250 cid firewall wiring harness layout

['68OrangeSunshine]

Originally Posted by WB72

I haven’t had time to open the manual to page 39 but will during a break.

Truck is a 72. 250 cid 3 speed on the tree.
There has been no signs of HEi, but could have been in and out again.

Thanks for the input so far guys.

Poobably never had HEI. You might think about putting it on in the future. Great upgrade.

The TCSS is obsolete. Never did much good anyway.

Keeping the Idle Stop Solenoid is probably unnecessary, but don't throw out the stuff if you're going to run a Monojet. If it runs on after shutting the key off, you will want to put it back on. Also called an Anti Dieseling Solenoid.

If you're going to an aftermarket intake, 2- or 4-barrel carb and headers, then all this old wiring is obsolete.

[WB72]

For sure it is for the TCS thanks for the diagram, Jason.

By the looks of the diagram, the temp sender on the t-Housing is to work with the TCS. I will leave it in place and remove that wiring.

This truck is being built with this drive train due to sentimental reasons. I want to have the same style of truck that I shifted my first gears on. with that being said, I also have an LS in my shop to transplant if things don't work out as planned, so I think I will delete the TCS system. i am not too attached to that. I don't think I will set up HEI since I have alternate plans in the works anyway. I did that conversion in my other 72 and am pleased with it tremendously.

As for my water neck, I may have installed it incorrectly during the rebulid of the old 250. will be an easy swap if it doesnt line up with the radiator. I will keep an eye out for theat soon as to not delay the build when I get to that portion of it.



I have another question that doesn't really have anything to do with this post, can i buy resistor wire if i wanted to rework my stock harness?

here are a couple of pics to show you what I'm working on now.

['68OrangeSunshine]

Originally Posted by WB72

For sure it is for the TCS thanks for the diagram Jason.


I have another question that doesn't really have anything to do with this post, can i buy resistor wire if i wanted to rework my stock harness?

here are a couple of pics to show you what I'm working on now.

Possibly M&H fabricators could make up one for you. You may already have it in that bundle. It's a Pink 20, that splits into two Yellow 20s, one to Starter and one to Coil. For a lot less you could use a regular wire with a big ceramic Mallory resistor, if you want to keep points. Seen top of pic.
[I sometimes wish it was as easy to tune an HEI, as Points were with a Dwellmeter.] I forgot the p/n: "700, 701, 7000"?... possibly. I used to run it when I had a big square Mallory coil and points. Also tried Pertronix. Worked great for 7 years, then would black out at 3500 RPM completely shutting off the engine while at speed in gear. I went back to points for a year, until I got an HEI.
[M & H:]
www.wiringharness.com