If you are wired according to that diagram, and have a PROPER relay, you don't need a diode. Looks like you have either the wrong relay or a bad one, a diode is no cure for that!
Also, with the DUI distributor you are better off to run a separate relay strictly for the dizzy. That thing can eat alot of juice.
Huh?...
First...
The relay he's running IS FOR THE HEI.
Second,
The activation wire for the relay is the old Coil/Module wire, and that wire also feeds the 'Excite' wire to the alternator.
When the alternator starts charging, that wire goes POSITIVE and powers up the relay reguardless if the key switch is on or off.
Third,
The Diode is a ONE WAY ELECTRICAL 'VALVE',
It will let the current from the ignition switch 'Excite' the alternator,
But it won't let the current from the alternator backfeed and power up the relay...
Fourth,
The dedicated relay is EXACTLY what the OP needs, and his diagram is correct.
Fifth,
We've done this HUNDREDS OF TIMES for people in the shop,
And I don't know how many people on the forums!...
And it's ALWAYS worked just fine for all them.
I don't know why you think it won't work for this guy?
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To the OP,
The diode, stripe facing the alternator, will solve your 'Issues' (no longer a problem now!)...
We've done this before, and diodes come in the aftermarket ignition kits for this very issue...
If you get your own from Radio Shack, it will be $1.50,
If you get it from the aftermarket places, it will be around $15 plus shipping.
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You are the master! I pulled the wire you said and sure enough the jeep cuts right off with the switch! Thanks for the quick response Jeephammer...it's been driving me nuts.
No problem man, I've been doing this quite a while, and some 'Issues' keep coming around time and time again, and this is one of them...
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I got the relay at Advanced Auto parts.
It's good for what you are doing, since the HEI will draw about 5 amps, and those cheap relays are rated at 30 amps, but are only good for 15 or 20 amps.
This application is about tailor made for the relay you are running.
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How do you guys know this stuff?
40+ years of experience.
Lots of breaking parts I couldn't afford to replace, so I leaned how things worked so I could fix them at home...
Then it turned into a full time job and fairly lucrative business for many years.
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One more question.
I went to radio shack and got a diode.
They didn't have the 276-1443 or -1444 but the did have 276-1143 and -1144 so I got a pack of the -1144's. 3 amps- 400PIV ? sound right?
Yup, I screwed up the numbers, and either of the ones you listed will work with MUCH room to spare.
You are looking at about 1 amp maximum, and about 14 volts max.
PIV means PEAK INVERSE VOLTAGE, and at 400 you are NEVER going to burn or overheat that diode.
Rectifier Diodes are MUCH TOUGHER than the little bridging diodes or other type of diodes, so I use them.
They just last even when I abuse them! (good thing in a Jeep!)
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Maybe the numbers were off a little....just sound too close to be wrong.
Yup, I screwed the pooch... Something that happens daily! I get used to it, but other people still make a big deal about it when it happens...
I always challenge them to keep this many part numbers from 11 dozen suppliers right in their heads and that usually stops the argument/razzing!
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No problem, glad I could help you get up and running again!