"I put the lightest springs in the vacuum advance tonight and I will see if it makes any difference tomorrow."
Do you set the timing with the vacuum advance hooked up? Try disconnecting it completely. The vacuum advance is different than the mechanical advance, although they both advance the timing.
Read the info that came with the distributor. It may tell you how much mechanical advance it comes with, how to adjust it and whether or not it is easy to adjust without having to weld and file the slots.
Check for vacuum leaks. Check your float levels, power valve sizing and function, accelerator discharge nozzel size, jet sizes and idle A/F settings.
Are you running a PCV valve on this motor?
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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