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Still dealing with vibrations and runnability issues...

Oystercopy

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Hey Guys.. been a while. I'm dealing with what I call a "stumble" in my 440.. its been going on forever, but I've been eliminating some other issues related to vibration like replacing the correct, weighted flywheel, new billet Harmonic Balancer/Damper, all new ignition stuff (except for the Distributor). She'll "misfire" and try to stumble/stall and I have no idea why. I'm told that sometimes the pickup coil in the distributor can fail. MSD wires, plugs, cap, rotor, Fuel Pump, coil (stock type) are all new. Just installed an Edelbrock alum intake a while back to replace the cast iron OEM. Also put a Comp Cam kit in it as well.

I'll be as forthcoming as I can with answers, and any help appreciated!
OC
 

Challenger RTA

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Distributor pick up coil I would do any how. A spare pick up cheap and good to have.check Distributor for vacuum working right,advance and wear on shaft.Vacuum hooked in right place do you have vacuum? It's easier to rob a friends and try it around the block. next I would look for a vacuum leak.intake check all basic tune up .plug wires cap rotor.Open hood in the dark when running. see if you have a fire works show. burnt valve. gaskets,lines,cracked intake. Then move to carb.That's another issue.
 
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Flat-Tappet

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agree with challenger RTA to check your spark advance with a timing light, or swap out dizzy with a known good one if you can.

Could it be a fuel delivery problem? I recently solved a stumble on a different motor that would occur when applying larger throttle openings while driving. I first thought that it felt like an ignition problem. So I threw a New rotor, cap and checked the plugs and wires - all were acceptable- no fireworks from wire cross firing seen in the dark.

But when I advanced the throttle slowly while driving, I had no stumble issues. However, Faster stabs of the throttle that would cause the accelerator pump jets to squirt, followed by ~50% throttle or greater would cause a lean stumble.
Increasing the regulated fuel pressure delivered to the carbs from 4 to 6 psi increased the fuel flow rate enough to fix it.
 
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