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Hey its me again.
I am going after this pesky off idle shudder I have with my 67 Coronet 500. Its a stock 383 with the 1405 EDDY. MP distributior with pink springs.
From day 1 that Ive owened this car there has been this off idle shudder.
Choppy idle, Cool sounding, Just off idle it shudders untill you get to about 950 rpm. It smooths out and all is good.
Cap, rotor, wires, carb kit, ( I know how to use a vacuum gauge ) Its tuned to the best of my ability!
I degreed the balancer, Im at 38 deg all in at 2600.
I dont use vac advance. I hooked it up to see if it would cure? Nope.....
Im leaning twards the distribuitor as being the issue. Sticky breaker plate?
Carb? Im at 3 turns now on mixture screws. Have not messed with the re jetting thing yet either.
What direction should I go? Distributor or Carb?
Thank gang!
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Most of the time it's from the vacuum advance coming on too quick, but I see you prevented that from the get go.
Why did you disconnect the vacuum advance anyway?
President, New England chapter of Coronetaholics anonomous.
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Engine off.... Look down the carb. and roll the throttle back and check the accelerator pump spray. The accelerator pump could be lazy or out of adjustment which would cause it to come in late and give it a stumble. Just a thought.
Good luck, Danny
If your friend Jack helped you off a horse....... Would you help your friend Jack off a horse?
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I disconnected the vacuum advance due to part throttle ping at road speed. 55 mph, no load flat road.
Never adjusted the can to stop that ping.
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It's not at stumble. I can hold the throttle at 750 rpm just off idle and it will shudder and not stop till I get over 900 rpm.
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05-07-14, 09:41 AM
(This post was last modified: 05-07-14, 02:03 PM by 65rbdodge.)
I think I have heard that eddy carbs are known for this off idle stumble. although I own one, I have never used one so I cant say for sure. for some reason I remember in a seminar with herb mccandles something about a check valve being the problem. he said to remove the ball and it would be ok. google it and see what you find. sorry I`m so vague, the memory is the first thing to go.
EDIT: GOOGLE THIS- edelbrock off idle stumble
I didn't even have to finish typing it and it was "autocompleted" it seems to be a common problem
Nobody wants a Charlie in the box
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Okay, so back up a bit... is the compression even in all cylinders? (max of 10% difference). (The backyard way to check is to set the idle to the point that it shudders <750 RPM> and pull each spark plug wire while the engine is running to see if they all have an equal effect on the idle, if one doesn't... that's the problem cylinder). That would be a good reference point. If one cylinder is down slightly, it will only show itself at low RPM.
If the compression is even, check to be sure that the mixture screws are properly set to balance the engine. Just remember that they may not be the same number of turns for each side.
Just my 2 cents.
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Thanks Ftatzog. My compression tester got loaned to a buddy who never gave it back.
I am going to hook up my timing light and see if I get any movement at the mark going thru that shudder.
Then do the wire pulling test.
If time? Ill pull the distributor and inspect the advance mech for sticking...
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Gonna bring home the FLIR camera tonight. (Infrared)
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Update:
FLIR camera shows a cold cylinder. Passenger side #2 from the front.
Timing light shows no movement of the mark at idle through the shudder. Just as you pass through the shudder the mark jumps.
So? Would a worn distributor cause this? Also the miss doesn't help either.
Gonna can the Taiwan dist cap and rotor and get mother mopar ign parts.
Thoughts?
