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  #11  
Old 02-24-2016, 03:08 PM
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Dbro172 Dbro172 is offline
 
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Research how to do a test to see if its running too lean.... for example fly 75% power at 8500' and then start tp lean - you should see a rise in EGTs of say at least 100-200 degrees before they start falling off on the lean side of peak. If you see little or no rise, or it starts falling off immediately, its probably too lean. I think you can do a 75% run up on the ground too, but it might not be as accurate (watch CHTs obviously on ground run).

If you do suspect it is jetted too lean; rather than experiment yourself, you can send the carb to Marvel Shebler where they can bench test / flow test to see if its getting adequate flow for your setup and they can modify the jetting accordingly..
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  #12  
Old 02-24-2016, 03:24 PM
PaulR PaulR is offline
 
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There are many different MA4SPA Carbs. The model number of it is on the tag. Most of them have different jets in them. I don't know where the B1A was used in the certified world but "most" of the carbs are too lean for our tightly cowled RV's. You'll find that a lot of discussion on here about drilling out the main jet slightly to get the needed 12-14 GPH needed at full throttle take off.
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  #13  
Old 02-24-2016, 03:29 PM
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Quote:
Originally Posted by vic syracuse View Post
My experience has been that the RV-9's will cool much better with a climb rate around 120 KTS. Even with a fixed pitch prop climb rates are usually around 900-1000 FPM. Climbing at VX for any length of time will cause high temps.

Vic
Without reading any of the other posts I am going to agree with Vic on this one. More than anything this can help greatly. With a fixed pitch prop you need to take what you can get and live with it. That means for climb you should consider what many might call a cruise climb. In my case I keep my climb speed around 115-117 mph unless some specific circumstance calls for something else. This keeps a good airflow across the cylinders. I would say start here. See what your temps do in climb at a speed somewhere in the 115-120 mph range.
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  #14  
Old 02-24-2016, 03:44 PM
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Quote:
Originally Posted by PaulR View Post
There are many different MA4SPA Carbs. The model number of it is on the tag. Most of them have different jets in them. I don't know where the B1A was used in the certified world but "most" of the carbs are too lean for our tightly cowled RV's. You'll find that a lot of discussion on here about drilling out the main jet slightly to get the needed 12-14 GPH needed at full throttle take off.
Everyone I know with a carbed RV has had to bore out the jet to reduce CHT, primarily at take-off.
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  #15  
Old 02-24-2016, 03:51 PM
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Quote:
Originally Posted by bluebrear View Post
Hi Steve,
I'm the builder/owner/pilot. My test pilot friend has flown the hours.
I can answer most of your questions.
1. Fuel flow has not been calibrated yet.
You need to know what this is. I would prioritize doing this as soon as possible. It will be key for you in the proper operation of your engine.
2. Mixture is full rich at climb out/cruise is leaned somewhat.
One other question I did not ask is what elevation you are flying out of. My home field is at 1350 ft MSL. At that altitude I cannot run full rich without issues that I choose not to deal with. If at sea level then full rich may be necessary. Anything higher than sea level lean it out and your engine will run better, and thank you for it.
3.Temp at Full Rich TO was 455 for #1, I'm not sure of exact changes ROP/LOP
Again similar answer as #2 above. I do not know of any instances except for when I have been actually at sea level or during starting that I run full rich.
4.Climb rate at Vx was 1800 fpm
5. Airspeed at high temp was 100 kts
100 kts is acceptable but perhaps you need more airflow over the cylinders.
6. Probes are in Lycoming wells, bayonet type.
7.To lower temp, lower ROC
8.At high temp: 1/455, 2/454, 3/442, 4/409 Cruise: 1/368, 2/345, 3/333, 4/331
Yes, I also would be concerned with these climb temps. Even if mine were to make it there (mine have never been that high)I would not allow them to remain there. Since they are all in the same relative range then I would say you need to get air flowing across them better. As for cruise temps those are respectable numbers for cruise for running Rich. You can get them cooler running LOP but with a new engine and plane I would not concern yourself about that now.
9. Unison; Yes
10. High temp report at full rich.
Any clues?
As I have mentioned above, I don't think running full rich is all that good for the engine. Especially at altitude. Try leaning out more in climb and keep your air flow up with airspeed on climb out. I don't recall if you stated this was a new engine. If so then running hard and hot on break in is not necessarily a bad thing. Although, I would admit running in the 450 deg range is a little hotter than I would want myself. Is this a new engine?
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  #16  
Old 02-24-2016, 07:00 PM
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Quote:
Originally Posted by bluebrear View Post
Hi Steve,
I'm the builder/owner/pilot. My test pilot friend has flown the hours.

4.Climb rate at Vx was 1800 fpm

5. Airspeed at high temp was 100 kts

8.At high temp: 1/455, 2/454, 3/442, 4/409 Cruise: 1/368, 2/345, 3/333, 4/331
My advice is to strike your test pilot smartly with a stick. Tell him to quit doing extended climbs at Vx. Vx is for clearing trees.

Then take the air dam off #1, and slap a piece of aluminum tape across the oil cooler.

Be happy.
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  #17  
Old 02-24-2016, 08:18 PM
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I agree with Dan. Lower the nose and climb at a higher airspeed.

You haven't calibrated fuel flow yet, but what are your EGT's reading at takeoff. As much as people will say eyndont matter, they can be an indication of running too lean at high power. My RV-6A with a 150HP O-320 was running 1450-1500 EGT's on takeoff and the CHT's quickly climbed above 400 and I even saw 450, even at a reasonably high airspeed. I drilled out the jet and verified I was hitting the full rich stop (I wasn't at first). Got the EGT's down to the low to mid 1300's and the CHT's can be kept under 400 in climb if I pull the power back a little. One more drill size to get them in the 1200's and I think I'll be good to go. The absolute EGT numbers are not always a clear indication, but they can help determine if you are running too lean, which will easily cause high CHT's. I'm ready to be flamed, as I have been in the past, but the numbers don't lie, at least in my experience. You are reading all 4 CHT's, so I assume you are reading all 4 EGT's as well. What were they att full power takeoff?
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  #18  
Old 02-24-2016, 08:32 PM
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N941WR N941WR is offline
 
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Count me in for agreeing with Dan regarding climb speeds.

After reaching 1,000' AGL, I typically cruise climb at 500 FPM which gets the speed up and you heading towards your destination at a good clip.
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  #19  
Old 02-24-2016, 08:34 PM
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Quote:
Originally Posted by Jesse View Post
I agree with Dan. Lower the nose and climb at a higher airspeed.
Ummmm, I am sure glad Dan agreed with my statements and gave his advice as he did. I guess I should have waited until after he said anything to post the same advice, then I would have been in agreement with him too! Although I guess the thing I did not suggest is striking the test pilot with a stick. So, I agree with Dan. Strike that guy with a stick!
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  #20  
Old 02-24-2016, 08:49 PM
krw5927 krw5927 is offline
 
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I agree with Steve and Bill and Jesse in agreeing with Dan
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