hei distributor question..

[rodstored-72]

hey all,
i have another question. i am hooking up the factory m&h engine harness now & i have a mallory hei distributor. my question is can someone tell me what the wire is that is the dist. pwr wire on the harness that i need to splice onto the pwr wire on my distributor connector. i am also wanting to dbl. check something. i am understanding that 1 lead is for the pwr to the dist. & the other lead (both leads are on the dist.) is for the tach.? if that is right then i should run the wire for the tach directly to the tach in the cab (aftermarket) & then the tach gets pwr from somewhere in the cab??? i hope this is right, anyways if someone who has done this could give me a idea of how to hook up the hei dist. it would be much appreciated!!!!

thanks again & in advance for any & all help!!!

rodstored-72

[jimmydean]

You should be able to run the hei off any switched 12 volts. The tach should have a seperate lead for power from the one that goes to the dist. It is also switched. Hope that helps, but ther might be a less redneck way to do it

[rodstored-72]

sorry guys i still not follow. so can i take the yellow wire that would normally go to the coil & splice it to the red pwr wire from the dist. wire next to the tach wire????

thanks!!!

[jimmydean]

Not sure as i don't have the same dist. But just use a test light, turn on the truck, poke the wire, then repeat with the truck off. If you have power with the truck on and no power with the truck off, your good to go.

You just need 12v that is on with the truck (i.e. switched 12v vs. constant 12v from the battery).

[pjmoreland]

Originally Posted by rodstored-72

sorry guys i still not follow. so can i take the yellow wire that would normally go to the coil & splice it to the red pwr wire from the dist. wire next to the tach wire????

thanks!!!

Don't use that original yellow wire. It won't provide the correct voltage for the HEI. Here are two suggestions on how to power the distributor:

1) Run a wire from the "IGN UNFUSED" terminal on your fuse panel to the power terminal on the distributor.

2) Do as Shifty suggests in his FAQ submission about installing an HEI in a 6-cylinder engine and run a new wire from the big square black connector on the firewall to the power terminal on the distributor. This new wire replaces the old pink wire that tees into the yellow wires that connect to the coil and starter motor for the original points distributor setup.

I had mine setup the first way originally, and about a week ago I took Shifty's advice and redid it the way he suggests. It looks way cleaner this way because now I don't have this random wire running through my firewall to the distributor.

Here's the link to Shifty's writeup:

http://67-72chevytrucks.com/vboard/s...d.php?t=148346

[pjmoreland]

I also installed the correct OEM HEI connectors on the end of the distributor power wire and the tachometer wire. I purchased them at this place:

http://www.ronfrancis.com/wiringaids.php

I'm not a big fan of crimp-on spade terminals.

[rodstored-72]

thanks,
i pretty much understand (after reading shifty's article with putter's comments). i just find it hard to believe that everyone who wants to change over to hei would have to do that. i just bought the m&h wire harness, i really don't want to tear it apart to replace the white wire which leads to the yellow wire. i know me & if i get into that wire block I will for sure screw it up!. i really dont want to do the single wire by itself thing either. anyways if someone might have some more suggestions i am all ears. i am also going to think about what shifty & putter did, i may go ahead & give it a shot. it's only money right!!

thanks abunch!!!

rodstored-72

[pjmoreland]

If money's no object, you could buy a complete engine harness already made for HEI for $95.

http://www.gmcpauls.com/wiring_harnesses.htm

[glock35ipsc]

Originally Posted by rodstored-72

thanks,
i pretty much understand (after reading shifty's article with putter's comments). i just find it hard to believe that everyone who wants to change over to hei would have to do that. i just bought the m&h wire harness, i really don't want to tear it apart to replace the white wire which leads to the yellow wire. i know me & if i get into that wire block I will for sure screw it up!. i really dont want to do the single wire by itself thing either. anyways if someone might have some more suggestions i am all ears. i am also going to think about what shifty & putter did, i may go ahead & give it a shot. it's only money right!!

thanks abunch!!!

rodstored-72

The original wire in the harness that runs to the coil is a resistance wire. It will not provide enough voltage to let an HEI operate properly. If you want to use anything other than a points distributor, the resistance wire must be replaced or bypassed.

[ChevLoRay]

I ordered a wiring harness for my '69, from M&H Fabricators (www.wiringharness.com), WITH the HEI hookups already done. I don't understand that you got a harness from M&H that caused you a problem with hooking it up. There should have been no question about installing it. Their stuff is great, with matching color codes, factory connectors and so forth.

[glock35ipsc]

OK, maybe I confused myself. You are using an aftermarket harness, correct? Not the factory original? If it is aftermarket, was it designed for a points ignition, or an electronic ignition? Best thing to do is check the voltage of the yellow wire in the harness, the one that used to go to the coil. If it is more than 12v, that should be the one to connect to the power input lead on the distributor. If it is less than 12v, it is either a resistance wire, or it runs through a resistor somewhere. If I remember correctly, the resistance wire would read somewhere around 9v, +/-.

Bottom line, you need key-on 12v to power up the distributor.

[rodstored-72]

Hey guys,
thanks for that great input. i probably didn't explain as good as i could have. sorry... i bought the wiring harness from a local place here called ricks pickup parts (mesa). i know that it is a m&h harness. it is for a 1972 chevy 2wd v8 p/u. my understanding (the reason for the original post) is that the i wanted to know if the yellow wire could be used to hook up to the pwr lead at the mallory hei distributor? i don't know what a factory '72 chevy truck had as far as voltage to the coil & distributor. it would be great if the yellow wire from the m&h harness is set for 12v cuz then i could just splice together. but if the yellow harness wire is less then 12v then i guess i will need to figure out what to do. anyways i am going to call the place that i bought the harness from & ask them as well. i just haven't been able to get by there yet & i wanted to talk to them in person- iwill call them today.

i hope this clears up any confusion i may have caused..

thanks again for the great help!!!

rodstored-72

['68OrangeSunshine]

The yellow wire in the stock wiring harness is linked to the white/purple/orange striped wire coming out of the bulkhead connector and fed from inside the cab by the pink [Ign] wire. Its function is to supply 12 VDC to the starter for ignition, then -- when the single strand iconel line inside the Wht/Ppl/Or heats up to operating temperature it's resistance increases and it drops the voltage to 7.5 ~ 9 VDC so the points and condenser in a stock distributor won't burn up too early. If running HEI you need to bypass the Wht/Ppl/Or with a constant 12 VDC feed from an Ignition On source. Also they run best with a 10- or at least 12- gauge line. I used red 10 gauge. M&H makes good stuff, they will build you a harness for your specific application/modifications when you mail order, but if you buy the wires off the shelf, you miss out. To keep the stock look, you can wrap the "red" 10 Ga line into the bundle with black no-stick vinyl tape [Eastwood has it] and only you will know it's different inside. Also, a voltage check on a cold engine will read 12 VDC on the
Yellow and/or Wht/Ppl/Or line.

[70rs/ss]

Ask Rick to exchange your harness for an hei harness, providing you haven't cut it up, he'll swap you harnesses. Rick is a great guy to work with. I am headed there to buy a ton of parts this weekend. I'll be in the valley for the Nascar races, and I'll stop in a spend the $$$!! He is good to work with, and if you guys are looking for another source for great parts at even better prices, check him out. He does shows (swapmeets) etc and gives even better prices as well as no tax, and or shipping!!

[rodstored-72]

70rs/ss
when do you think you will be there (ricks)? i will try to meet up with you there & switch harnesses. i have not done any thing to it except run the wires to where they go. everything is new so all is clean. i will meet up with ya there. atleast we can meet in person. anyways i will give your idea a shot. if not then i will run a new wire next to the harness wires & connect at the bulkhead.

thanks again for all the great replies. you guys are really smart!!!

rodstored-72