ckessel
Well-Known Member
The general rule is to see if it will hold vacuum. But I've seen them hold after a cough back through the carb and it won't run right until you replace the valve. It would be a good idea for you to stock up on some miscellaneous pieces for your carbs like bowl gaskets, metering block gaskets, metering plate gaskets, idle screw gaskets, bowl screw gaskets, throttle plate gaskets, power valves, needle and seats, needle and seat gaskets. Make sure they are Holley or one of the better companies like Quik Fuel etc for these. Using aftermarket, aka generic parts store kits, is not a good idea. The aftermarket kits use cork gaskets[leak city], needle and seats that use a big jam nut. These needle units are especially bad news as the thread pitch is off 1-2 threads and you can strip out your fuel bowl. If you want to do the low/no buck check valve here is what you do: I'm pointing at a small hole next to the throttle plate screws. On this carb, its a double pumper, the secondary is on the top and the primary is bottom. Since you are using a 2300 series carb, 2bbl, you only have one hole and that is only on the center carb. What you do is get a .203" diameter drill bit, open up the hole on the main body side of the throttle plate not the manifold side, by drilling down this hole to a depth of .180-.190" from the top surface. Drill a little then measure so you don't go too far. YOU HAVE TO USE A DRILL PRESS OR MILL! From there you use a small phillips that will fit in the enlarged passage and give it a couple of easy raps. This allows the vacuum to still reach the valve. Make sure the throttle plate is supported when you do this otherwise you can break it. What this will do is leave 4 small indentations at the bottom of the hole. If you got ahold of a carb kit, there is usually 2-3 ball bearings in it. They are different sizes. One of them will just fit this new hole. Put your plate to main body gasket on, right side up so it doesn't fall out. This is your new check valve. When it coughs or backfires, it stuffs the ball against the gasket and shuts the passage off. Read about this like 30yrs ago in a magazine or tech book and have done this mod ever since.
