MA-4-5 carb question

[bobby]

I have an overhauled O-360-A1A for my RV-8 and had installed a Rotec TBI. I have not flown yet and decided to go with a carb instead of the TBI. My installation is plumbed for the fuel inlet on the right side (as sitting in the plane). I just received an overhauled MA-4-5 part number 10-3878 carb. That is the one recommended by the mechanic who did the overhaul on the engine.

The carb came with the fuel inlet on the left side (as sitting in the plane). Can it be switched to the right side? It looks symmetrical. I haven't found a manual on line yet but from what I have found it looks like there is a filter screen at the inlet.

Thanks,

[Pat Hatch]

Bob,

I'm not sure about changing the fuel inlet to the right side, but I do think you might have the wrong carb for your airplane. The correct carb is p/n 10-4164-1. Your carb can be modified to a p/n 3878M with a kit that will make it the equivalent of the 10-4164-1 (basically a jet change). You also might want to check to see if you have the correct floats, p/n 30-862. Both these mods are pretty simple to accomplish. I would call a carb shop and ask them about these upgrades and whether the fuel inlet can be changed.

I had the older carb on my RV-6 with an O-360-A1A engine, and found that I was getting a slight stumble on climb out. After the mod, no more stumble. I also had the float kit done while it was in the shop.

[GalinHdz]

Originally Posted by Pat Hatch

Bob,

I'm not sure about changing the fuel inlet to the right side, but I do think you might have the wrong carb for your airplane. The correct carb is p/n 10-4164-1. Your carb can be modified to a p/n 3878M with a kit that will make it the equivalent of the 10-4164-1 (basically a jet change). You also might want to check to see if you have the correct floats, p/n 30-862. Both these mods are pretty simple to accomplish. I would call a carb shop and ask them about these upgrades and whether the fuel inlet can be changed.

I had the older carb on my RV-6 with an O-360-A1A engine, and found that I was getting a slight stumble on climb out. After the mod, no more stumble. I also had the float kit done while it was in the shop.

Where did you get the mod kit from?

[bobby]

Thanks for the info. I just got the carb. Maybe I could exchange it for the other model. But the mechanic was very specific. He said the 10-3878 is the preferred model. He said the 10-4164-1 will work but the 10-3878 is the better one for this engine. The engine is a narrow deck but it doesn't seem that could make a difference. Are there engines where the 10-3878 is the better choice or is the 10-4161-1 the better choice for all the O-360-A1A engines?

[az_gila]

Originally Posted by bobby

Thanks for the info. I just got the carb. Maybe I could exchange it for the other model. But the mechanic was very specific. He said the 10-3878 is the preferred model. He said the 10-4164-1 will work but the 10-3878 is the better one for this engine. The engine is a narrow deck but it doesn't seem that could make a difference. Are there engines where the 10-3878 is the better choice or is the 10-4161-1 the better choice for all the O-360-A1A engines?

The Kelly approved carb. chart lists both as being applicable for a O-360-A1A

http://www.kellyaerospace.com/fuel_c...ebler_Carb.pdf

For a certified aircraft the specific TCDS will specify which carb. must be used.

[Pat Hatch]

Originally Posted by GalinHdz

Where did you get the mod kit from?

I got mine done at AeroSport Power several years ago. Not sure what's going on now that Bart LaLonde and Sue Gregor have left.

[Pat Hatch]

Originally Posted by bobby

Thanks for the info. I just got the carb. Maybe I could exchange it for the other model. But the mechanic was very specific. He said the 10-3878 is the preferred model. He said the 10-4164-1 will work but the 10-3878 is the better one for this engine. The engine is a narrow deck but it doesn't seem that could make a difference. Are there engines where the 10-3878 is the better choice or is the 10-4161-1 the better choice for all the O-360-A1A engines?

I think you will find if you research it that it is a function of the performance of the airplane as well. I know that the original "M" mod came about because the Mooneys were having trouble with the 10-3878 carb due to the jetting in the economizer valve relative to the Mooney's higher speeds. Do a VAF search on the 10-3878 carb and I think you'll find more information on this issue.

Went back and found the thread that should help you: http://www.vansairforce.com/communit...t=10-3878+carb

[bobby]

Thanks, that thread helped. It seems some but not all 10-3878 models have issues but perhaps none of the 10-4164-1 do. The guy from Canada never replied if his had the "M" designation unless I missed it. I'm thinking I'll exchange it for the 10-4164-1. It will only cost some shipping now instead of parts and work later.

I did get an answer on changing the fuel inlet side and it is something that can be done. According to Marvel Schebler it doesn't make any difference functionally but could not be done on a certified aircraft. We don't have to worry about that here.

[Larco]

Back in the early 1990s Vans engines came with the 10-3878. I had one, it was to lean so I and many others did what we called the mooney mod. I believe sometime in the middle-late 1990s Vans started to supply engines with the 10-4164-1 which seemed to solve the lean problem. Larry

[bobby]

It looks like a problem with switching the fuel inlet is clearance with the throttle cable. I have a friends core 10-4164-1 on my engine to see how things fit and there might be less than a half inch, maybe a quarter inch, clearance. I'll need to check if that is acceptable but is seems a little close.

I ordered the 10-4164-1 and will send back the 10-3878. Thanks everyone for the heads up on this.