The flywheel is 3.5 inches in diameter... Overall an unusual and nice old steam engine... The item "ANTIQUE Vintage Vertical Live Steam Engine Stuart or Unknown Maker 7.5 Inches" is in sale since Wednesday, November 23, 2016. This item is in the category "Business & Industrial\Light Equipment & Tools\Stationary Engines\Engines". The seller is "gypsiegirlz" and is located in Healdsburg, California.This item can be shipped worldwide.