Hey all,
Need some advice on when I can adjust my low end and change back to a 12x4 prop on my new 46 ax. Just got it today, did the bench breakin with a tank of fuel, and flew 2 tanks at rich settings with a 11x6. I'm wondring how long I should wait before I can switch props and lean out the lowend. The guttering makes me nervous, and I keep landing real hot cause I'm worryed about needing to punch the throttle if I need to abort landing and the the engine choking.
THanks
-John

Your good to go!

I guess I should elaborate a little...I do advise you to go ahead and put on the prop, but make sure you adjust the needle valve you don't want to run to lean. As fo ryour engine getting hot...it is normal for it to be so hot that it could burn you. No worries!

The engine isn't running hot, I'm landing hot As my low end is real rich and I'm worried about slowing down to much, having to abort, and the bad transition causing a Uh-oh
-John

Hi..

It is OK to adjust the low end so you have smooth transition from low to high. lean it out so you can have fun and not worrying about it.

You can lean it now...no problem.

I bought one of those and it's a great engine so far....it's in my shiny new 'beater' plane. Couple of rich tanks and off to the races....

Just curious - what are you pulling with your 46AX?

Ok thanks all. I'm pulling a PT40. I killed my fx unfortunatly Had a crack in line between carb and needle valve I discover'd a few weeks ago, and I'm guessing that lean'd out the engine and recked the cylinder. Can read about that further below in this forum So I needed a new engine, and got the ax cause from all I hear it's a great little engine, and I didn't have to modify my cheeks any to fit it. Now once the rain that comi'sng goes away I can refit the 12x4 lean out the low end, and go fly. Plane was feeling a bit odd today. I need to check my balance.
Thanks again all
-John

Sorry to hear you had to resort to a full replacement but you'll dig on that AX. I've got it in my LT-40 and it cruises good at 20% throttle and a 12x6... full throttle rocks.

somegeek

If the "bench breakin" showed that the engine would hold a good solid wide open throttle without sagging, you could have started adjusting the low speed needle right then.

An ABC engine gets little or no benefit from running it with a rich low speed needle setting. It's not going to be generating heat near idle like it does flat out. So protecting it with an over-rich low end is sort of a waste. Combine that with an over-rich needle valve adjustment and you're not only wasting fuel but risking a flameout while you're landing.

As long as you always open the needle to be absolutely sure to see a 4cycle during the first run of the day (and then of course lean that needle back to your optimum setting), your AX is going to be happy and you're going to have that sucker for years to come. And it'll benefit from having a proper low end setting from the git go.

BTW, I've dealt with at least a dozen 46AXs this year and almost all of them work really good with 11x6 and everybody that tried an 11x5 was happy with that. The 11x5s give you a slower landing speed (by roughly 20%) and a bit better pull going uphill. If the airplane lets the engine work happy with a 12x4, that prop will usually give even better pull uphill and the landing speed should be even slower.

If I were you, I'd adjust the lowspeed needle a bit now before going to the 12" prop simply because larger diameter props help the idle so much that they sometimes hide poor lowspeed needle settings. Of course, once you have the 12" on the engine, don't stop looking at how it idles and the settings it wants.