From its earliest beginnings in 1902 as an automobile manufacturer, Holley has been all about creating carburetors that offer a greater level of performance. Half a century later in 1952, when the first four-barrel carburetors were introduced to the market on Cadillac V-8s. They were the Carter WCFB and Rochester 4GC and found their way onto Chevrolet passenger car V-8s as a performance option when the 265-inch small-block engine was introduced in 1955. The four-barrel Power Pack option included better flowing "pyramid" heads with a 9.5:1 compression ratio compared to the standard 8.5:1 compression ratio equipped with a Rochester two-barrel carburetor. On the other side of the fence, Ford offered a Holley four-barrel carburetor as a performance option for the Y-block V-8. In 1956, Ford was the first manufacturer to introduce light-duty trucks available with a high-performance engine option. Surpassing the '56 Chevy trucks, offered only with a detuned version of the passenger car 265-inch V-8, Ford made the larger 272-inch Y-block engine available in three stages of tune. The standard option V-8 is known as the light-duty 2V 272 (two-venturi, two-barrel carb), and the truck's original engine can be identified by locating a V in the VIN number on the aluminum serial number tag held on with four Phillips screws located above the lower hinge pocket on the driver side. If the tag is missing, as they often are, look for the VIN number stamped into the topside of the passenger-side framerail right in front of the firewall. If all else fails look at the VIN number printed on the pink slip (title).
Next up is the Z code heavy-duty 2V 272 identified with a Z in the VIN number. One might suspect heavy-duty means the engine has a heavier bottom-end, but as we've been informed it refers to larger-valve cylinder heads with better porting. Top of the line is the R-code 4V 272 equipped with a Holley four-barrel carb and the good heads. Of course the odds of a '56 Ford pickup still having its original engine are slim, but in the case of our one-owner Barn Find '56 we know the pale Ford Yellow short-block is the engine that came in the truck. Since there's a V in the VIN number, and the heads and four-barrel intake are factory painted in an original 292-inch Y-block Red we know the R code upgrade was added at a later date by the original owner. We've yet to discover a real R-code '56, so they must be rare, but it's interesting to note there never was a letter or digit in the '56 VIN to prove a truck with a Big-Window cab came from the factory that way.
What all of this has been leading up to is we decided to swap-out the vintage "square-bowl" Holley four-barrel carb we inherited and slap on an Original Holley Performance 390-cfm Four Barrel Street Carburetor. The new Holley is the best way to gain extra horsepower, get better fuel-economy, and lower emissions for any application that requires a smaller four-barrel to ensure it won't be over-carbureted. Read on and we'll explain what the benefits of the square-flange model 4160 Holley are for the Y-block Ford engine and how we went about installing it on our 272.