Tach harness pigtail question -

[Daddy'O]

OK – I think I already know the answer but I would like confirmation.

We are upgrading my son’s truck with a new instrument cluster which has the factory tach. His truck has HEI. We have the tach harness for HEI.

My question as silly as it will sound is this: The pigtail on the pink wire – is this just a means of allowing more than one harness to utilize the ignition unfused power point on the fuse block?

Many thanks!

[Daddy'O]

ttt

VetteVet, fixit-p - I'm I correct regarding the pigtail, or does it serve another purpose?

Appreciate your inputs.

Thanks!

[VetteVet]

I'm trying to picture what you have there and I can't decide if it's a power wire for the tach or something for the HEI. They could be using it for the tach power off the HEI bat terminal, but I wouldn't feed any load frrom an ignition wire. It doesn't seem likely that any harness would use the ignition un-fused by just plugging into the fuse panel.

This picture shows one of the forum members using the fuel gauge pink wire connection to power the tach but he still has to have the wire to the distributor
for the tach to dash cluster connection.Where does the pink wire go that the pigtail attaches to?

[Daddy'O]

VetteVet,

Sorry that I wasn’t very clear with my question.

I have this wiring harness for the factory tach and a HEI distributor:

http://www.classicparts.com/1968-72-...tinfo/52-846B/

If you are able to look at their photo you will see the V connector (brown and pink wires) which go to the tach. The single brown wire goes through the firewall to the HEI. The single pink wire connector will be plugged into the ignition un-fused spade in the fuse block. My question is why that particular pink wire has a pigtail?

I actually took a better picture of our harness – unfortunately it’s on my PC at home – where I currently am not.

I hope this gives you a better understanding of my question.

Many thanks!

[VetteVet]

That helps, I think I may have figured it out. What you have is a tach harness IF you have an HEI distributor and not to power the HEI and the tach. The brown wire is for the tach terminal and the pink wire is for the power on the tach. It goes to the ignition unfused on the fuse panel. The short pigtail is is for the HEI power to the BAT terminal on the distributor. You may need a separate wire for the tach light if it has one.

Usual disclaimer applies LOL

[Daddy'O]

Thanks VetteVet –

So to clarify, the pink pigtail we are discussing is really nothing more than an additional ignition un-fused power point. Correct?

If one was using another means to provide power to the HEI distributor BAT terminal as say with a modified engine harness picking power where the old orange/purple starter wire was, then one could safely use this pink pigtail to say power an electric choke? Or say use it to plug the air conditioning harness to (which also has a similar pigtail)?

Sorry to be beating this to death. I want to be able to confidently explain this to my son as I’m doing my best to show him the correct way to do things as well as explain why we are doing them.

Thanks again for taking the time to help.

[VetteVet]

So to clarify, the pink pigtail we are discussing is really nothing more than an additional ignition un-fused power point. Correct?

That's what it seems to me. At some point in time I'm going to research the possibility of cutting the ignition resistor wire off about 2 inches from the firewall block and checking it for voltage drop. If it is negligible then that would make an excellent place to splice the Hei power wire. The proper way to do it is to separate the firewall block and install a new terminal and wire but it's more work. I'm not convinced that a good splice wouldn't work just as well if there was no voltage drop.
The ignition un-fused terminal is not really made for a junction block and I would fuse any load connected there because it is not fused except by the fusible link way back by the battery.
I applaud you for working with your son, It's a bond that you'll treasure, as will he. I know this from my example.

[Daddy'O]

Thanks VetteVet -

Understood about the inline fusing for loads. Speaking of which – can you recommend a good fuse rating for the positive wire to an electric choke on an Edelbrock carb? My google search indicates a 5 to 7.5A fuse – seems like a large fuse for a small wire.

Again - thanks for the confirmation and kind words – I appreciate it.

[VetteVet]

I'd use a 10 amp with a 16 gauge wire. The fuse has to be larger than the load or it will blow all the time. Most electric chokes come with 18 gauge wires and recommend a 10 amp fuse. Here's a website to read.
http://www.hotrodders.com/forum/ques...ke-156733.html

[Daddy'O]

Thanks for the link –

Good information. Didn’t realize the initial current draw could be so high. Definitely learned something today.

The PO obviously had some issues with the choke as the positive lead is missing and a zip tie is restricting the choke. I will use your suggestion of a 16 gauge wire with a 10A inline fuse when we get to the fine tuning of the carb.

Thanks putting up with me today.