Tachometer help. Where do I connect on 6.4 stock crate harness?

[Flchallenger]

Putting a 6.4 in a 71 challenger. Got a crate motor from dodge a stock wiring harness and ecm. There is no dedicated tach wire. So how do you connect a tach. I have a new auto meter tach.

 

[Katfish]

I couldn't find anything, ended up getting a cheapie ODB2 tach to plug in.
Please post what you find, I had zero luck.

https://board.moparts.org/ubbthread...true/re-tach-for-gen3-motors.html#Post3249161

 

[Challenger RTA]

Don't know if this is a help. 2012 diagram. 19 bottom right. You might need a tach adaptor. Different signal?

 

[Flchallenger]

There is 8 ignition coils are there not? The diagram I think will help tremendously. Thanks

 

[Flchallenger]

I went and did more research. I have a auto meter tach and they have some adapters. But it looks like wire 19 in the schematic maybe I connection point. I am checking with there tech support tomorrow.

 

[pschlosser]

pin 19 looks ominously like the legacy tachometer line. I would try that one, first.

 

[Katfish]

I went and did more research. I have a auto meter tach and they have some adapters. But it looks like wire 19 in the schematic maybe I connection point. I am checking with there tech support tomorrow.

Yep, they want you to tap into all 8 of the coil packs to an adapter, too much trouble IMO
Wasn't going to cut into a brand new wiring harness 8 times, crazy.

 

[Flchallenger]

I don't want to tap into 8 coil packs either. There has got to be a better way.

 

[Flchallenger]

I think I am going to try to GMR pickups on opposing cylinders . I can change settings on my tach to a 4 cylinder. MSD suggested that this might work.

 

[scar426]

So for 2 of my swaps, I used an MSD GMR tach adapter, clamps over 1 coil wire, ran to tach (Speedhut tachs) and switch power, ground, easy peasy works great. On my current Cuda 6.4 swap tried same thing, but with Autometer gauge (tried 2 different) doesn't work. My guess is the gauge. (1 autometer gauge didn't have a dip switch setting for single pulse as required by MSD and the other did, but still wouldn't work properly) At some point I'll bite the bullet and swap to a Speedhut tach. No splicing required with the MSD GMR pickup adapter.

 

[Katfish]

Interesting, wasn't familiar with Speed Hut.
Looking at website, they have ODB2 versions, so if buying a new tach, why bother with an adapter.
I need to measure the size of the factory tach, they just might have a size to fit.
At the moment I have an ODB2 tach zip tied to steering column, works great, but would be nicer inside the factory spot.
I would however lose the other functions, voltage, temp, clock, error codes etc.
It would be perfect if round, but has weird shape.
And only $40, not $300-$400.

https://postimg.cc/YjL2mvFB][/url]

 

[Flchallenger]

Well looking at a auto meter tach it shows hooking to the coil or msd electronic ignition box. Some wondering if one GMR will work.

 

[sixpactogo]

When I installed a 6.1 in my 68 Charger back in 2015, I'm pretty sure you just need to tap into one coil pack. I chose # 8 because it was closest. You could contact Chris at Hotwire Auto. He would know for sure.

 

[Katfish]

Where you guys mounting the tach?

https://postimg.cc/8jr7PMr1][/url]

 

[scar426]

my dash was already changed out to an Autometer set up, in the rightside 3 3/8 hole. The single msd gmr works fine with the speedhut gauge, just not the autometer that was in the car. So,
I bought a different autometer gauge that is supposed to work with the MSD GMR single pulse setting but does not. (I think initially it did for a few days but no longer does)

 

[AUSTA]

Crank position sensor no good ?