484 purple cam..JUNK

It's the power valve.
The carb is your whole problem.
Run 71/81 jets with the rear power valve blocked off.
timing at 38 total.......unhook your vacuum advance.

If you have to turn the idle screws out more then a turn and a half then the idle circuit is to lean------a common problem with a cheap carb.


If i put my 750 holley hp on that 340, your plugs would look like they where run in a fuel in injection engine they burn so clean.

That cam is a great cam by the way.

There is a trend --- as of the last 10 years or so --of over estimating a cams ability to make more power then the next grind.

When your in the right ball park as far as your cam choice -- not to big or small moving to a bigger or smaller cam isn't really the problem solver you would think it is.
--the rest of the car is what makes your car faster then the next guy.