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0-360 Riser / adapter from carb to sump?

mechmike

Member
I've been a long time lurker and figured what better place to see if anyone has seen this before...

I didn't build or install this but I have an 0-360 C2E out a Mooney and it came with a MA-4-5 P/N 10-4164-1 attached.

It runs too rich and I aggressively lean it for smooth running in cruise. Strangely, when leaning it out at low idle the rpm raise is less than 50 as it dies, as it should be. It soots plugs, I only run mogas but they are not badly fouled.

I read about the Service bulletin SB258 for the tapered riser insert in the sump but it seems that is only an 0-320 issue. My combination has about a 1/4" lip all around (sump hole is larger than the carb outlet) and seemingly needs a tapered riser?

Does anyone have any thoughts on this? Engine seems a bit low on power. But nothing to compare it to.

I'll try to attach a photo taken through the #1 intake pipe. It looks at a round mirror that looks down at the shelf that the top of the carb creates.
Never mind seems I can't do that.

Thanks all.

Mike
 
Mike, I?m familiar with the lip of the carb being slightly smaller than the sump and creating a sharp corner/transition. It?s in the back of my mind to create a spacer/cone to make the transition a smooth one. Just a whim but I?m guessing it has nothing to do with your ?rich,? more so it?ll change your mixture distribution.
I added a thin (1/8? if I remember correctly) phenolic spacer to thermally isolate my carb from the hot sump. I recall finding the different circumferences of the carb and sump. I didn?t have the time to make an insert as described in the SB for the 320 and I couldn?t use a thicker spacer since I was utilizing the original studs and the airbox/cowling transition. I did taper the 1/8? spacer as much as possible to smooth the transition from carb to sump and did note an improvement/change in my fuel distribution via EGT?s being closer at full throttle and leaning. Not sure that it improved my mixture distribution in every realm, but lucked out in that It evened out more at full throttle.
 
MA4-5

There are three carbs for this engine & configuration your 10-4164-1 is known to run rich. I'm told the 10-3878 works better in the RV. If I may ask. How is your Float? Mo gas is very corrosive to old seals and floats? Just a thought.
RHill
 
I added a thin (1/8? if I remember correctly) phenolic spacer to thermally isolate my carb from the hot sump.
Dang! I thought I was the only genius who did that! LOL! The heat from the sump was causing the fuel in the carb bowl to boil on a hot day, so I added a 1/16" phenolic spacer for thermal isolation on my O-290-D2. I would have gone thicker but the studs weren't long enough. That fixed the heat problem but now I have a fuel distribution problem; On climbout, EGTs 3 and 4 get sky high and I have to back off the throttle to get them back down. In cruise, everything is nice and level. I still haven't figured out how to fix that. Maybe I'll look closer at the transition from carb to sump. Could that be it?
 
There are three carbs for this engine & configuration your 10-4164-1 is known to run rich. I'm told the 10-3878 works better in the RV. If I may ask. How is your Float? Mo gas is very corrosive to old seals and floats? Just a thought.
RHill

Not completely correct in my opinion.
The 10-4164 is richer than the 10-3878 yes.
If you are at sea level and have a CS prop....you need richer.
If you live high and have fixed pitch the leaner works.
If you are rich you can pull the red knob.
If you are lean....you can hurt your engine.
FYI I had the 10-3878 and had to drill the main jet to get richer bc I live at 500msl and have a CS prop.
 
Dang! I thought I was the only genius who did that! LOL! The heat from the sump was causing the fuel in the carb bowl to boil on a hot day, so I added a 1/16" phenolic spacer for thermal isolation on my O-290-D2. I would have gone thicker but the studs weren't long enough. That fixed the heat problem but now I have a fuel distribution problem; On climbout, EGTs 3 and 4 get sky high and I have to back off the throttle to get them back down. In cruise, everything is nice and level. I still haven't figured out how to fix that. Maybe I'll look closer at the transition from carb to sump. Could that be it?

So mine must also be 1/16? as you sent me the scrap phenolic I used! It did change my mixture distribution, but kinda a ?you get what you get.?
I used to have over 125* EGT spread at full throttle, carb heat did nothing but 3/4 throttle evened the RGT?s out nicely within 30-40* in cruise.
I did taper the Transition of the spacer best I could and it did change my EGT distribution. Full throttle and low RPM has a wide spread well over *125 but at cruise RPM and full throttle EGT?s are now 50-60* spread and I can run LOP. 3/4 throttle brings the EGT?s closer but not as close before.
 
Not completely correct in my opinion.
The 10-4164 is richer than the 10-3878 yes.
If you are at sea level and have a CS prop....you need richer.
If you live high and have fixed pitch the leaner works.
If you are rich you can pull the red knob.
If you are lean....you can hurt your engine.
FYI I had the 10-3878 and had to drill the main jet to get richer bc I live at 500msl and have a CS prop.

+1. FYI In 1995 the factory 360s came with the 3878 many of us had to do the Mooney mod (making it a 4164) or drill the jet to get rid of a lean miss during full throttle on take off at sea level due to the ram air. Some time after that the 360s started coming with a 4164 from the factory. Kay from Lycoming actually sent me a 4164 replacement because I flew out of a sea level airport. Yes, I did have to pull the red knob out further in cruise but that is what it's for. Worked wonderful. BTW the Mooney required a richer carb because it had ram air according to Lyc.
 
I used a die grinder to chamfer my carburetor out to the same diameter as mu sump inlet. I don't have enough headroom between my bottom cowling and air filter box to add a spacer. I was hoping this would help with my F/A distribution from cylinder to cylinder. I cant say it mad a huge difference, but I do think it helped some. There is no longer a fuel puddle sitting on this ledge.
 
So mine must also be 1/16? as you sent me the scrap phenolic I used!
Oh geez, I had forgotten! It's **** getting old. I'm glad it's working for you. I went flying today and at cruise, after leaning, my first three EGTs were within 5 deg of each other, except for #4 which was 25 deg hotter. I may need to drill more holes in my carburetor nozzle.
 
+1. FYI In 1995 the factory 360s came with the 3878 many of us had to do the Mooney mod (making it a 4164) or drill the jet to get rid of a lean miss during full throttle on take off at sea level due to the ram air. Some time after that the 360s started coming with a 4164 from the factory. Kay from Lycoming actually sent me a 4164 replacement because I flew out of a sea level airport. Yes, I did have to pull the red knob out further in cruise but that is what it's for. Worked wonderful. BTW the Mooney required a richer carb because it had ram air according to Lyc.

I have a 3878 on my O-360 RV7. Ran too lean. Put the Mooney mod kit in (one size larger nozzle and restrictor for the economizer cct) ,which made it equivalent to the 4164, and it runs great. The restrictor makes the carb run richer at WOT. Also put the new blue float in at the same time. The 3878's with the Mooney mod kit are supposed to be stamped with an M on the tag. No spacer or grinding done...just a gasket.
 
MA4-5

I just wanted to point out.There may be other issues going on. Porous Float comes to mind. Health of the mags/plugs another. OP has soot on plugs. Nice 50 rpm rise on shut down. Lack of power. Starting with the basics is always better then chasing issues down stream. A lot of guys run Mo Gas without issue,others have problems. My post was not about the carb model but more about Basics.My 66 M20C had a u shaped air box horn without a filter, The RV has a KN so air flow might play a role?
 
Good to hear others have noticed the lip.

Yes I'll get a blue float and new seals all around (from Spruce?) I only run non ethanol MoGas but still, it's been a long while since anyone has been in that carb.

I don't have extra room to lower the carb and do a large transition spacer so while I'm there I'll see about machining some kind of tapered cone like the 0-320 SB, or wrecking the core and beveling the top of the carb.

Thanks
Mike
 
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