At a swap meet, I was hanging around at closing time hoping to get some deals from guys not wanting to cart their stuff home. One of the things I got at closing time for $50.00 was a .40 sized RC Trainer plane. It came with a brand new radio and had a Saito FA-40 engine mounted. I’ve always wanted to try 4-stroke engines, so it was a good starter deal. I’m thinking I’ll fly the engine on the RC plane a few times to get some 4-stroke experience, then move the engine to a CL plane. I spent three or four hours last night reading up on the older Saito 40 engines. I understand that they were heavier than the 40A, but an engine in the hand…
I’ve read through Bob Reeves’ Saito 4-stroke modification of making a new barrel and trimming back the spray bar a couple of times. Unless I’m totally confused, the main purpose of the modification is to be able to match the volume of air intake to that required for the size prop being used. In the modification, it is done by screwing the nylon bolt in or out. I do not have the lathe to do the mod myself, and it seems excessive to spend more on having the mod done than I paid for the whole plane outfit. So, I was wondering about effectiveness of a different method. The FA-40 that I have has the factory installed slide choke. If I use that to incrementally limit the air intake, will this have an analogous effect to doing the nylon screw mod?
Also, Bob’s article says to only use props with an effective pitch of 6 ½ or more, and then goes on to recommend the Rev-Up 11 X 7, Thunder Tiger 11.3 X 6.5, or Evolution 11 X 7. Can someone define “effective” pitch versus stated pitch? Are these props still the best recommendations for the early FA-40 engines?
Bob says to set the choke to a point that lets the prop turn 8000-8500 RPM in flight. Is that for the .40 as well as the larger engines? What static RPM gives an in-flight RPM of 8000-8500?
The statement, “If you are running over 7 minutes on 4 ounces (3 1/2 on the 40) something isn't right.” Not sure what problem this points to?
On setting the needle and choke, he starts with setting the needle on the rich side of peak. I assume the initial setting is done with the choke fully open? Initial setting done with one of the recommended props above?
I suppose those are all the questions I have for now,
Mark