ckessel
Well-Known Member
I put this on my 65 thread but for those who don't view that, here is a separate thread.
Many years ago I read about a simple, no dollar way to put a check valve in the throttle plate passage that the power valve gets its vacuum signal from. You can do this on 2300's[ six pack etc], 4150's[ double pumpers or vac secondary with metering block in rear], 4160's[ metering block in front, jet plate in rear]. In the Holley kits, there is a ball bearing in the small parts bag. It's .185" in diameter. Where I'm pointing with the screwdriver is the passage, on the primary if only one valve or back on the secondary if two, that gets drilled. You need a .187" [ 3/16"] to .203" drill bit chucked up in a drill press with the throttle plate supported on the back side. You drill this passage .190" to .200" deep. After that you take a small Phillips driver or bit, place it in the hole and give it a couple of light whacks. Again with the plate supported on the backside so you don't break it. These small divots allow the valve to receive its vacuum signal still. Place your gasket back on the plate to hold the ball in and put it back together. When the engine sneezes/coughs/backfires, the pressure forces the ball up and thereby closes off the passage.
I scored an older 3310-2 at Woodley recently to replace the Street Avenger on my wagon that doesn't want to lean out. Since I remembered this mod, I did it on the new/used unit before it goes on the 440.
Many years ago I read about a simple, no dollar way to put a check valve in the throttle plate passage that the power valve gets its vacuum signal from. You can do this on 2300's[ six pack etc], 4150's[ double pumpers or vac secondary with metering block in rear], 4160's[ metering block in front, jet plate in rear]. In the Holley kits, there is a ball bearing in the small parts bag. It's .185" in diameter. Where I'm pointing with the screwdriver is the passage, on the primary if only one valve or back on the secondary if two, that gets drilled. You need a .187" [ 3/16"] to .203" drill bit chucked up in a drill press with the throttle plate supported on the back side. You drill this passage .190" to .200" deep. After that you take a small Phillips driver or bit, place it in the hole and give it a couple of light whacks. Again with the plate supported on the backside so you don't break it. These small divots allow the valve to receive its vacuum signal still. Place your gasket back on the plate to hold the ball in and put it back together. When the engine sneezes/coughs/backfires, the pressure forces the ball up and thereby closes off the passage.
I scored an older 3310-2 at Woodley recently to replace the Street Avenger on my wagon that doesn't want to lean out. Since I remembered this mod, I did it on the new/used unit before it goes on the 440.
