Hello Dalton,
Floyd is correct in his comments. The early side port Camerons on spark, looked very much like the Ohlson 19 and 23 sideports. But that is where the resemblance ends. They were of excellent construction and materials, a quality product, quite unlike the Ohlsons and more powerful to boot! The first of the FRV glows were made for the Cox car operation, before Cox started to make the famous line of Cox engines. The later .15s were again very well made but not exactly powerhouses. They came in both lapped and ringed versions. The Cameron brothers stayed in engine production for a very long time, closing down in the late 60s if my memory is correct.
Enjoy the engines for what they are, a very well crafted and long lasting product. if not quite in the top league for performance. I would not part with mine!
Regards,
Andrew