Singer66

I have recently rebuilt my 289 motor. Bored it .030 with Keith Black pistons, performance cam, new timing chain and reworked the closed chamber heads. Running it with a Holley 600 with automatic choke. It has pretty good acceleration but when I get to a cruising speed it start to hesitate. Anyone have any ideas what I've missed?

88 orangepeel notch

Your gonna have to be a little more discriptive. Can you tell if your losing spark or gas?

Is it spitting and sputtering, like losing spark on one cyl?

Or just a gradual, slow lose of power when applying gas to maintain a speed?