180 horsepower carburetor help needed

[learaviator]

I was wondering if anyone who has a 180Hp conversion can tell me what carburetor part number they have on their engine. Should be a 10- something. I am questioning the carburetor on my plane. There is a article on Sac Sky Ranch about a engine problem, and in it they say the Avcon conversion, at least for a 172 requires a richer carburetor than what an O-360 normally calls for. My engine is definetely running lean at full rich, and I am hoping this is the problem. I have a 10-3878 and the article calls out a 10-4164 as a richer carburetor.

[canav8]

Wow, that is interesting. Being the devils advocate, Why would a different carb be necessary based on the aircraft installation with a prop on the front? Sorry I believe a lot of SAC Sky Ranch stuff but if there is an article covering this, I would have to say they got it wrong!
A carb that runs richer or leaner? Sorry, I would consider checking the indexing on the mixture control rod not put a different carb on there. Pull a TCDS on your engine and read what is required or check to see the AVCON installation as what carb is required if they got the STC with a different carb. Generally people wont go and just get a carb they had laying around and slap it on when they are making an STC, if you know what I mean.
Doug

[learaviator]

I am assuming that they are talking about a carb that either flows more air or has bigger main jets, I compared the parts breakdown for both part number carbs, and there are differences in the metering end of things. My STC is not an Avcon and no paperwork is available for my STC (KWAD) that would list the recommended carb, so I have no way of verifying what carb was intended for my particular aircraft. Sac Sky Ranch says that Avcon conversions require the use of a different carb than what a standard carb would be for a O-360-A1A. When I go to an old Precision catalog, they do list both carb PART NUMBERS as being elegible for my engine. The TC for the engine simply calls out a model number, MA-4-5, but their are multiple variations of that carb, hence the part number differences. I would think for example a low compression 180 hp would take a different carb than a high compression 180 hp engine. I was looking for some input as to someones particular part number on their carb on a 180 hp installation. Particularly someone who has a KWAD STC for 180 hp.

[GAHorn]

...Why would a different carb be necessary based on the aircraft installation with a prop on the front? ...

One explanation might be the individual aircraft induction system differences. A long S-shaped plenum would have greater resistance to flow than a straight-forward filter in front of an air-box. (Think of the differences between early/late 182's.) Consider the differences between an O-300 installed in a 170 with a rigid metal airbox, and a GO-300 installed in a 175 with a flexible plenum. Same engine displacement, similar aircraft configurations, but very different operational RPM and induction systems.

[learaviator]

You are right George, they do mention carb air box design differences as a reason for the carb differences. I just finished reading the whole article.

[tweiss]

Learaviator,

May not help you with your (KWAD) STC, but on my Avcon conversion with an O360-A1A, the carburetor description # is MA-4-5, and the part # is 10-4164-1.

By the way, the wing vent grommets you sent me have worked out great.

Thanks again.

Tom

[learaviator]

You are quite welcome, I am glad the grommets worked. That is the exact carburetor that Sac Sky Ranch said was needed, and I have the one that they say is the leaner running of the two. Thanks for the info!!