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Misses under load

moparcanuck

Deceased, But not forgotton
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My 69 440 Six Pack was running great then all of a sudden, it started missing under load. Idle and revving in neutral is fine. As soon as I put it in Drive, it starts to miss. I checked the wires and did a vacuum test. Everything fine there. Suggestions?
 
Recheck the wires at night. Have someone drop it in gear (put a load on the motor) while you're watching all the plug wires for any arcing. Sounds like a plug wire, plug or distributor cap issue.
 
Take a long screwdriver, put the tip to the block (ground). I had a similar issue once, and went from wire to wire, sure enuff I got an arch from the bad wire to the screwdriver..
 
Stock ignition or electronic?
 
electronic , cant see that making to much a diff if your close to the wire
 
There will be no difference IF ITS A WIRE but it may not be the wire......it may be in the points if its a standard point type distributor.
 
Next I'd wire up a tach (dwell /tach diagnostic tool works) and put it in gear with load. Pull one plug wire at a time (use insulated pliers unless you're a little weird) and watch the tach. As you pull a wire the rpm should drop if the cylinder has been contributing. When you hit the cylinder that is giving you problems, the rpm won't change. You can then narrow it down to that distributor cap terminal, the plug wire/connections or the plug. You can also use an ohmeter on the wires. If memory serves me correctly, resistor wires should have about 5,000 ohms resistance per foot. Keep us in the loop.
 
I recently had a very similar issue with my Bee. Two years ago I added an MSD. In order to add it I needed to convert my dual point to electronic. In order to do that I needed to ad a lead wire to the distributor. The wire that I added developed a crack or somthing. Only noticed while it was idleing and I was moving wires around. Cost me $1 to fix it. Drove me nuts!
KID
 
I have an MSD ignition and will check the wire that goes to the distributor. When I took the plugs out, the rear 4 plugs were beautiful. The front four were black. Not sure what this means. Is the front carb too rich? :eusa_think:

And... the problem disappeared... no more miss. :icon_rolleyes:
 
I had the same problem. Pulled the distrib. Changed over to electronic.
Put in new electronic unit- missed under load.
Found out as I pulled up old distrib. gear drive had turned 1 tooth. Had used vacc. advance to get 5 before TDC-missed.
Brought timing up to TDC aligned slot in Distrib. drive with # 1 tower. Set timing- no problemo.

Good Luck
 
Don't question it...sometimes the stars just align right for you...accept it and move on...lol
 
I put the misses under a pretty good load once and she didn't like it much! :D

Was going to mention it could be a carb problem. Been there a lots. Many times when you get a misfire under load, that generally points to a fuel system problem. Chased my tail with one car and finally threw on a fuel pressure gauge and found there wasn't much....
 
"I put the misses under a pretty good load once and she didn't like it much!"

I needed that! lol...
 
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