@Rob Fridenberg posted:Marlin - how do the secondaries affect idle and main circuit when throttle position has not engaged them? Isn't that governed by carb CFM and jet size??
My Quickfuel carb w/mech secondaries came with 3 links to control when they open based on throttle position. You can have 1:1, 40% and 60% throttle position to control when they come on based on your driving type.
Appreciate your thoughts - thanks!
...whether it's a 'Double Pumper' (Mech. Secs) OR a Vac. Sec. Carb, Most all Holleys have a 'Set' Idle SCREW* on the Secondaries. Accessible from the Bottom, only when the Carb is OFF the Manifold, Or You have a very Small (common) Screw Driver, BENT at a 90 Degree Angle. The Tiny Screw is Slotted. The Secondary Idle Synchronizes with the Primaries. The Sec. Throttle Idle is adjusted so the Blades JUST Uncover/expose the 'Idle Transfer Slots' (2) *. NO more! Then the Idle is 'Finalized' back at the Primaries. These Slots can only be seen when the carb is off the manifold.
All Others' Contributed Recommendations, are words of Wisdom!! Yes! As mentioned, a Bog Off-Idle, 9 times out of 10, it WILL be the Accelerator Pump!! And, there are SO Many, Different, Adjustments that can be made There! One Must do their Homework and Study, and with 'Trial and Error', home in on the Ideal Settings. ALWAYS...One Adjustment at a Time!! So You know which made a Difference, and You can 'Go Back', and try another adjustment.
* NOT to be confused with a Idle MIXTURE screw! Mixture screws control the fuel/air ratio, and are located on the side of the Metering Blocks. The Secondary Idle SET Screw, will Add to the control of the RPM.
** This is what Activates the Secondaries to Contribute to the 'Total' Idle. The Secondaries are Never Deactivated.
I like the Idle on My Cleveland at 900-1000 RPM. Keeps the Oil Pressure Up, and Makes taking off from a stop much Smoother.
All in All, Good-Luck with It!
MJ