Mystery Engine Found in Mayflower

["Dave Moag" <moag@ix.netcom.com>]

I visited a friend today who is beginning a restoration of a Mayflower. It
appears to have a strange engine in it. On the LHD side it has MOWOG and a 3
under it, and a big 1500 stamped in it. On the RHD side it has Pat. No.
565391 and a serial number 15GC-U-H 18911. The head has 3 exhaust ports and
2 intake ports. Does this sound familiar to anyone?

Thanks,

Dave Moag
62 TR3B
77 Spitfire