I have used 4 stroke engines as much as most people and have established a number of guidelines.
I have NINE 4 stroke powered planes at this time, one of which is powered by THREE engines.
I use Brodak 10%nitro, 23% total oil in all my 4S engines EXCEPT for my non-Surpass OS .40. That one likes 20% nitro.
Except for my SAITO .56, I use metal tanks without uniflow.
On my profiles, I use open venting - no muffler pressure. I run a single vent to the forward inboard upper corner of the tank. I bend that vent forward into the slipstream.
On the triple, I use the old Perfect over/under vented tanks and the runs are perfect.
On my inverted engines, I use the same single vent metal tank setup but with muffler pressure.
Glow plugs - now here's an eye opener. I have tried just about every brand on the market and I have found NO DIFFERENCE!!!
I have four SAITO .30s and the first one I bought, around 6 years ago, still has the ORIGINAL plug. I don’t even know what brand it is.
Regarding props: This, as is well known, takes some experimenting. For most applications, the APCs seem to work best. I run a 10-4.5 on my SAITO .30 in the Argus. All the others get a 6 or 7 pitch.
The non-Surpass .40 works best with a Master Airscrew 11-7 plastic.
When I was experimenting with my Euclid II, (Surpass .40), I tried quite a few props. The best was an AHC 11 1/2-6 1/2. With that prop, it flew the same speed as with an APC 11-4 but ran 2 minutes longer. Go figure.
I have the prototype Brodak P-40 ARC and have tried a number of engines. The last one, a Diesel, turned out to be a disaster.
It will get the original SAITO .40 back. It was perfect with it.
Bob Z.