Help with Ignition??
Thread Starter
Racer
Joined: Dec 2000
Posts: 422
Likes: 0
From: Mesa AZ
Help with Ignition??
I just changed out my distributor to HEI and I now get backfire thru the carburetor at approx 1/2 throttle. I have checked and rechecked the firing order. I have traced it out several times and all is correct. What else could cause this. The timing is right on. It never did this before with the point distributor. Help please! I have installed wire looms so none of the wires are touching each other either. WHAT AM I MISSING?? I'm so frustrated 
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,364
From: At my Bar drinking and wrenching in Lafayette Colorado
What positive source are you using to feed power to the HEI? You cannot use the wire that normally feeds the "+" side of the coil on the points system since this is a resistor wire with reduced voltage.
Thread Starter
Racer
Joined: Dec 2000
Posts: 422
Likes: 0
From: Mesa AZ
Thank Yu Lars!!!
Thank you Lars,
I'm working on my 69 Pickup and it had a firewall mounted resistor in the old ignition when I bought it so I assumed that it was 12v to the block. The truck had a rewound wiring harness and the wire at that terminal was not resistor but I traced it back and it was resistor coming from the firewall plug. I connected the distributor to the same wire as feeds my elect. choke. It runs fine now. Is there any problem tapping into the wire to the choke??
Thank you so much!!!
I'm working on my 69 Pickup and it had a firewall mounted resistor in the old ignition when I bought it so I assumed that it was 12v to the block. The truck had a rewound wiring harness and the wire at that terminal was not resistor but I traced it back and it was resistor coming from the firewall plug. I connected the distributor to the same wire as feeds my elect. choke. It runs fine now. Is there any problem tapping into the wire to the choke??
Thank you so much!!!
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,364
From: At my Bar drinking and wrenching in Lafayette Colorado
Depends on where the electric choke is hooked up - since electric chokes were not offered in '69, somebody has run that wire from someplace. Check the source on the power to verify that it's coming from an "IGN" source and not an "ACC" source (should have no power to the ignition when key is in the accessory position). If it's a true 12-volt source keyed to ignition, you're in good shape.
Thread Starter
Racer
Joined: Dec 2000
Posts: 422
Likes: 0
From: Mesa AZ
Lars, any tips on lowering HC at idle??
Lars,
I'm trying to get this pickup thru emissions and I'm failing HC only at idle. The standard is 450 and I'm running around 465. Do you have some tuning tips to lower HC at idle please. I think I read something you had on here about this a couple of years back but can't find it.
Thanks,
Chad
I'm trying to get this pickup thru emissions and I'm failing HC only at idle. The standard is 450 and I'm running around 465. Do you have some tuning tips to lower HC at idle please. I think I read something you had on here about this a couple of years back but can't find it.
Thanks,
Chad
