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Question for the Timing / Fuel Experts....

On all the two fuel bowl four barrels I've seen, the secondaries are open slightly and provide some flow - this is to make sure the fuel in the secondary bowl stays fresh. So, the blades should be slightly open - check the specs. I know my Summit 600 has them slightly open.
 
Looking down the throat, the secondaries appear closed on mine but I'd have to pull the carb off to verify.
 
The opening is normally very small, a few thousands at most. Some carbs use a stop (Holley, and perhaps the Summit, I forgot to look this w/e), some use an interference fit (webers) in the bores. However, it's important to remember that the secondaries operate pretty much the same as the primaries, and while they may not have an idle screw, they do have transition slots / holes, and need a small flow of fuel to prevent lag & gumming problems. If the blades are not closing as much as necessary, it can be metering fuel from the secondary transition slots, and closing the primary idle screws will not cut off the fuel. Being open another .020 could cause this, but is unlikely to be visible from above IME. Check the linkage for binding, etc. and finally pull it off to look.


Edit: the Summit uses a set screw to set the opening. See Fig 3a on Pg 5, and Fig 8, Pg 9. These show the set screw, just below the vac diaphram. Also, this on Pg 11:

SECONDARY FLOAT LEVELS:
Very little fuel is drawn out of the secondary fuel bowls during idle operation.
Click to expand...

http://static.summitracing.com/global/i ... 0instr.pdf

No spec listed for secondary blade opening that I could see, however.
 
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