Big Washburn Carb Windows: What They Are and Why We Cut Them

A "big carb window" is what we call the oversized rear apron cutout we open up on a Beetle so a tall single carb (45 DCOE, 48 IDA, big linkage on a Solex) clears the engine tin and the apron with daylight to spare. The factory hole is sized for a 30PICT - cute, fine for stock, but it crowds anything taller and it's a pain to thread linkage past a sharp inboard lip.

We cut the window with a metal-on-metal stop block clamped to the apron, run a step bit to start the corner radius, then a pneumatic shear walks the rest. The carbon fiber cover that bolts back on (BY01-CF in the catalog) is the reason we ship these as a kit instead of telling people to swing a sawzall - it puts a finished edge on the hole and replaces the metal you took out so the apron stays stiff at the trans mount.

Why bother if your carb already clears? Two reasons. One: heat soak. With the window open and the cover panel sitting 3/8" off the metal, you get the same airflow the dual-carb crowd has been using for years - the float bowl temp drops 40F at idle in our Orange shop. Two: serviceability. You can pull the carb top with the engine in the car. Stock window, you can't.

Fitment: '58-and-later Beetles, all single-carb installs taller than 4.5". We've also done it on Type 3s with the squareback shroud, but those need a slightly different cut path - call before ordering.

Brian