holley 750 marine carb model 4010
 

(# R84018 Date code 2048 ) Is a this junk carb?? Does not look like a standard holley. We rebuild mine and still have problems. It pops and backfires in the mid-range. Vacum at idle is only 10-15 psi. Is vacum a problem? Is the power valve the problem?? I may have a large cam not sure what size. I have a quad jet carb will that work better??