Need advice on MSD TACH ADAPTOR

[Wietse]

Gents,

I need some urgent advice on a tach adaptor to install for my tic toc tach on my '69 Coronet 440.
Recently a Ready-To-Run MSD 8287 distributor and a MSD Blaster SS coil 8207 were installed which is working very good btw.
Obviously the issue as many others found is that the tach is no longer working properly, at idle it moves a bit but at higher rpm does not work at all.
So, i need a tach adapter.
Problem is it is not clear to me which one i will need, currently my ignition 12V supply comes directly from the battery through a relais and the ballast resistor is no longer used in the power supply to the coil and has a constant 12V.

Do i need the 8910 or 8920 adapter?
The RTR distributor has a grey wire to hook up a tachometer trigger wire.
As in all installation manuals i've seen the take a MSD 6 type module as an example on how to install but this does not make me any wiser on how to do this on the Blaster SS coil combined with this type distributor.
Same as on here and many other forums the info asked and given are for the systems with separate control modules which mine is integrated in the distributor.

The 8920 model mentions that this should be used for models that use the magnetic pickup input to trigger the MSD ignition, i have no idea how to reflect this type of operation on the RTR unit i have.
The 8210 mentions it is designed for non-current limiting ignitions, which i believe mine is as the ballast is no longer used.

I am planning to order a bunch of stuff from Classic Industries and i want to implement the required tach adapter together with a new tic toc tach to get everything back to working order.
Thing is that due to long delivery times i want to make sure that i get the right stuff in the first order as sending it back for exchange will take a long time.

If you know or run same equipment please let me know which adapter i will need.

Thx for reading!

 

[SwedCharger67]

Do i need the 8210 or 8910 or 8920 adapter?

Just for your info I'm using the 8920 adapter having my engine management system (MegaSquirt) driving the original Charger 1967 tach. It all works well...with one significant drawback...the 8920 unit is emitting a fairly loud, and annoying, buzzing sound.

I will replace the MSD 8920 with a home-made solution...you might search for "megasquirt tach adapter" to see pictures of a simple solution. It should work with any electronic ignition outputting a digital tach signal.

 

[Wietse]

Hi Swedcharger,

Thx for the info.
I can only assume the signal given from the grey wire of my distributor is a same type signal as given from a separate ignition module.
Looking at the installation instructions it looks like the 8920 would be the one to use for my application as that one has a separate input from the MSD system and a separate output for the tach wire.
The 8910 is installed like an "in-line" unit which i believe cannot be correct.
I already contacted MSD and asked the same question but i have had no answer from them for the past 4 days.
Hopefully someone els can chime in and confirm this.

So if this is the unit to go i should install it somewhere in the engine compartment and not under the dash to keep the annoying sound away.
Good tip to know!

 

[Wietse]

Now i've installed and tested everything properly i wanted to leave my findings on this issue for any future reference.
I ordered the 8920 Tach adapter to see if this sorts out my tachometer issue, which it did.
I also ordered and installed a new reproduction tachometer from OER and everything is working fine.
So, when you install a MSD Ready-To-Run distributor also add a 8920 Tach Adapter to properly convert the signal so you tachometer works properly.
Might help someone out in the future i hope.

 

[BeeKool]

I took a screenshot of the above. It will definitely help my build in the future.

 

[Wietse]

Only a little side note that i just noticed to be wrong, i mentioned the part number 8287 for the RTR distributor.
This should be part number 8387.

Good to know it helps someone out!

 

[Cyty Slykers]

Now i've installed and tested everything properly i wanted to leave my findings on this issue for any future reference.
I ordered the 8920 Tach adapter to see if this sorts out my tachometer issue, which it did.
I also ordered and installed a new reproduction tachometer from OER and everything is working fine.
So, when you install a MSD Ready-To-Run distributor also add a 8920 Tach Adapter to properly convert the signal so you tachometer works properly.
Might help someone out in the future i hope.

I’m going through this same process now as I too have the entire msd set up and wasn’t sure which adapter I needed between the 8920/8910. I was told the 8920 is the correct adapter but now my question is did you have to replace your circuit board inside your Tach? I purchased a brand new Tach from 521 restorations and curious if this needs to done in order for the tach to function properly.

 

[Wietse]

I did replace the tach circuit board with a modern version, don't remember where i bought it from.
In the end i replaced it with the OER because the clock did not work and when trying to dismantle it to see if i could repair i realised i couldn't.
I am quite sure the new type circuit board works the same as the old version, but just with new modern components.
You could ask 521 restorations if they did something on the old circuit board, and if they did will it work with the tach adapter?

 

[Cyty Slykers]

I did replace the tach circuit board with a modern version, don't remember where i bought it from.
In the end i replaced it with the OER because the clock did not work and when trying to dismantle it to see if i could repair i realised i couldn't.
I am quite sure the new type circuit board works the same as the old version, but just with new modern components.
You could ask 521 restorations if they did something on the old circuit board, and if they did will it work with the tach adapter?

Gotcha and will do. Thanks