Re: Concerning Bubbles & Vapor Lock

Posted by TxGoat On 2023/5/19 8:35:42
Inline engines most certainly do suffer from "vapor lock", flooding, carburetor boilover, etc. It's very common among inline engines with downdraft carburetors and fuel pumps located on the manifold side of the engine, which is most or all of them. The problem is aggravated by many modern "fuel blends" which are not designed for carbureted engines with vented fuel tanks. Flathead Mopars used a fuel pump heat shield, as did many other makes, including Packard. Pontiac 8s used a metal shield under the carburetor base to deflect manifold heat, along with a heat insulator under the carburetor. Packard used special non-metallic bushings on some fuel pump mountings to reduce heat transfer from the engine block to the fuel pump. It's true that V8 engines, especially large 1950s V8s with air conditioning, suffered form heat-related fuel issues, but it was not and is not exclusive to them. Flathead Ford V8s were handicapped by a high-mounted fuel pump, but that was offsedt by the fact theat the exhaust manifolds were located under the block awqay from the pump. Some Lincolns had the fuel pump mounted high on the front of the engine directly behind the fan. They'd vapor lock in hot weather after being parked. "Winter blend" fuels would aggravate heat related fuel system issues in warmer weather, and fuels today can be very problematic in some areas in warm to hot weather.

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