Thank you Bruce. More mass is the ticket for damping vibration. That is why so many well done Lister (and other) engine installations start with a huge lump of concrete! I wanted a sturdy, heavy base but I do not have a permanent home for the engine. Someday I hope to build a proper "engine room" for these to reside. So, until then, it has to be heavy to be smooth, and semi-portable.
A requirement was to follow the Lister recommendation that the crankshaft be 23" above the ground. This is in the installation section of their manual. Easier cranking and a convenient height for maintenance, service, and inspection. Who am I to argue with them?
Next, use what materials are available or on hand. The local steel dealer had the 12x1 HRS that became the I beam web The flanges are 1/2 x 3. The spacers between the I beams are solid steel bar stock left over from a job I did years ago. About 3.5 in dia as I recall. I drilled and tapped 3/4-10 into each end and made the spacers. The rest is using what was on hand. The radiator is a Ford 8N tractor rad off of ebay with rubber mounts from McMaster. The legs are salvaged 3X5 square tubing. They also make it easy to move it around with a pallet jack or forklift.
The generator slide mount is very simple and works great. A inexpensive pillow block, threaded rod and a crank from some scrap machine are those pieces.
I have detailed pictures and a few (not all) AUTOCAD drawings if anyone wants more information.
If I went through Butch's procedure for balancing it would be even smoother. I might have to twist his arm next summer.
Bob