Mopar Action On-line – Tech Questions
Ed Butenschoen, Eau Claire, WI, 1965 Plymouth Sport Fury 383-4
Rick, I use your tech info all the time and most of itprinted out for my shop files. Here’s my latest dilemma…
I have a stock 383-4 in my C body with auto trans. A few years ago I upgraded the points distributor with the Mopar Performance electronic unit. I used yourdirections for timing and total advance and the car runs great except forone thing. It surges at idle. I thought the vacuum advance was causing itbut it does it with the advance blocked off too. I rebuilt the carb,replaced the distributor, retimed and adjusted the vacuum advance all to noavail.
I notice a change of around 200 rpm during these surges and a voltagechange at the coil from around 9V to as low as 7V on the + side and avariance of 2-3volts on the neg side of the coil. My question is, Do youthink my problem is voltage related? and if so, What could be causing it?Thanks much in advance to any insight you may be able to provide.
If the alternator is an old 35-45A unit, or has some bad diodes, and esp. ifthe regulator is still electromechanical, this voltage variation may benormal, esp. if idle speed is quite low. Have you upgraded to the 1970-upalternator / regulator systems? Let me know if not, I have some extra VRconnectors lying around.
The other thing to check is that the timing is not varying at idle – thesprings must be strong enough to keep the cam plate at full retard until atleast 100-200 RPM above idle.
I think it is entirely possible that your problem is caused by both systemshortfalls.