very nice classic pattern engine here!
http://www.mecoa.com/index1.htm

look at this one!
http://www.mecoa.com/hp/61/2203.htm

All I get with that link is an opening page, no engine.

is HP all that? my uncle has a HP rear intake side exhaust (on the other side) up for sale now. he bought it in the mid 70's. i assumed decent performance but i don't want to see a collector's item get away.

What years were the HP .61's used most? I've got one NIB and would like to put it on a "period correct" airfame. Seems to me early to mid 70's but can't remember for sure as I was pretty young then.

I used an HP 61 in 1972-73 time frame. Replaced a Webra 61 Black head with it. Replaced the HP when the Webra Speed came available. Replaced the Webra Speed when the Rossi became available. Each was a noticable step up in power.

Hi Jeff,
On in our RC model club one member had a HP 61F RCwith "blue top" - he bought it new in early 1970th, probably 1972-1973. He had it in a Svenson Fly Boy to start with and then in a Midwest Mach 1.
It was one such HP 61 F RC, almost NIB, (not blue head but same otherwise) for sale at ebay some weeks ago and I made a bid on it but was not at home when bidding was near to close so I had no chance to bid higher - and I lost the bidding (of course...). It was sold for $188. Picture of that engine sold on ebay below. Is it same engine You have?

/Bo

Sorry Bo, no. Mine is the .61 Gold Cup.

Thanks Burtona, very helpful to see the progression in power. A Mach 1 or Nutcracker might be right for the HP.61.