The idol mixture screws screwed all the way in, make the car race. With both screws screwed all the way in, it should of course die... Right? I decided since it backfired and there is NO PV protection, I purchased the Holley #125-500 kit and installed them both today. Put it in and it still does it. I installed the new 4.5 PV's at the same time. The tech guy I called at Holley tech line said it has to be getting fuel some other way thru the metering block, and that he doesn't know what to do, and to send it back. I still can't diagnose any other problems now. I'm Fu*#ing pissed! .. D