I'm looking for some ideas to help out a friend. He has a 1981 Buick Regal with a Chevy 350 in it. The engine is freshly built, with a mid-level cam and a Holley 680 double pumper with a manual fuel pump. The car is otherwise stock.
He describes his issue as a shudder when he takes off from a stop, or when punching it from a roll. Once the vehicle gets above 2000 RPM's or so, it smooths out and runs fine. He describes a slight hesitation when snapping the throttle from an idle. He also feels that the car is slow and gutless and should be much stronger than it is given the performance expectations of the engine.
With some over-the-phone troulbeshooting we determined that the timing is at 6-8 degrees, and carburetor adjustments have no effect on the performance. He says he has taken it to several different places, and everyone tells him something different. One says too much carburetor, another says not enough carburetor, a third says a stall converter will cure the problem.
He tells me that pulling the hose off the vacuum advance does not change the idle. He also tells me that his brake pedal gets hard after two pushes.
I am not an expert on modified engines, so does anyone have any thoughts? Could this be a vacuum issue caused by the cam? Is it indeed the wrong carburetor for this application? My experience with a stock torque converter with a big cam revealed a falloff at takeoff, but not a shudder. Any thoughts I can relay to him are appreciated.
He describes his issue as a shudder when he takes off from a stop, or when punching it from a roll. Once the vehicle gets above 2000 RPM's or so, it smooths out and runs fine. He describes a slight hesitation when snapping the throttle from an idle. He also feels that the car is slow and gutless and should be much stronger than it is given the performance expectations of the engine.
With some over-the-phone troulbeshooting we determined that the timing is at 6-8 degrees, and carburetor adjustments have no effect on the performance. He says he has taken it to several different places, and everyone tells him something different. One says too much carburetor, another says not enough carburetor, a third says a stall converter will cure the problem.
He tells me that pulling the hose off the vacuum advance does not change the idle. He also tells me that his brake pedal gets hard after two pushes.
I am not an expert on modified engines, so does anyone have any thoughts? Could this be a vacuum issue caused by the cam? Is it indeed the wrong carburetor for this application? My experience with a stock torque converter with a big cam revealed a falloff at takeoff, but not a shudder. Any thoughts I can relay to him are appreciated.
