what size carbs??

[RobMcQuarie]

MrMike, the Holley carbs you refer to were a re-issue of the factory Ford 2-4V carbs used by Ford on 2-4V 427's and 428's from 1963 to 1967. They are vac secondary, have the front metering block and secondary plate, correct side lever design for the dual quad linkage, correct vac diaphram covers for dual fours, and are calibrated for dual four use on the street. Remember, Ford sold these on new cars, to the public. They had to perform very well, with out causing warrenty problems. They were specifically designed and calibrated by Holley for good overall street performance.

One thing very few people understand, is that carburetor air flow is rated differently. For example, a 500cfm 2V carb only flows 333cfm when rated the same way a 4V carb is rated-1.5" vs. 3" of mercury. Similarly, multi-carb set-ups do not flow what the sum of the carbs would indicate. Ford new this when designing all of their mutli-carb set-ups in the sixties. Obviously, a stock 427 or 428 engine with 1100cfm would seem to be overcarbureted. But it works very well, and Ford put even bigger pairs of carbs-652, 715, and 780cfm-on the hotter engines. An indicated 1100 cfm works as if it is really closer to 750-850 cfm. Likewise, the dual 450's at 900cfm total act like a 650-750 cfm carb. So one is not really as "overcarbureted" as one would beleive with 2-4V set ups. What often happens though, is folks bolt on a pair of 1850's, without more than a jet change, and then unfairly blame the 2-4V set up overall when running into driveability problems. Dual quad carbs were calibrated for the application.

But, as you know, original Ford 2-4V carbs are hard to find, and when located have 30+ years of wear. They typically need extensive restoration work on top of their initial price. Holley actually discontinued the 80431/32's a number of years ago, even though they were in the catalog.
On the 2-4V's we set up for our customers, we have been either custom modifying the generic 450 and 600 Holley's, restoring original carbs, or using some re-issue C3AE-9510-BJ/BK (550cfm) carbs that Holley made for us a few years ago. They are basically the 80431/32's, but with factory Ford numbers. They work great, look "original", and have all of the correct linkage attachments, etc. So there are a number of carburetor choices when setting up a 2-4V, depending upon the individuals preferences. If you really prefer the factory BJ/BK Holley's, drop me a line, as I have a few sets left.