View Full Version : 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
T18
Lancelot37
10th Aug 2019, 19:19
Can you ask the manufacturer?
Well yes but it’s Saturday and a they are closed, I’m looking for a heads up from someone like Cockney Steve.
T18
NutLoose
10th Aug 2019, 22:36
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_Guidance_Library/rgMakeModel.nsf/0/6da1a9f45289fbd48525670e0050b3d8/$FILE/E-229.pdf
https://msacarbs.com/technical-data/engine-eligibility/
Hi Nutloose
It’s 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.
I’m surprised that it hasn’t been spotted before.
The a/c was built in 1970 as the demonstrator for the parts manufacturer “Thorp”
Thank you for the advice I will call N/M tomorrow, I note that Airpart may be an option although I won’t be exchanging like for like. The MA4 is for an O320 so may be more desirable.
Regards
T18
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.
Thanks Nae
It’s not possible to reject, replacement on order.
T18
That should have been re-jet....
would it be possible to replace the cylinders with O320 ones?
I’m in conversation with Nicholson McLaren at the moment, it’s certainly more involved-complicated than I f
Hi Nae
Thanks again for the heads-up, that was very useful, it seems I may be able to have the original studs removed and new ones fitted so all I need now is a carb.
T18