Z28 Holley Carb - Calibration Database for List No.'s 3910, 3911 & 4053 Carbs

[COPOZ/28]

My current Camaro project has been to pull together a database of all of the specifications that affect the calibration on the OEM Holley 780 carbs that Chevrolet used on the 1967-'69 Z28 302 engines, Holley List No.'s 3910, 3911 and 4053.  The database includes many key features that were never published by Holley in their Numerical Listings or by Chevrolet in their Service and Overhaul Manuals or in any of the Holley Rebuild/Tuning books out there.  This would include various calibration features Holley incorporated in each of the specific carb bodies and metering blocks for these three List No. carbs, such as: PVCR hole diameters, Idle Feed Restriction hole diameters, Idle and High Speed Air Bleed hole diameters, etc. etc.
 
The purpose for pulling this data together is to act as a definitive source that would allow owners of these early Z28 carbs to determine if their particular carb has been modified from the OEM calibration condition by virtue of a previous owner who may have gotten a little overzealous with a drill and "attacked" one or more air/fuel calibration passages in either the metering block or the main body.  I am hoping the CRG Moderator will consider posting the database, when complete, in the appropriate section on the website, as a supplement to the very helpful Holley four-barrel carb info already posted there.
 
The database is 100% complete for the List 4053 Holley, used on all '68 and '69 Z28's sold in all 50 states.  This carb was the "easy" one to do, since I own an unmolested 4053 carb.
 
However, in order to complete the database (which has become a labor of love), I could use some help from owners of unmolested 1967 Z28 Holleys: either the List 3910 carb (used on all non-California sold cars) or the List 3911 carb (used on all A.I.R. system equipped cars sold in California).  I'm hoping to find a willing soul or two who would agree to work with me, and who ideally also owns a set of small number drill bits, to carefully probe a few specific drilled holes in their metering blocks and/or main body.  To access many of these calibration holes (PVCR, Idle Feed Restriction, Emulsion Well Bleeds, Main Well Siphon Break) it will require removing the fuel bowls and metering blocks from the main body.
 
If anyone steps forward to lend a hand in this endeavor (and who has access to a set of numbered drill bits or small gauge pins covering the range from 0.020" - 0.070" dia.), I will walk you through what would be involved in gathering the missing data needed to complete the database for their specific List No. carb.  In the event a volunteer steps forward but does not have access to these small drill bits or gauge pin sets, I will mail/loan you my set to use,  although the #1-60 and #61-80 sets are very reasonable (< $30) to purchase via mail order).
 
I've been in contact with many sources to date to get the database to the point where it is today.  This includes Engineers/Techs at Holley, knowledgeable Holley people at various Holley restoration facilities, and many others.  Recently, I've been in touch with Jerry MacNeish, a long time CRG Member, who is all for completing this database as it will be of significant help to 1st Gen Z28 owners hoping to accurately restore/return their carb back to the calibration it had when it left Holley.  Who can argue with that endorsement?
 
Until such time as the database for all three carbs is complete and (hopefully) published on the CRG website, if anyone who has a List 4053 Holley on their '68 or '69 Z28 and would like to know what the original hole diameter should be of any of the metering block or main body calibration holes, just send me a private message and I will gladly help you out in any way I can.
 
Thanks for reading and many thanks in advance to anyone who volunteers themself and their carb to help complete this database.  I'm posting this in the "Restoration" category as well.
 
Chuck B.