20601 Old State Road, Haubstadt, Indiana 47639.
Starting in 1923, the sorting of Hercules built engine models and sizes becomes somewhat confusing. Beginning on March 1, 1923, both Jaeger and Arco engine brands came equipped with the Wico high tension magneto and spark plug ignition system. The small block Jaeger was rated at 2 HP with no model designation on the tag. The small block Arco was also rated at 2 HP, but it had model FW on the tag. This all begins around serial number 260,000. Later in the year at around 293,000 serial number the small block Hercules and Economy engines became equipped with the Wico ignition system; however, they continued to be rated at 1 HP with FW on the tag. The FW designation also was used on the larger size engines as they were switched to the Wico system; however, the 5, 7, 9 and 12 HP sizes used the larger Wico PR magneto rather than the smaller EK.
Parts books make no mention of the FW model skipping from the F to G model. The short lived G model appeared in 1924 and as far as your writer can tell it was limited to the Hercules and Economy brands. There appears to be no mechanical difference between the FW and G models. The FW model was phased out of all sizes by number 306,000.
To complicate things further, two new one piece frame engines were also introduced about this time. One was the 2-2 HP size with a 45/8 inch bore and 5 inch stroke. The other was a smaller size 1 HP engine with a 4 inch bore and 4 inch stroke. Both of these used some parts common to the usual small black Hercules built engines. These will be discussed in more detail later on.
When the Wico system was introduced the patent had yet to be issued on the #2 magneto drive mechanism. The patent wasn't issued to Wico until October 30, 1923 and that date is made into the trip housing casting. The accompanying illustrations show these first Wico systems used on Hercules built engines. Note that the side rod brackets are a one piece casting. They were soon redesigned to a two piece part so that adjusting the timing was much easier. Several other brand engines besides those built by Hercules also used the #2 drive.
Around serial number 300,000 several small block Jaeger engines were built with the spark plug in the head. The magneto bracket was blank at the normal spark plug location. The exact reason for this is unknown, but it may have had to do with allowing operator access due to some particular way the engine was mounted on the concrete mixer.