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  #31  
Old 04-12-2021, 08:34 AM
00Dan 00Dan is offline
 
Join Date: Nov 2016
Location: Atlanta, GA
Posts: 183
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Quote:
Originally Posted by lr172 View Post
The standard is 200 ROP when full rich, WOT at sea level. It is nice to have that margin for detonation prevention on Take off. You should be more worried about WOT SL than at cruise, as that is where you will have the most problems from being lean. Did you by chance measure the float height while the carb was apart? Fuel flow is determined mostly by jet size and fuel height in the bowl for any given airflow rate. A float that is slightly low will cause lean running. Even 64ths and 32nds can make a meaningful difference. Always measure float height when the carb is apart.

Larry
I did not measure the float height. The carb guru on the airport who did the bushing for me mentioned that he did not adjust it as it was unnecessary.

I can measure it next time I have the carb open since it looks like Ill have to go in again anyway. I will note my carb has the brass float, if that makes any difference.
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  #32  
Old 04-12-2021, 11:40 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,324
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Quote:
Originally Posted by 00Dan View Post
I did not measure the float height. The carb guru on the airport who did the bushing for me mentioned that he did not adjust it as it was unnecessary.
If he is any good, he would have measured it before making that statement.
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  #33  
Old 04-12-2021, 08:36 PM
00Dan 00Dan is offline
 
Join Date: Nov 2016
Location: Atlanta, GA
Posts: 183
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Does anyone have experience with the nozzle PN 47-862 that MSA developed for the Carbon Cub with the Titan 340? Per SB-22, it is a drop in replacement for 47-773 jet that is standard in the 10-3678-32.

I'm waiting to hear back from MSA on the nominal flow rate. The Carbon Cub users report good results but I can only find qualitative reports. I wonder if the results will be applicable to the faster RVs.
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  #34  
Old 04-18-2021, 07:02 PM
00Dan 00Dan is offline
 
Join Date: Nov 2016
Location: Atlanta, GA
Posts: 183
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Quote:
Originally Posted by 00Dan View Post
Does anyone have experience with the nozzle PN 47-862 that MSA developed for the Carbon Cub with the Titan 340? Per SB-22, it is a drop in replacement for 47-773 jet that is standard in the 10-3678-32.

I'm waiting to hear back from MSA on the nominal flow rate. The Carbon Cub users report good results but I can only find qualitative reports. I wonder if the results will be applicable to the faster RVs.

Per MSA the 47-862 nozzle is the same flow rate as the 47-773. I ordered and received the 862 nozzle earlier this week, it measured to #36 ID (same as the 773).

I flew it today and performed some lean tests. At 2500 and WOT, #1 peaked first with full rich being approximately 110* from peak. At 8500 and WOT #2 peaked first approximately 250* from full rich.

My previous nozzle (47-828) had some aeration holes for atomization, and at 8500 showed approximately a 130* spread between richest and leanest cylinder. After I reamed it from #42 to #40, the spread was 170*. The new nozzle (47-862) had significantly more aeration holes from the factory and showed a spread of approximately 80*.

Further testing is needed but it seems the 47-862 nozzle has gotten me close to where I need to be, at the least. Ill also note I did measure my float height when I had the carb apart and found it to be at the nominal value of 7/32.
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