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Old 03-17-2005, 01:25 PM   #1
redz 1970 K5
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IGNITION PROB... THE FINAL FRONTIER. help!!

So, when I was pulling the old distributor and wires, I was like baahh, child's play, I can get it back together and didn't pay close attention to the wire routing.

I dropped the new distributor, hooked up the ignition module and the 12v, and ran new plugs and wires.

She cranked, but would not fire. Fuel is definitely getting into the cylinders, so it is definitely ignition. I got the engine set to TDC, made sure the rotor was pointing to cylinder 1, and I confirmed I have around 10 volts to the Distributor. This is how my wires are routed now-



Now, after checking more things, I looked at the old cap. It's routing is like this-



All manuals say the above pic is the norm, but my old routing is different. Since it ran, I am suspecting I need to run the wiring and reset the distributor pointing to 1 at TDC and try again...

Can anyone shed light on this? It's a 74 engine.
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Old 03-17-2005, 01:46 PM   #2
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Sorry, All I have is the manual for the 71Jimmy, not HEI, but shows wiring as in pic 1, first pic. Do you have spark? You probably did this already but unplug spark plug wire from cyl one spark plug, hold wire just above the plug and have someone crank, should see a spark arcing from the wire to the plug. May need to put a bolt into the end of the wire to extend out of the boot and have it somewhat dark in the garage. I ussually hold the wire with a pair of insulated pliers, so I don't get that tingle in my arm when she cranks.
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Old 03-17-2005, 01:47 PM   #3
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Did you changed from points to HEI ? If so the 1st diagram is the one to use. The 2nd one is how a points dist. was wired. You will need to retime your dist. so that rotor is pointing to #1 @ TDC in 1st diagram.
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Old 03-17-2005, 01:56 PM   #4
redz 1970 K5
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I swapped an old OEM HEI dizzy for a new aftermarket HEI dizzy. No kidding, the old HEI was wired as in pic 2. That's why I am confused.

Last night, I set TDC and retimed the dizzy to insure the rotor was pointing to position 1 on the Cap already ( as in pic 1).

Far as checking for spark, couldn't I just use an inductive timing light hooked up to the wire, and see if the strobe flashes when someone cranks it over?
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Old 03-17-2005, 02:31 PM   #5
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Ok, did some more research. Something changed between 1974 and 1975 on HEI plug wire routing- that #1 position did change between those years... I cross referenced this to confirm, and am 99% sure that pic 2 is the correct routing for my truck.

Of course, can't it be said that as long as the firing order is correct, and that plug 1 corresponds to cylinder 1 at TDC that it will run? So plug 1 can be in any location? Or is there something in the ignition that requires a specific routing?

WEIRD...
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Last edited by redz 1970 K5; 03-17-2005 at 02:57 PM.
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Old 03-17-2005, 03:19 PM   #6
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Bring your number 1 cylinder to top dead center and make sure you stab the distributor so that your rotor is pointing there and then start wiring according to which diagram you use. I've never heard of the firing order changing on an HEI distributor. New to me.
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Old 03-17-2005, 03:28 PM   #7
redz 1970 K5
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The firing order didn't change, just the location of the wires... I am sure I can use either pic 1 or 2 , so long as #1 is at TDC.

But, thanks everyone for the help. Any more troubleshooting tips would be appreciated.
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Old 03-17-2005, 03:36 PM   #8
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Well, if you insist on doing it the easy way I suppose hooking your timing light up would work. I however always do things the hardest way humanly possible, gives me an excuse why I didn't finish. LOL
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Old 03-17-2005, 03:44 PM   #9
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HAHA!

She's coming out of the garage tonight or tomorrow morning, either under her own power or mine... I can do the rest of the work in the driveway at this point.
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Old 03-17-2005, 06:56 PM   #10
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I know it's obvious but it hadn't been mentioned.
TDC, yes of course but make sure it's on the [compression stroke]
I'm sure you did but just checking.
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Old 03-17-2005, 07:17 PM   #11
redz 1970 K5
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Yup, I crank the crank cwise while my finger is over the #1 plug hole. As soon as I start to feel a push of air, I just continue to crank the engine over until the mark on the h-balancer lines up with the timing marker at 0 Degrees.
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Old 03-17-2005, 09:18 PM   #12
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how did you wire power up it should not be 10 volts should be 12 did you run a new wire for power? if you connected to old yellow wire that may be problem
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Old 03-17-2005, 11:21 PM   #13
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Not trying to be a smartazz or questioning your ability but you did use the drivers side front cylinder as no. 1 and not the passenger side.
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Old 03-17-2005, 11:24 PM   #14
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I also noticed the 10 volts mentioned. You should be getting a full 12 volts at the distributor for an HEI to work properly.
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Old 03-18-2005, 12:05 AM   #15
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The original ignition wire that runs from the connector on the firewall is some special type of wire that has high resistance to drop the voltage. The yellow wire from the starter motor temporarily raises the voltage to 12 volts while the engine is cranking. I installed an HEI distributor in my truck a while ago. I got rid of the original ignition wire and the yellow wire from the starter motor. I ran a wire from the fuse panel through the firewall to the distributor.

If you hook up a timing light and have an assistant crank the engine over, you can check to make sure your timing is correct.
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Old 03-18-2005, 12:36 AM   #16
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#1 can be anywhere you put it. In all reality, it doesn't matter where it is. Bring the engine to TDC...then back it about 8 degrees. Stab the dist into the hole and make sure you get the oil pump in the grove...if you can clamp it dowm then it's good.
Pop the rotor on there. Where ever the end of the rotor is, is now #1. I usually mark the base of the dist exactly in line with the end of the rotor.
Now clamp the cap onto the dist. Locate the mark on the side of the dist body. If it is directly under a spark plug wire tower, then wire it 1843....ect.
If it is not directly under a wire tower, then rotate the dist untill it is.
Then wire it.
Asuming you have it at TDC on compression, like you indicated, then it'll fire right up as soon as you hit the key.
The 10 volts you are reading...your battery is probably weak. Dome light on, crankin the crap out of it...listing to some tunes...ect. The resistance wire woulda cut it down lower than 10, so if it'll crank, then you'll be OK on that.
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Old 03-18-2005, 04:38 AM   #17
redz 1970 K5
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So, after some more troubleshooting, it ended up being the splice to the HEI ignition; it is spliced into the pink wire from the firewall, it is a 12V switched source. I started at the coil and started tracing back... Voltage was correct on the truck side of the splice, but low on the HEI lead... Just removed the splice, soldered and shrink wrapped the joint, and voila 11.8 volts.

Hooked up the timing light, cranked a few times (it was like 11:30 PM with open headers, so I couldn't start her), but the strobe of my timing light was strobing, and I know my wires are setup right, so all signs point to go tomorrow AM.
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Old 03-18-2005, 09:50 AM   #18
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first off, i just wanna say good luck Redz. obviously, we're all pulling for you. secondly i wanna say that this thread is awsome for information and just plain old troubleshooting ideas. thanks everybody
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Old 03-18-2005, 12:47 PM   #19
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And.............????

I'm sure you're havin' too much fun now with it runnin' and all. TELL US!

You gonna be at DelMar?
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