Franklin Engine Modification

Follow Ronald McClellan through building the carburetor and replacing the air intake for the restoration of his Franklin gas engine.

| June/July 2020

McClellan’s engine with a carburetor fabricated from an old soda-acid fire extinguisher.

I bought an engine the end of April 2019. Cast on the base is “Franklin Gas Engine Patd.” Everyone knows these engines as Parsell & Weed engines. I have the vintage book Gas Engine Construction by Henry V. A. Parsell, Jr. and Arthur J. Weed, dated 1900. It gives detailed instructions for building a 1/2hp horizontal or vertical engine.

The engine name is cast on the base.

The design and castings were supplied by The Franklin Model Shop owned by Parsell & Weed. These engines were Franklin engines and were not called Parsell & Weed until modern times. It weighs 92 pounds. It has 14-inch flywheels with a 2-1/2-inch bore and a 4-inch stroke. It would be interesting to know who, why and when the name change happened.

Two check valves are mounted on the head.

When I got this engine there were things that didn’t look like the other engines that I have seen. At first glance, it looks like it was made into a compressor. It had two large check valves mounted on the head and a poppet valve in the head. The pushrod for the valve was normally run off the timing gear as an eccentric. On this engine, there is a cam to operate the poppet valve. That made it necessary to make an arm to support the pushrod.


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