We all know about the Stromberg 81 carburetor, right? The 97’s smaller brother. Standard fit on the infamous ‘thrifty’ Ford V8-60 motor from around 1937 to 1940. Designed with a tiny 0.81 inch diameter venturi and 1.0625 inch throttle bores. Rated at various different cfm (cubic feet per minute of air) depending on who you talk to and whose equipment you test it on. Hard to find. And pricey too, nowadays. Yet more importantly, holder of almost legendary status among the 4-banger (and V8-60) cognoscenti.
Why? Because two of these babies on pretty much any 4-banger Ford motor (or V8-60 Midget for example) is, and has always been, the sweet set-up if you want both high performance AND road-going flexibility. In short, the smaller 81 venturi are better suited to the smaller engine size. Two 97s might work great on a flathead Ford V8, but stick them on a smaller engine and they will see far lower vacuum at the carburetor (same straw – smaller lungs). Use carbs with smaller venturi and they will see higher vacuum, which helps maintain quicker air speed/throttle response when you open up from lower rpm.