B40 O'head 8 hiccups.

[roscoe]

Hi Guys, I require some help please. I'm a first time poster. Problem being my B40 /ARF Cardinal combo suffers engine run hiccups during the overhead 8. The plane has had around 150 flights using a brass uniflow wedge tank/ 11x 5 prop 11/11/5% fuel / #4 ASP plug / s.t. nva.all good except for the above. But wait there's more!!! Today I flew 8 flights using a 6 oz uniflow clunk tank. In the air ; inside loops speeded up and during the last 3 minutes of the flight  the run leaned out. Adjusting the needle/ tank height produced more of the same in varying degrees, The best runs happened after the tank was mounted on it's side. Also I had to clean out the needle today to get the engine to run on the ground . Any help in obtaining a consistent engine run with this set-up would be most appreciated.  Thanks in advance Roscoe

[Steve Helmick]

If you get the rpm up a bit, it might stop. The 10.5 x 4.5 APC is currently the best cheap prop available for the B.40 and .40LA. Some de-pitch it to 4.0", depending on altitude.

Sometimes, a fuel filter will cure burps from fuel starvation, but sometimes they will leak and make things worse. I'd avoid any brass tank, for corrosion reasons. If using a uniflow, I'd put a filter on the vent to prevent stuff from going into the tank. Otherwise, it sounds like you have fuel tank or fuel handling problems you need to work out. See what the Experts do...how they get the fuel out of the jug or can, how they get it into the tank, how many filters are in the system. There's a good reason for it, and it came about from bad experiences. Steve

[Wayne J. Buran]

The 10.5X4.5 APC is the best prop for the B-40. I would also suggest the the problem is in the brass tank. As for the plastic tank I would say it still needs some tweeking. My B-40 rum\ns like a watch in my Smoothie. Never a hitch.
Wayne

[W.D. Roland]

sounds like you need fuel filter  and or clean fuel for one problem.
the hick up probably is not trash.
posibly re aim spray bar?
possibly re route fuel line?
and what 35tac and Steve said
 if it hickups when chancing directions possibly a shallower tank to reduce changes in fuel delivery due to g-force changes?
make front of tank higher or lower in relation sip to rear?

let us know what cures it please!

me duno as i am a new old flier that reconizes verry few of the engines talked about these days

 David

[Ralph Wenzel (d)]

The 10.5X4.5 APC is the best prop for the B-40. I would also suggest the the problem is in the brass tank. As for the plastic tank I would say it still needs some tweeking. My B-40 rum\ns like a watch in my Smoothie. Never a hitch.
Wayne

That prop may be right for your particular plane/engine/fuel/etc. combo, but don't be quite so certain until you've tried a Rev-Up 12-5 cut to 10 1/2 inches.  Due to "slight" ground contact damage, I had to switch to the APC one day, and it was horrible; All my turn vanished! This was also on a Cardinal.