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  #21  
Old 03-28-2016, 03:18 PM
sblack sblack is offline
 
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Location: Montreal
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Default

I would try to get more data to see if it is always the #3 or if it is just random. Do you have an engine monitor that can record?
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  #22  
Old 03-28-2016, 04:04 PM
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acam37 acam37 is offline
 
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Location: Lufkin Tx
Posts: 689
Default Engine monitor

Yes Scott, I have that capability.
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  #23  
Old 03-29-2016, 09:01 AM
Monkey Monkey is offline
 
Join Date: Jun 2006
Location: Roanoke, Texas
Posts: 76
Default Bad Plug

I bet it's a bad plug. High EGT is one plug not firing. The 'bump' is when it starts to fire and then the EGT drops to normal.
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  #24  
Old 03-29-2016, 10:06 AM
mahlon_r mahlon_r is offline
 
Join Date: Jan 2005
Posts: 1,025
Default Mod kit is in SL 1305C from Lycoming

Quote:
Originally Posted by acam37 View Post
So what I am hearing is that I might be having a fuel/air distribution problem that is causing the intermittent stumble? It makes sense. Does anyone have the part numbers I need to change the jet mentioned above?
LW-13761 Carburetor Modification Kit consists of the following parts:
(1)47-828 Nozzle Assembly
(1)16-222 Nozzle Lock Gasket
(1)16-A107 Power Jet Gasket
(1)16-B75 Throttle Body to Bowl Gasket
(4)78-A110 Throttle Body to Bowl Screw Washer
After modification has been accomplished, stamp the carburetor nameplate with the suffix "N"
after the part number 10-5009 or 10-5062 which will then appear as 10-5009-N or 10-5062-N which
is equivalent to current production 10-5135 carburetor.
NOTE: Revision "C" updates Models Affected and adds paragraph after Note.
18078 - This number for Avco Lycoming reference only.
Page 2
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  #25  
Old 03-29-2016, 12:07 PM
matt wing matt wing is offline
 
Join Date: Mar 2016
Location: Cincinnati, Ohio
Posts: 2
Default O-320E2G stumble

this is very common in the Grumman AA5 series - so common it's been referred to as the "Grumman stumble". on a lot of the 4 place 0320 Grumman planes this happens, usually as power is pulled back or a mixture change. On my plane it only would happen once per flight but it was very predictable. My IA who specializes in the Grumman line knew immediately what I was talking about when I brought it up. The fix is to change the jet nozzle to a pepperbox design (many small holes instead of 1 large one).

I had my carb overhauled by Lycon in California to bring it up to current specs and have not had a single stumble since.

here's a snippet from the Grumman Gang Archives describing what was done....

"Still, the 10-5009 and 10-5135
was the approved carburetors that you could use on the O-320-E2G engine
until the 10-5217 was approved in the early 2000's. It incorporates all the
mods that can be done to the 5009 including the "Pepperbox Nozzle" which
helps a lot. If your 5009 has that it will have an "N" stamped on the data
plate (and possibly with an "M" denoting a metal float & a "V" denoting the
one piece venture)you have an updated carburetor commonly called a 10-5009N."

I believe mine was brought up to a 10-5217 configuration. Hope this helps!
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  #26  
Old 03-29-2016, 12:35 PM
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acam37 acam37 is offline
 
Join Date: Aug 2012
Location: Lufkin Tx
Posts: 689
Default

So, Im not crazy after all. Yes, this engine did come out of a Grumman and the carb does not have the pepper box nozzle. Im glad to hear that my stumble description has happened to other people and there is a fix. I'm going to upgrade my carb andwill post the results.
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  #27  
Old 03-29-2016, 08:58 PM
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The Wizzard The Wizzard is offline
 
Join Date: Nov 2009
Location: Cincinnati, Ohio
Posts: 149
Default H20

No gascolator, water in the tanks or some kind of contamination. The engine drinks it, the level goes down, mother nature puts more water in the tank, engine drinks it, level goes down, mother nature replaces it, engine drinks it..............got it!
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  #28  
Old 03-30-2016, 11:58 AM
BD4Guy BD4Guy is offline
 
Join Date: Sep 2007
Location: Los Angeles CA
Posts: 25
Default

While we have the ear of Mahlon, is a pepper box nozzle available for the MA4-5 on a O-360?

Thanks
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  #29  
Old 04-02-2016, 08:35 AM
mahlon_r mahlon_r is offline
 
Join Date: Jan 2005
Posts: 1,025
Default

The Fuel distribution improvement kit for the10-3878 carb, is called the -m kit. the M would be a suffix to the model number and then it would be a 10-3878-M.
The 10-4164-1 and the 10-5193 carbs, used on the 360's already incorporate that mod but don't have the -m suffix.
Good Luck,
Mahlon
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  #30  
Old 04-02-2016, 12:25 PM
Rusty Ellison Rusty Ellison is offline
 
Join Date: Jan 2016
Location: Macomb Michigan
Posts: 39
Default Engine Stumble

I appreciate the post, I too have experienced the same situation with my 0320 in it stumbling at various times. Sounds like this pepperbox fit might be the answer. My A & P was also leaning towards a carb situation. Interesting hearing of the Gruman stumble also.
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