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New (to me) Supercub... Running hot? Charging issues too

Happy to report..

First flight today with new bayonet CHT probes.. and and EDM350 monitor.

I saw cruise CHT at 380s. I saw 402 on a Vx climb much higher that I needed it.

New fuel flow gauge..my 160hp o-320

I got 10.5 gal/hr on take off (after liftoff, as it wound up) .

7.5 or so gallons an hour at 2400rpm.

leaned out to about 75 rich of peak... 6.6 gal/hr

SEEMS like I believe all these numbers much more than the previous gauges. My 3 is still the hot one... but it's much better.

JP
 
You should be burning more fuel than that wide open on take off climb,
Is your fuel flow calibrated correctly?
if so, you're too lean.
 
You should be burning more fuel than that wide open on take off climb,
Is your fuel flow calibrated correctly?
if so, you're too lean.

Brand new computer and fuel flow setup. I'll take a look at the book on setup and see if he missed anything. This winter we drilled the main jet out bigger. Plugs all look pretty good. I could fill a tank and run that one exclusively and fill back up to check flow number.



JP
 
No need to run a tank dry. Top a tank off (yourself), run min of 10 gal then top it off to the exact same spot in filler neck. Compare what you put back in the tank to what your meter said. Ambient temp should about the same when you go to refill.
What brand fuel flo devise do you have? I'd be surprised if it doesn't require calibration to your application. Too many variables in fuel systems for one size fits all.

Rule of thumb - full rich, you should be burning almost a gallon per horsepower

edit: sorry, misread your last post, sounds like you've got the idea.
Also, have you checked leaning authority with your new probes installed?
 
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Thanks.. wasn't planning to 'run dry' though. Just go on a good long flight using one tank only.. and top off before and after.

Fuel flow was what came from options on aircraft spruce for EDM-350

Not sure how it works.. but I'd imagine it's some sort of 'paddle wheel' so it knows how much flows though... how would that change from one application to another??

I thought the plane was a bit slow today (indicated speed) but I only went for a short ride.

I did think the 7.5 at cruise sounded about right.. I was a bit surprised by the 10.6 or so on takeoff, I would have expected more.

JP
 
divided by 10. 160/10=16gph The Lycoming manual says 13.6 gallons per hour at 2700 rpm/160 hp.

I'm not turning up to 2700. Even level, full throttle I only got 2650. Prop is a 7454. Climb out was around 2500 at about 60kts.

Either way.. reading up a bunch of posts (mostly RV guys running 320s... It sounds like I should be more in the 13+ range.) . question is.. is it running that.. or is it running lean?

Pretty easy to figure out. Just take a bit of time.

JP
 
Go to sections 32, 33, and 34, in the installation manual. It explains the 'K factor' for the fuel flow sensor and how to check/adjust it to match actual fuel usage.

Web
 
Go to sections 32, 33, and 34, in the installation manual. It explains the 'K factor' for the fuel flow sensor and how to check/adjust it to match actual fuel usage.

Web

Was JUST getting back on here to say... Read the directions. You're right.. page 32. It pretty much says... take three LONG flights.. record the burn.. the REAL burn.. and reset the number. I think it's infinitely more likely that I'm burning the right amount.. and it's just counting it wrong. :)

Thanks. Typical guy. Go fly it.. scratch your head.. ask around.. when ALL ELSE fails. look at the directions. :)

It'll be a good excuse to put some time on. I need to do 5 hours with the new Whirlwind.. AND stay within 35 miles of home.

Two birds.. one stone.

JP
 
divided by 10. 160/10=16gph The Lycoming manual says 13.6 gallons per hour at 2700 rpm/160 hp.

“Almost” ;-)
ive heard this figure quoted before, seemed to ring true.
My (lycon) 160 cub burns 14.5 gph
Maule O540 23 gph

whats an educated guess on a general rule of thumb
for sea level carbureted engine?
 
“Almost” ;-)
ive heard this figure quoted before, seemed to ring true.
My (lycon) 160 cub burns 14.5 gph
Maule O540 23 gph

whats an educated guess on a general rule of thumb
for sea level carbureted engine?

There were lots of guys throwing out math on the RV forums. I want to say it was something like .54 or .56 POUNDS of fuel per HP per hour. So.. that means 300hp is 27 or 28 gph wide open. Sounds like that math works.

JP
 
A couple of thoughts. I have a 160 that ran hot. Do you have any intake performance mods such as ported and polished intakes? Engines that breathe good tend to run a little lean. I get 12.6 on take off. Second, since you have a good monitor, run it at less than 70% on the lean side of peak. I get mine about 15 to 25 lean of peak, makes about 10 degrees difference on CHT with no degradation in speed. With a 75/56 I run at 2400 at 4000 DA at a fuel flow of about 6.6 to 6.8. My hottest CHT (3 and 4 are the same) run about 380.
 
Random question: do you have a -12 or a -32 carb?

What’s your O-320-xx nomenclature?

The -12s run leaner than the -32s. Depending on your oil sump you may need a tapered adapter between the carb and the oil pan
 
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“Almost” ;-)
ive heard this figure quoted before, seemed to ring true.
My (lycon) 160 cub burns 14.5 gph
Maule O540 23 gph

whats an educated guess on a general rule of thumb
for sea level carbureted engine?
My post was only to adjust your rough rule of thumb calculation not meant to be precise.
My rule of thumb for cruise fuel burn is rated horsepower, drop the zero then divide by 2. 160, 16/2 = 8 gph. This is the rough safe fuel burn for flight planning.
Yes you can massage this by your personal operating technique. Running lean of peak, rich of peak or not leaning at all.
 
Random question: do you have a -12 or a -32 carb?

What’s your O-320-xx nomenclature?

The -12s run leaner than the -32s. Depending on your oil sump you may need a tapered adapter between the carb and the oil pan

I'll have to look at the carb.

It's an E2A motor

I'm pretty happy with the plane. Had it about 6 months now. Have put 50 hours on it.

Gotta finish up the EDM 350 probes. Put the whirlwind prop on. Put in a new windshield.

Maybe buy a second set of rims, and some 31s.

I'm pretty content. I'd never say i'm 'done' . but it will be pretty much what I had imagined. It's a far cry from my 100hp C-140 that was my first plane for 3 years.

Oops.. forgot the Clamars I'm looking at. But that's down the list after I save up for an older Prevost Bus.

JP
 
I'll have to look at the carb.

It's an E2A motor

I'm pretty happy with the plane. Had it about 6 months now. Have put 50 hours on it.

Gotta finish up the EDM 350 probes. Put the whirlwind prop on. Put in a new windshield.

Maybe buy a second set of rims, and some 31s.

I'm pretty content. I'd never say i'm 'done' . but it will be pretty much what I had imagined. It's a far cry from my 100hp C-140 that was my first plane for 3 years.

Oops.. forgot the Clamars I'm looking at. But that's down the list after I save up for an older Prevost Bus.

JP

I’m pretty sure (but not positive) that the E2A has a straight riser oil sump meant for the -32 carb.
 
I actually have next-to-nothing for carb knowledge. I just happened to have previously searched a similar question to yours.

Here's a thread that made a lot of sense to me: https://www.supercub.org/forum/showthread.php?41979-Carburetor-for-Lycoming-O-320-160

Applicable quote from that thread here:

I agree that you want a PA-18 airbox, but it will fit any of these carbs.

In my opinion, the advantage of the 10-3678-32 carb is that it flows more fuel at full throttle and therefore provides better cooling on climbs. It also has a unique economizer feature that leans the mixture somewhat at partial throttle.

An O-320 E series engine from a Cessna probably has a 10-5009 or 10-5062. These run leaner at full throttle than the -32. This can be fine in a Cessna because it has a better cooling system than a Cub.

Replacing a carb can be pricey. I would try the carb you have but keep a watch on the CHTs during climb. If they are getting hot – over 400 – I would ream out the main jet a little and try it again.

A Service Instruction (SI-1305C) was issued for the 10-5009 and 10-5062 that calls for the replacement of the main jet with a new nozzle to provide better fuel atomization. You want this mod if you use one of these carbs. It helps equalize the fuel distribution between cylinders to keep some from running lean and hot. If the carb number is 10-5009N or 10-5062N, it already has the mod. If you need to ream that nozzle to get better cooling, try reaming it to .096. If that is not enough, try .099.

In terms of other carbs for your engine, I believe that the 10-5135 is the 5009 with the new nozzle installed at the factory. The 10-5217 is the latest version of this series and has replaced the 10-5135. These are good carbs and include later engineering than the -32 models which were designed in the 50s. I would give the carb you have a try for your project.

Bob

So it seems to me that you have a good model carb with the desireable "pepperbox" nozzle - might need to be reamed a little if you're still hot on climb-out.
 
I did buy a new nozzle, and mechanic did ream it out some. I think it's worth trying a bit more. I think the one he took out was a 'pepperbox' as well.. so I'll be able to go back to the current one if the next size is too much.

Too many projects on the list. :)

JP
 
All is well on the TCOW. I'm amazed at how much cooler it runs with the prop pitched way down flat. I'm probably a little flatter than I SHOULD be for wheels.. with the 31s on there now. Ski season is right around the corner. Back row is in the high 300s now.. fronts around 300. I need to tweak baffling a bit still.

The 1600 foot runway with obstacles at the house is done. Need to seed in the spring.

I got a cheapie manometer. It confirmed my guess. I got about 2.5" water column in a climb. Best I saw was about 4.0 inches in a moderate decent.

SO.. I'll be going bigger on the seaplane lip. I bought the floats for it, so getting the cooling as good as I can is called for. A few tweaks left before winter, but I'm really happy where I've ended up.

Jason
 
Was that the major change - repitching the prop?

Did the new nozzle seem to make any difference?
 
Was that the major change - repitching the prop?

Did the new nozzle seem to make any difference?

Well Fall arrived when I repitched the prop. So cooler ambient. I went from way coarse pitch ( I went to Ohio and Indiana and back) to real fine pitch.
Also.. I changed the center hub on the wirlwind.. It's an 80" prop now instead of an 82"

The nozzle did make a difference, but I was still to hot for my comfort (425 in long sustained climbs.. summer temps)

The 35 dollar manometer and a few lines confirmed that I'm not getting the airflow that's optimal. I'll tweak the seaplane lip, see how big a difference it makes.

JP
 
I’d tighten up the baffles where I showed you at the bowman fly in first. Then seaplane lip. Do one change at a time so you know what effects what


Sent from my iPhone using Tapatalk
 
I do need to do that side piece. It's soft for sure. Getting to be to cold to mess with that stuff! I think it's due in the hangar once more before winter. New intercom needs to go in. The cooling stuff is going to have to be sorted well for float season.
 
I had a similar problem with my -14 and experimented with different lip sizes. Starting with a 1“ then 2” then 4” at the end, our conclusions yielded very small gains based on the lip size at the end of the day. Our largest gains came from adding the super cub style louvers to the lower cowl, which you already have.

Next was creating a flap using duck tape on the top of the baffling so when air passed into the cowl it couldn’t escape between the top cowl and the baffling, thus forcing it thru the cylinder fins. Cheap and fast way to check you baffling seal.

Next we were going to try ramps for the front cylinders and enlarging the lower cowl opening/lip combo, we didn’t make it that far though. We discovered the ring probe vs bayonet probes/ gauge combo lead to false readings during certain temperature ranges. Thus why sometimes the gauge was accurate sometime and other times wasn’t.

Your mileage may vary but that’s what we figured out.


Sent from my iPad using SuperCub.Org
 
Lycoming has fuel burn charts out, I found them when working on my plane, If I remember correctly 2700 RPM was over 14 GPH, I will try to find a link when I get a chance. I mentioned earlier that the pepperbox jet could be a problem. Each motor will be a bit different but I have seen one with a polished one pice venturi that required a number 29 drill bit to make it flow properly. I will get on the soapbox for a bit and reminded everyone that just because your buddy/CC/Backcountry or anyone else makes or changes a part does not mean it is right!!!! Get the instrumentation for you engine to tell what is going on. This post is a great example how proper gauges can save your motor. Just sending the carb out to be rebuilt/bench flowed will not work because every engine/application/cowling is different.
DENNY
 
On another note, Props make a huge difference on CHT'S. Change the pitch on a Borer 3 degrees and you can see a 20 degree CHT temp change.
DENNY
 
On another note, Props make a huge difference on CHT'S. Change the pitch on a Borer 3 degrees and you can see a 20 degree CHT temp change.
DENNY

100%. It’s about the power required in this situation. All other things being equal, coarser pitch requires more HP to spin at the same RPM. Producing HP generates heat.

If you have efficient cooling you can get away with higher “continuous” power production than if you have poor cooling.
 
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