427 down on power

[Chaplin]

Paul-
Check your carb tuning, I bet that your jetting is way off. But first, start with making sure the carb has the correct powervalve in it and then go from there. I would bet that the carb has the stock 6.5 powervalve in it, which probably is not right. The powervalve should be 2 numbers below your measured vacuum reading at idle. For example, if your vacuum was 8.5"/hg at idle, you would use a 6.5 powervalve. However, I would bet that your engine has less than 8.5" of vacuum at idle, which means that if your car has the stock 6.5 powervalve in it, the powervalve is dumping fuel from idle all the way on up, which would explain some of your sooty plugs and may also be why it doesn't want to rev when you get to the higher rpm, i.e., the engine was already supplying max fuel via the powervalve from idle and has no more to give when you get in the upper rpm range. I would also consider getting rid of the vacuum secondary carb and putting on a carb with mechanical secondaries. I used to be a big proponent of vacuum secondary carbs, but when I changed to mechanical secondaries on the cobra it was like night and day.

After you make sure you have the right pv in the carb, see if you can get your hands on an exhaust gas analyzer or a chassis dyno and measure the air/fuel ratios.