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FE Technical Forum / Re: Who's running 2x4 Holley BC/BD Carbs?
« on: October 31, 2015, 01:14:00 PM »
I have no reason to change metering blocks as the orig. Holleys work fine. IMHO there is no need to look for a problem that doesn't exist. But with that said I have found that late model Holley metering blocks can have problems in the emulsion part of the main circuit but early, say 60s thru mid 80s seem to work fine as they have a more precise fuel curve and respond accordingly. I have cured some idle/main transition problems by using a early metering block and matching the IFR and PVCR sizes to the orig. carb's metering block. Seemed the problems with the fuel curve was more associated with Street Avenger type late style carbs. If I needed a metering block I don't already have or anything that had anything to do with precise fuel control Quick Fuel would be my 1st choice. As far as the BC/BD carbs being too rich that can be something as simple as a warped main body's met. block surface and the gasket is not compressing evenly allowing cross channeling or leaking into the power valve vacuum chamber. I have also found OEM carbs have more precision circuitry than over the counter replacement type carbs as these carbs are subject to emission control and testing, they have to be correct. For example a 780 cfm 3310-1 4150 is the correct OEM carb for a 375 hp/396 Chevy whereas a 3310-2 thru 10 is a over the counter replacement 750 cfm straight leg booster 4160 [no sec. metering block] The 3310-1 is a excellent carb to work with, the others? not so much. I cringe any time some one says they are dumping their OEM BC/BD or BJ/BK carbs for a cheap pair of 1850s from Summit or Jegs just because they can't get the orig. carbs right. If yer gonna toss the old ones...toss 'em my way, I'll be happy to take them off your hands at no charge to you