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Carburetor - too rich

Old 10th Aug 2019, 14:07
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T18
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Carburetor - too rich

Hi Guys
I have been having an ongoing problem with rich mixture in my Lycoming O290d2, after trying various fixes my engineer has discovered that an MA4SPA has been fitted instead of of an MA3SPA, my question is can my existing carb be re-jetted to produce less fuel or is it a case of replacement?
Thanks in advance
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Old 10th Aug 2019, 19:19
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Can you ask the manufacturer?
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Old 10th Aug 2019, 22:24
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Well yes but itís Saturday and a they are closed, Iím looking for a heads up from someone like Cockney Steve.

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Old 10th Aug 2019, 22:36
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Your problem as I see it is it does not comply with the current type data certificate, which the engine is approved under, see link, I would try phoning the likes of Nicolson McLaren and have a chat, they may be able to do an exchange etc, incidentally they also tend to fit a different manufacturers carb these days that gets rid of several inspections like the float bowl coming loose etc. Have you contacted whoever overhauled it as I am assuming they were responsible for the mix up.

http://rgl.faa.gov/Regulatory_and_Gu...FILE/E-229.pdf

https://msacarbs.com/technical-data/engine-eligibility/

Last edited by NutLoose; 10th Aug 2019 at 22:50.
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Old 11th Aug 2019, 09:08
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T18
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Hi Nutloose

Itís an LAA type and certainly the wrong carb fitted, Nicholson McLaren overhauled the carb around 50 hours ago, the engine has recently had a top end overhaul and the rich mix has become more pronounced.
Iím surprised that it hasnít been spotted before.
The a/c was built in 1970 as the demonstrator for the parts manufacturer ďThorpĒ
Thank you for the advice I will call N/M tomorrow, I note that Airpart may be an option although I wonít be exchanging like for like. The MA4 is for an O320 so may be more desirable.
Regards
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Old 11th Aug 2019, 22:22
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The MA3SPA and MA4SPA carburettors have different mounting flanges so your sump is also incorrect. The studs are closer together on the MA3SPA, they are also 1/4 diameter rather than 5/16.
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Old 13th Aug 2019, 08:31
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Thanks Nae
Itís not possible to reject, replacement on order.
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Old 13th Aug 2019, 17:59
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That should have been re-jet....
would it be possible to replace the cylinders with O320 ones?
Iím in conversation with Nicholson McLaren at the moment, itís certainly more involved-complicated than I f
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