Sorry to resurrect this thread, but I still need help with this.

I have seen HEI conversions wired into the fuse panel with nothing more than a spade connector. I've also purchased cars that were running on the stock resistor wire. What is the best way to add a wire for an HEI conversion? TIA!

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See you at Chevell-abration!

[This message has been edited by Alan F (edited 05-23-99).]

NOT the resistor wire. HEI needs 12volts.. spade connector the fuse box is fine, thats how mine is hooked up http://www.chevelles.com/forum/smile.gif

mike reeh

I have a hei hooked up to the stock ignition wire. it seems t orun ok
how do I know if its hooked up to a resistor wire?

I have tried this a couple ways. When going direct to the fuse block it works well if your fuse block is in good shape. If the block has loose joints or corrosion it can give you running problems. I have also tried using a Bosch style relay triggered by the resistor wire and taking power from the stud on the horn relay. This is my favorite as it puts full 12v to the HEI with a fairly direct path. Also, this is the method suggested by Jacobs in his ignition book.
I had purchased one car with the HEI hooked to the resistor wire and it ran poorly when the throttle was opened; adding the relay fixed it.

The car will run if you use the resistor wire but you are only getting about 8 to 9 volts and the HEI wants 12. The vehicle will run much better with a full 12 volts.

I also went directly to the fuze box ignition stud with a 13 gauge wire but I have heard of the horn relay idea, either should work - use a volt meter to insure you have a clean 12 volts of "switched" power.

John

JWagner,
That's the method I was looking for. Can you tell me anything more about the Bosch relay - part no. or application?

I switched the fusebox spade in my 73. I yanked the skinny resistor wire and used a 14 gauge connector I got out of a HEI equiped Malibu (76?) this worked beacuse the firewall fusebox half was identical to the '73, the spades may not intercange with older models.

The relay idea sounds cute, but perhaps use a fuel pump relay which is designed for continuous use instead of a horn relay.

73: the type of relay I had in mind is quite similar to the fuel pump relay and looks identical. It just does not have all the extra Bosch circuitry inside like a fuel pump relay. Capacity can be 30 amps for the small ones.

Alan F - you can pick up the bosch relay at just about nearly any parts store. Just look in the electrical section, it should be about an inch cubed (or a cubic inch, i guess!) with a mounting tab and 3 or 4 terminals on the bottom. They are usually made of black plastic. It should cost between $5 and $8. I think that the relay method is the best way to run an HEI system, because you don't have to hack up the stock wiring harnesses or try and run a wire through the firewall.

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Ian McDermott
1970 Chevelle SS 396
Columbia University
New York, NY.
E-mail: havoc@graffiti.net
Web page: chevelle.dhs.org (http://chevelle.dhs.org)
ICQ UIN: 3923441

So I ordered and received my relay, with plug, from J.C. Whitney. It has 5 wires - 3 wires (red, white and yellow) are 12 guage; the other 2 (green and black) are 16 guage. I can deduce that one of the smaller wires should be hooked to the existing ignition wires, the other to, possibly, ground? One of the 12 guage wires should go to the coil on the HEI and another to the 12V power source (I'm going to use the horn relay mounted above the brake booster). That leaves one extra 12 guage wire.

The cryptic diagram on top of the relay doesn't compute with this accountant. It appears that one of the 12 guage leads would be "on" when the relay is open? Which wire is which?

I have three ohmeters that have either dead batteries or are broken - AARGH!

Without looking at the diagram I can only offer a guess. you are correct about the two smaller wires. One goes to ignition switch, the other to ground. ( it should not matter which way). The Larger terminals are probably wired so that 1 is an input from a power source. 2 is hot with circuit de-energized. 3 is hot with circut energized. without the multimeter you can verify the circuits with some wire and a small light bulb.

Clark

If you use the fuse box terminals to wire your HEI "Hot" wire, does it have to go to the switched terminal or will it hurt to keep power on it all the time from the unswitched terminal?

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Long time Chevelle fan and an owner since 1973 :)

Ok, here is the wiring scheme that works for me. Assuming we are still with the ever popular JCW kit, try this: Lose the yellow wire that goes to the center terminal (87a) as this is not used. The small gage black wire will get hooked to your original coil resistance wire to apply a signal to #85 on the relay. The small green wire is a ground for #86 terminal; this will get grounded to the bodywork of the car. The power from the battery (or horn relay stud) connects to the fat red wire for terminal #30. The last wire is from terminal #87; this is the fat white wire that will go to your HEI. Hope that this clears it up a bit.

Thank you JWagner. That's exactly what I needed.

Alan
You will be happy to know that the July issue of Chevy High Performance (got mine 5-14-99) has an article on this subject. Only thing is they are running fans.
The aticle has pictures and explainations too-might help. BTW JWagner is correct in his explaination too.

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Rick Schaefer
72 El Camino
ACES # 00140

Last question/issue:

I wired it all up per the above instructions. Bought another multi-meter. Tested the lead to the coil without plugging it in. Had full 12v in the on and start positions. Plugged it in. Started it up - Hooray! Turned it off - the car kept running. I had to remove the lead to the coil to kill the car. After I removed the lead, the circuit had no voltage in the off position. What did I do wrong?

Recap of wiring:
1. Factory ignition lead (w/starter relay backfeed attached) to black wire (86).
2. Red 12 guage wire (30) to horn relay.
3. White 12 guage (87) wire to HEI coil "Batt".
4. Green wire (85) to ground.
5. Pulled Yellow 12 guage wire (87a)out of harness.

When I get it working, it makes for a very sanitary installation. I think the detail here is worthy of anyone contemplating such an upgrade. Thanks again to all who have helped.

PS. The reason I couldn't figure out the wiring was because the harness was on the relay. After I took the harness off, I found where the terminals were marked. To quote Homer Simpson, "D-OH!".

You may have a sticky relay. This is unusual but not impossible. To identify this, start your car, turn off the key and if it is still running, tap the relay with a light object such as a screwdriver handle. If it shuts off the engine, then you have identified the culprit. I have had one of these that caused the engine to run on a few seconds after the key was off, but it was temporary situation that cured itself.

I'm sorry to resurrect this thread, but...
I have been tapping the relay to get the engine to shut off. Since I bought an extra relay, I changed it out. The car would not start. http://www.chevelles.com/forum/frown.gif I put the other realy back in and now I can't kill it by tapping the relay. I think it's a really sanitary installation, but I'm getting really frustrated by this. I was thinking of maybe hooking up the yellow wire to ground, so that when the ignition is turned off, it forces it to ground. Any further help would be appreciated.

This seems a little weird that you got 2 defective relays in succession. I guess it could happen. As for the yellow (87a) terminal going to ground, it would not help if the relay is not behaving properly. Have you checked the voltage on the old resistance wire? Is it possible that this is not fully shutting off when the key is turned off? It sounds like you have done the wiring properly, so finding a good relay must be the next step. Third time's the charm?

Alan, I have done a couple of Chevelles by just replacing the resistive wire in the harness from the bulk head connector to the coil with a regular stranded # 14 wire. It's a fairly simple job to do and both cars seem to run just fine on the street.

I don't know about the relay you got but I tried to draw a simple (crude) relay (see link) I don't know if it will be of any help but take a look.
http://macc.chevelles.net/relay.htm

C'ya at Chevelle~abration-99

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Dean Call
A.C.E.S. # 00235
N.C.O.A. # 4350

macc.chevelles.net (http://macc.chevelles.net)

Thanks guys! What I had in mind was to take the power in and switch it from terminal #30 to #87. Take #87a to ground and "Bat" on the coil to #30. This way when it's supposed to be off, the ignition goes to ground. Any problem with this?

I think what I'll try next is substituting a hot lead from the battery instead of the ignition's resistive wire to eliminate that as the source of the problem.

I'll also try to get another couple of relays locally (ha, ha) to eliminate the relay as a source of the problem.

BTW, the brand of the relay is Hamsar(?), obtained from JC Whitney (p/n 42-032; 12 volt, 40 amp). Maybe I can find a Bosch replacement.