bounceing tach after msd 8920 hookup?

[Zed Head]

Looks like "Procomp" copied MSD, but didn't do a great job.  You have a dilemma. 

You want the tach to only see current flow from the coil.  So, you might not even need the tach adapter.  If you describe the rest of the parts one of the electronics whiz's might have some thoughts.  I've not been impressed with those adapters, they often don't work even when connected like MSD says.  The tach operation is fairly simple.  Sometimes you just need to add a loop at the pickup point on the back of the tach.

[Firepower]

Yeah, well I smoked a Tech once when ghe Alternator bridge burnt out on a ‘73.  So I’m not in a hurry to try wiring it up without a tach adapter.

I understand it’s current rater than voltage based. 

[Zed Head]

34 minutes ago, Zed Head said:

If you describe the rest of the parts one of the electronics whiz's might have some thoughts. 

We need to know the parts you're working with.  Points, ZX, 280Z VR,...

Edited February 27, 2020 by Zed Head

[Firepower]

Stock 240Z.   Will be adding:

MSD6AL. 
123ignition Tune+
and MSD6290 tach adapter except as I said I have the PCE2030 (p/n PCE387.1002) which is an ‘8920 clone’.

I can add them in stages.  I’m sure I can get the first two to work fairly easily. But need advice on the 3rd -getting a stock tach to work with the above two changes.  Or should I send it back and get the proper MSD8920?

Any advice will be gratefully received.

-Richard

 

 

 

[Zed Head]

I'd send it back.  If they won't offer support, or instructions, and the wire colors are wrong, who knows about the overall quality of the part.  It sounds like a cheap ripoff, easy money for the counterfeiter.  The 8920 is about $10 more.

You might even consider the Technoversion adapter.  He gets good reviews.  Seems to make good stuff.

https://www.technoversions.com/TachMatchHome.html

 

[Firepower]

Yes.  It’s probably knockoff junk.  I found this thread which has pretty accurate wiring diagram which I can work from.  

see: 240Z-msd6al-8920-tach-adapter

I think the first trick is to bypass the ballast resistor, which I have already done.  It’s easiest to just leave it there and move one of the wires so the black/wht and black/grn are connected together.  Or you could put a jumper wire between the two terminals  

For the 8920 tach adapter:

Black Wire is Gnd

Red wire connects to the old (+) wire from the coil. (black/wht on a 240Z)

White wire to Grey wire on the MSD6AL (tach signal)

Violet wire is unused

As the PCE387.1002 has R,Bl,Or,Grn

My best guess from research is to hook it up the same way for Red & Blk and use the Green wire to the Grey wire on the MSD6AL.  Looks like Procomp use Green as their “tach signal“ color.   The Orange wire is unused.

Once it all works, I’ll document exactly what I did and post it.  Probably by buying the MSD 8920 first and sending the PCE (now Speedmaster) junk back.   Be warned, buy the MSD6AL and MSD accessories, not clone parts.  It’s not worth your time to save a few $.   I’ve since read lots of reviews saying the ProcompElectronics.com (Speedmaster79.com) stuff falls apart or stops working  

Edit: I have now sent it back and am awaiting a refund.  Not worth damaging it and having to eat the cost.  Also for the difference in price it wasn’t worth the hassle.   
I will not be doing business with Procomp/Speedmaster again. 

I have ordered the actual MSD8920 from Jegs.  At least if there is any issue I’m dealing with the same company (MSD) for both the 6AL and the 8920. 

 

Edited March 7, 2020 by Firepower
Updated