Reply to "High Speed miss"

John, questions like this are difficult enough when you're standing next to the thing.... OK, first check if your Holley is equipped with an electric choke. Trace the hot wire from the choke and be sure some "mechanic" didn't attach it to the 12v coil wire. This will absolutely limit rpms to 4500-5000 due to lack of volts to the coil. If the choke's wired correctly or not present, it might be some 30-yr-old valve springs floating or broken. Pulling the valve covers will let this be checked. Third, are the secondary throttles actually opening? Even experienced engine guys occasionally get vacuum-secondary throttles stuck closed or the actuating diaphragm torn, leaving you with a fairly small two-barrel carb. Finally, 351Cs are very hard on cam chains. They get sloppy after only 25K miles, and when that happens, they retard under load and advance during shutdown. Try all these in order of difficulty/expense and let us know what happens.