Click to expand...

The poster hasn't been seen here since the day he made the post.
You can go to the Introduction section and maybe ask your question there.
Mike

BuddyB said:

How did you do the connections (Wiring diagram please)

Click to expand...

He used the MSD 8920 tach adapter to trigger the factory tach. Wiring diagram is below. Connect the white wire from the adapter to the TACH terminal on the HEI unit. Ignore the MSD box setup.

This also brings up a question on how you have the HEI wired? Is it off the original coil (+) wire (red w/lt green stripe)?

Here's a wiring diagram showing the HEI distributor powered by a relay and using the MSD adapter for the tachometer.

Thanks Guys