Yes I have on many occasions. The 600 CFM 4010 series Holley that I have, I received on a trade for an early 4300 that I put together about 12 or 13 years ago. It was a good deal, that 600 was brand new out of the box, I couldn't believe that he wanted to trade.
I have been studying the fuel path pretty closely for the secondaries. It begins behind and to the left of the power valve with a hole in the fuel bowl and heads up what becomes a brass tube into a well in the carb top. This is where I encountered the first air bleed, I am assuming that this is kind of a vacuum break to keep the fuel from siphoning up this tube too hard. The fuel then heads down into a hole in the carb body right beside the brass tube, and transfers over to the secondary side through a channel between the 2 primary barrels. It then branches off into the 2 secondary fuel wells where it feeds the 2 secondary boosters as needed when the secondary butterflies open and the pressure differential is created to cause fuel flow through the boosters.
At each booster there is one air bleed that I assume forms an air assisted atomization system with the booster. I haven't determined what the brass tubes are for that come out of the bottom of the boosters, but I suspect that they provide early fuel flow to help prevent a stumble when the secondary butterflies open.
I have a junk top that I have been experimenting with. I noticed that the brass tubes in the center of the secondary boosters had a screwdriver slot in the end of them, I removed the plug in the carb top, and inserted a screwdriver in the hole, and removed one of the tubes thinking that maybe a jet was hidden behind one of these, but that was not the case.
So, how do you enrich the secondaries on these? I might not actually NEED to on the application that I am going to use these on, in fact I may find that I need to lean them out a little, so I guess that the appropriate question is how do you ALTER the fuel being provided by the secondaries on these carbs?
There is almost no information available for modifying these carburetors, so I am relying on my knowledge of how other carburetors accomplish their metering goals and making some assumptions as to how this is accomplished on these, how am I doing?
@94 1/2 MPH
1.49 60 ft.