If you want a carb built correctly. Send to Dick Paterson ONLY. Or use that money better. And install a Howell/GM EFI system with spark control. Jim K at Applied GMC has the kit. Simple to install. These fuels that are out there now. Are formulated for EFI systems. Thus don't, and NEVER will work well in a carb. Bob Dunahugh 78 Royale Iowa