HEI Problems

[1-PU70]

I ran the power to my HEI through a relay and when I shut it off it takes a few seconds till it actually does. Turn key off then wait a couple of seconds then it turns off. I have done this on several trucks with the same results. Is there a special relay where this wont happen. Do I need one with a diod in it? I used the wire that was powering the HEI to switch the relay. So its defiantly the relay.

[lowriden58]

I dont believe there is any need for a relay. just a fused lead wire from your battery or other 12v source. im not running any relay on my HEI

[MickMc]

Call Mark from Mad Electrical. He will know the answer.
http://madelectrical.com/
I just wired a relay for my HEI too, but the truck is not ready to fire up yet and need an answer for the same problem.


And yes you should always run a relay to turn on and off anything!


Mick

[Olden Days]

I used a relay on my HEI also because it is part of a little theft deterrent device I made but I have no issues with it continuing to run. Hit the key and it kills immediately. It is a regular Bosch style relay.

[1-PU70]

Its a 4 prong relay. Power in 30, power out 87, ground 85 and switching power 86. Im using 10ga wire for power in and out and 14ga for ground. Not sure about the switching wire it was there, looks like 16ga

[Olden Days]

Looks like you have the bosch style relay. I am clueless, That is the way mine is wired and it works like supposed to. except I also have the 87a post which makes it a dpdt. I use the 87a as an indicater light but tht wouldnt make a diff to your situation.

[1-PU70]

I was just looking at some other ways to wire it and some use the switch on the ground wire?????

[Olden Days]

this uses both ground and ign. for switching. Are you familiar with a reed switch? You would hide it somewhere and use a magnet to activate
That is kind of a weird relay there and one could wire 2 regular bosch together to acomplish the same thing but you would end up using 3 relays for the whole thing.

[dznucks]

you mentioned that you used the wire that powered the hei to switch the relay. this wire is supplying full battery power to trip the switch.

the relay is designed to be tripped with a low power/current signal and in turn it closes a larger power circuit. i jumped off a smaller wire from the ignition or fuse block, that is turned on by the key, to trip my ignition relay.

i suspect what is happening is there is too much power tripping the relay and when you turn the truck off the larger power signal is taking longer to die down below the power signal threshold that trips the relay. this is causing the relay in when the motor turns off. you might need a larger relay or find a new supply wire.

[VetteVet]

Originally Posted by lowriden58

I dont believe there is any need for a relay. just a fused lead wire from your battery or other 12v source. im not running any relay on my HEI

You are correct except that it needs to be a key switched source otherwise it will drain the battery. The most common source is the ignition unfused terminal in the fusebox. Some guys use a fuse for the HEI and some don't.
I would use the relays for the headlights to provide more voltage to the lights and less power run through the light and dimmer switches.
For the theft deterant guys, As for using relays and fancy circuits to avoid theft, it's a waste of time. Any thief with a knowledge of these trucks would be gone with the truck in less than a minute. I could have the truck running before you could get the keys in the ignition and I'm not a thief.

[Olden Days]

Originally Posted by VetteVet

You are correct except that it needs to be a key switched source otherwise it will drain the battery. The most common source is the ignition unfused terminal in the fusebox. Some guys use a fuse for the HEI and some don't.
I would use the relays for the headlights to provide more voltage to the lights and less power run through the light and dimmer switches.
As for using relays and fancy circuits to avoid theft, it's a waste of time. Any thief with a knowledge of these trucks would be gone with the truck in less than a minute. I could have the truck running before you could get the keys in the ignition.

I guess you dont lock your house either then because someone could break a window or pick the lock.
Granted nothing is fool proof but they are deterents. And if you wernt so far away I would make a private (friendly)challenge that you wouldnt be driving off with my truck. I dont post things exactly the way I did them.

[1-PU70]

DZNUCKS you have given me something to think about. I wonder if I use a ballast resistor in my switching line it might do the trick.

[VetteVet]

I guess you dont lock your house either then because someone could break a window or pick the lock.
Granted nothing is fool proof but they are deterents. And if you wernt so far away I would make a private (friendly)challenge that you wouldnt be driving off with my truck. I dont post things exactly the way I did them.

Please don't take offense at my reply, I know that no one would be foolish enough to tell their secrets to the world, however their are many people that think a hidden switch or some way to kill power to the distributor or the starter is going to stop a thief. Yes I do lock my house, but it only keeps the honest people honest. There are much better ways to avoid theft than disabling the distributor which is what my reply was directed to. I'm sure you know this and yes you probably have one installed. I figured someone would issue me a challenge because it was a bold statement to make.LOL

[1-PU70]

Its not meant to keep someone from steeling my ride. I just about always keep the key in the ignition. My luck I would loose the key. I just know how important it is to have an HEI with full current and I tend to take things to the extreme.

[LONGHAIR]

you mentioned that you used the wire that powered the hei to switch the relay. this wire is supplying full battery power to trip the switch.

the relay is designed to be tripped with a low power/current signal and in turn it closes a larger power circuit. i jumped off a smaller wire from the ignition or fuse block, that is turned on by the key, to trip my ignition relay.

i suspect what is happening is there is too much power tripping the relay and when you turn the truck off the larger power signal is taking longer to die down below the power signal threshold that trips the relay. this is causing the relay in when the motor turns off. you might need a larger relay or find a new supply wire.

I see several problems with this theory.
It is a 12volt system, and the relay gets that same 12v to activate the relay.
There is no "low power" signal. The point of the relay is to reduce the draw of large devices from the switch. The relay is designed to carry this load.
Too much power tripping the relay? Taking too long to "die down"?
It's 12v D/C...instant on/off. Unless there is some capacitor somewhere to store power, this can't happen.

You need to test the wire(switching) itself first. If it is not going off when you think it is, the relay won't either. A simple test light can confirm this.
If the power to the relay does go off, the relay should too....if it doesn't the relay itself is faulty. If the terminals would stick, for whatever reason, or the spring unable to overcome it....the relay could stay closed. Test light here too.

My thought, bad relay.....or the switch itself is not going off when you think it is.

[neonlarry]

My guess is that the wire supplying power to the relay coil is getting some feed back from the alt. I have that problem with my remote starter solenoid and had to put in a seperate relay to solve the problem. Easy way to tell is if this wire is easily unplugable, in stead of turning off the switch just unplug the wire and see if it shuts off immediately.

[MickMc]

Originally Posted by VetteVet

Please don't take offense at my reply, I know that no one would be foolish enough to tell their secrets to the world, however their are many people that think a hidden switch or some way to kill power to the distributor or the starter is going to stop a thief. Yes I do lock my house, but it only keeps the honest people honest. There are much better ways to avoid theft than disabling the distributor which is what my reply was directed to. I'm sure you know this and yes you probably have one installed. I figured someone would issue me a challenge because it was a bold statement to make.LOL

Do share some other theft deterents.
I'm all ears.

Mick

[1-PU70]

Well I got out my multi meter and did some checking. There was some residual current in the switch wire. Not enough to light my test light but some none the lees. I now have a different wire with no residual current for the switch wire. Ill let you know if it makes any difference after I drive it today.

[1-PU70]

The multi meter is my friend. After driving with several on off cycles it turns right off now. It was only getting .03 to .05 volts. Now it gets O. Thanks for everyone's help

[Never Satisfied]

I used a relay to power my hei. i picked up the pink wire from the ignition switch--this wire is a resistance wire .you will have to cut it back to about 4"from the wire connector [ on firewall] or replace it completely' to provide 12volts for the relay coil.

[Longhorn Man]

the pink wire on the back of the switch isn't a resistor wire.
Another common reason for this kind of run on is electric fans wired on the same circuit

[airdale94]

On a starter interupt you need to run a diode between 86 and 85. Don't know if this applies to your setup.

http://www.bfranker.badz28.com/fbody/starterkill.htm

[my70chevyc10]

I just ran a new wire from the fuse block from a turmenal that was only on with the key if you run the wire stright from the battery the truck will never shut off untill you disconect from the bottem of the HEI cap.

[cparman]

I went to dinner in my 69 tonight. The HEI is wired hot with the key on. No relay. I had not heard of this until I started reading the board. My wife and I drove my 69 to Ragtime, and parked in between 2 other cars EEEK! left it unlocked. Someone could have stolen my copy of Michael McDonald's motown CD EEEK!! Starts and runs just fine!!
I love my old truck. 700r4 comming in the next week or two. I am SURE I will love it more