This old vertical intake PAW 249 runs very well, but unfortunately leaks like a sieve between the top flange of the collector ring, and the adjacent surface of the lowest fin on the cooling jacket.
http://www.youtube.com/watch?v=YhqOwEvcOlg
This engine was given to me from a deceased estate (ref. my earlier thread "diamonds in the rough"). It is very well made with first class materials and exemplary working fits. Compression is excellent despite it's strip down and re-assembly. A real credit to Gig.
The let down is that the lowest fin on the cooling jacket has been crudely filed away. The bottom surface is not trued. I suspect the engine was originally sold without the exhaust collector, then added by the owner at a later date with his own cutting down of the lowest cooling fin.
I will either skim and true the bottom surface of the lowest cooling fin and make a thicker top gasket to take up the clearance, or enquire with David Owen about a new cooling jacket. That would be a pity. The current cooling jacket has an ideal "tight slip on" fit promoting efficient thermal transfer.