I have a profile Cardinal that has the universal mount from Brodak so i have been trying different engines out. ST 46, LA 46, and others all run the way they are supposed to. Yesterday i mounted a Stalker 46 and had an issue with what sounds like it going dead rich when you point the nose down. Lap times were even so I'm pretty sure tank height is correct, prop was a XOAR 11 x 6 and Rev 11.5 x 5, both worked pretty well and lap times were 5.2 to 5.4 The engine breaks everywhere like it is supposed to EXCEPT like on down leg of outside squares and when you hit the turn to inverted on the reverse WO. As soon as you hit down it just seems to go really rich, like a burp but not a burp. It responds back pretty quickly and only seems to do it on the first turn...after that is seem OK. I tried uniflow with press, uniflow no press and vented, all about the same.
Set up is:
Stalker 46 SE (new ones from Tom Dixon) not sure if they are the same as the ones i had back inthe 90s. It is a baffle piston but I thought my old ones were iron piston..don't remember really
Thunderbolt RC long plug
RSM 4.5 oz uniflow tank
XOAR 11 x 6 prop
stock needle valve
stock venturi...not sure what size it is...yet, will measure tonite.