Carburetor STC

[C.J.]

On 8/19/2023 at 10:04 AM, Greg Ellis said:

@C.J. I am getting 19 GPH on takeoff with the stock richer carburetor. There is no mention in my logs about a jet change. I do not have the power flow.

@Greg Ellis Just sharing some info from my conversation today with Marvel Schebler. Do with it what you will, I am not an A&P.

They said that the upper & lower specs for the 10-4164-1 are 100.5 PPH (16.75 GPH) at full throttle and 4.8 PPH (0.8 GPH) at idle. 

I spoke with Power Flow as well & they said that when I do get my fuel flow installed to do several flights and adjust the K Factor as necessary.

For anyone reading this who is Power Flow equipped they provided me with an Engine “Richness” Test for Constant Speed Propeller aircraft to determine if my engine is rich enough or not. So if you haven't done this already and are interested just check the attached the PDF file

carb rich test constant speed.pdf

[Greg Ellis]

10 hours ago, C.J. said:

@Greg Ellis Just sharing some info from my conversation today with Marvel Schebler. Do with it what you will, I am not an A&P.

They said that the upper & lower specs for the 10-4164-1 are 100.5 PPH (16.75 GPH) at full throttle and 4.8 PPH (0.8 GPH) at idle. 

I spoke with Power Flow as well & they said that when I do get my fuel flow installed to do several flights and adjust the K Factor as necessary.

For anyone reading this who is Power Flow equipped they provided me with an Engine “Richness” Test for Constant Speed Propeller aircraft to determine if my engine is rich enough or not. So if you haven't done this already and are interested just check the attached the PDF file

carb rich test constant speed.pdf 15.78 kB · 1 download

Interesting.  I looked at my EDM 900 downloads and it varies but it ranges anywhere from just under 19 gph to just over 19 gph on my flights.  I will have to double check everything.

[DXB]

On 8/19/2023 at 8:39 PM, C.J. said:

My C already had Power Flow installed but I'm curious what were the after PF CHTs versus the before? 

~20 degrees hotter on #2 and 4 at WOT in climb. On a hot day this can mean struggling to keep them under 440 in clumb.  I generally try to get up to 120mph immediately upon takeoff before pitching up too much - this helps a lot

[C.J.]

1 hour ago, Greg Ellis said:

Interesting.  I looked at my EDM 900 downloads and it varies but it ranges anywhere from just under 19 gph to just over 19 gph on my flights.  I will have to double check everything.

@Greg Ellis  Your FF numbers may very well be correct. According to Power Flow even two individual carburetors, a single serial number apart, can have very different fuel flows at WOT & idle. So if your FF numbers are generally in synch with what you crosscheck with actual fuel burned upon refueling, I'd guess there's not an issue if that's your delta versus the WOT spec.

[C.J.]

1 hour ago, DXB said:

~20 degrees hotter on #2 and 4 at WOT in climb. On a hot day this can mean struggling to keep them under 440 in clumb.  I generally try to get up to 120mph immediately upon takeoff before pitching up too much - this helps a lot

@DXB Food for thought in case you haven't already done this - After I had every seam, gap & hole on the doghouse sealed with RTV there was a 30*F decrease of CHT (390 versus 420) as well as oil temp (190 versus 200). I still transition to a 120 mph climb at 500' agl like I did before sealing the gaps, but now I'm always below 400*F even on the hottest summer day.

[jetdriven]

21 hours ago, C.J. said:

@Greg Ellis Just sharing some info from my conversation today with Marvel Schebler. Do with it what you will, I am not an A&P.

They said that the upper & lower specs for the 10-4164-1 are 100.5 PPH (16.75 GPH) at full throttle and 4.8 PPH (0.8 GPH) at idle. 

I spoke with Power Flow as well & they said that when I do get my fuel flow installed to do several flights and adjust the K Factor as necessary.

For anyone reading this who is Power Flow equipped they provided me with an Engine “Richness” Test for Constant Speed Propeller aircraft to determine if my engine is rich enough or not. So if you haven't done this already and are interested just check the attached the PDF file

carb rich test constant speed.pdf 15.78 kB · 7 downloads

We have a client with an 0320 on a cardinal with a power flow. We installed a JPI830 and right away he noticed how hot that thing runs all the time. Especially after takeoff. We noted that his EGT's are  1525° full throttle static on the ground. And in fact, pulling the mixture back even a little bit caused the EGT's to came down so it had far insufficient fuel flow. It took three go around taking the carburetor off and sending it back to the place to have it reamed out or jets swapped out to get more fuel flow. Finally after the third time his EGT's are 1285 on takeoff and it's about 16 gallons per hour for this 150 hp engine.

[C.J.]

@jetdriven  Who was reaming the carb & swapping jets, Power Flow, Marvel or was it D&G ? 

[jetdriven]

Yes. D&g

[DXB]

On 8/22/2023 at 8:37 AM, C.J. said:

@DXB Food for thought in case you haven't already done this - After I had every seam, gap & hole on the doghouse sealed with RTV there was a 30*F decrease of CHT (390 versus 420) as well as oil temp (190 versus 200). I still transition to a 120 mph climb at 500' agl like I did before sealing the gaps, but now I'm always below 400*F even on the hottest summer day.

Perfectly legit suggestion - unfortunately I have done this obsessively and much more over years without achieving your results.  

[Shadrach]

On 8/5/2023 at 3:18 PM, ShuRugal said:

Fair enough. Is that small increase enough to change the cylinder temperature enough to warrant a richer charge?

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My experience with the C,D and G models is that take off and climb CHTs have minimal margin on at least one cylinder or more.  I would not do anything to reduce that margin.  Better scavenging increases the cylinder's volumetric efficiency. It will take in more air and make more power. How much I don't know.  Anecdotally, back when I used to rent C172s, we had a 67 H model with an O300 (145hp) and power flow exhaust with a big ugly megaphone aft of the collector. It would climb with the O320 (160hp) birds no problem.  I preferred the power flowed, little continental six to the Lycoming fours by a large margin.

[Shadrach]

On 8/22/2023 at 8:19 AM, C.J. said:

@Greg Ellis  Your FF numbers may very well be correct. According to Power Flow even two individual carburetors, a single serial number apart, can have very different fuel flows at WOT & idle. So if your FF numbers are generally in synch with what you crosscheck with actual fuel burned upon refueling, I'd guess there's not an issue if that's your delta versus the WOT spec.

Whether "correct" or not, they are preferable to the take off FF I have seen on other C models. 

[C.J.]

7 hours ago, Shadrach said:

Whether "correct" or not, they are preferable to the take off FF I have seen on other C models. 

Should have used the word "accurate", but I get your point. With any luck I'll have takeoff fuel flow numbers for my C model by the end of September. 

[Shadrach]

On 8/22/2023 at 6:05 PM, jetdriven said:

 it's about 16 gallons per hour for this 150 hp engine.

And that's for an O320.

I know of several O360s with full rich, take off fuel flows in the same 16GPH range and EGTs in the mid to high 1400s. Predictably, CHTs are high.  Holding CHTs under 450 can be a challenge never mind 400.  I've mentioned it here before and it prompts a steady chorus of "raw EGT numbers don't matter"...  

 

[C.J.]

On 8/19/2023 at 5:16 PM, kortopates said:

The carb would have been OH at time of last engine OH. That would give you the age of the carb.


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@kortopates   Well, given there was no specific logbook entry of the carb receiving an overhaul at the same time the engine was overhauled I did some detective work. 1) A quick email to and very fast response from Lycoming confirmed my carb's s/n was the same one installed when they manufactured the engine in November 1978 and 2) a 5-minute phone call to the mechanic who field overhauled the engine in 2020 confirmed he did not get the carb overhauled due excessive/indefinite delays from D&G, with not even core exchanges being possible. This was back when the Covid19 crisis was emerging. So bottom line is my 45-year-old carburetor was shipped to D&G with an expected 2 week return and given they'll have tested it I'll know what my 10-4164-1 full throttle fuel flow is.

Edited August 27, 2023 by C.J.
corrected age of carburetor

[philiplane]

On 8/5/2023 at 2:20 PM, C.J. said:

Does anybody know the STC number for the modification that increases the takeoff fuel flow for a Marvel Schebler MA-4-5 carb?  Given I have a Power Flow exhaust I thought it would be a good idea to have the STC mod done. Thoughts??

 target max power fuel flow for a normally aspirated engine is .09 gallons per HP. So .09 x 180hp=16.2 GPH.

This should give 1280-1380 or so EGTs. The CHT's will be determined by how well your cooling system works. People mistakenly try to lower high CHT's with excess fuel, which is a bad idea overall. Excess fuel reduces HP, reducing your climb rate, and makes a mess of the inside of the engine. 

Proper max power fuel flow should produce EGT's that are about 200-250 degrees rich of peak.

Edited August 26, 2023 by philiplane

[C.J.]

5 minutes ago, philiplane said:

 target max power fuel flow for a normally aspirated engine is .09 gallons per HP. So .09 x 180hp=16.2 GPH.

@philiplane 

I already had a conversation with Marvel Schebler on 21 August. The upper & lower specs for the 10-4164-1 are 100.5 PPH (16.75 GPH) at full throttle and 4.8 PPH (0.8 GPH) at idle.  

[C.J.]

12 hours ago, philiplane said:

This should give 1300-1400 or so EGTs. The CHT's will be determined by how well your cooling system works. People mistakenly try to lower high CHT's with excess fuel, which is a bad idea overall. Excess fuel reduces HP, reducing your climb rate, and makes a mess of the inside of the engine. 

Proper max power fuel flow should produce EGT's that are about 200-250 degrees rich of peak.

@philiplane Thanks for the additional info in your edit. Cooling is very good at 390*F @T/O power on the hottest of days. All I've done since starting this thread maintenance-wise is to send the carb to D&G for overhaul. It's never been done in 45 years believe it or not. Never really had any issues with the carb though.

[Hank]

2 hours ago, C.J. said:

@philiplane 

I already had a conversation with Marvel Schebler on 21 August. The upper & lower specs for the 10-4164-1 are 100.5 PPH (16.75 GPH) at full throttle and 4.8 PPH (0.8 GPH) at idle.  

That doesn't match the Performance Tables for my 1970 C, you need more fuel.

[hammdo]

My 66 is 16.75 on the fuel flow and 1250° to 1275° EGT ( CHTs 390° to 395°) on takeoff without the power flow exhaust. I’m guessing you’ll need the STC upgrade for more flow than that…

-Don

[C.J.]

2 hours ago, Hank said:

That doesn't match the Performance Tables for my 1970 C, you need more fuel.

@Hank In 1965 Mooney didn't include a Sea Level, 59*F page in the POH. The first "cruise & range" data in my POH is at 2500 ft, STD Atmosphere. Those fuel flow figures were the specification for the 10-4164-1 carb I got directly from a conversation with Marvel Schebler. I'm not currently equipped with fuel flow, but by the end of September that will change and I will also have an overhauled carburetor from D&G too. Right now I'm taking it one (or two) steps at a time so we'll see what the numbers are then and decide if anything more needs to be done. This summer's CHTs were no greater than 390*F at takeoff & during climb so I'm thinking I'm OK. 

 

 

[Hank]

@C.J., here's my 2500 msl page. Note the fuel flow on it, too. Make sure Marvel Schleber gives you the higher fuel flow carb that's on the Mooney list. At 27"/2600, yours is 14.4 gph, mine is 16.5 gph. Wonder why the change?

[C.J.]

1 hour ago, hammdo said:

My 66 is 16.75 on the fuel flow and 1250° to 1275° EGT ( CHTs 390° to 395°) on takeoff without the power flow exhaust. I’m guessing you’ll need the STC upgrade for more flow than that…

-Don

@hammdo  With exception of fuel flow, which I'M not currently equipped with, your numbers are near identical to mine with Power Flow.

[C.J.]

7 minutes ago, Hank said:

@C.J., here's my 2500 msl page. Note the fuel flow on it, too. Make sure Marvel Schleber gives you the higher fuel flow carb that's on the Mooney list. At 27"/2600, yours is 14.4 gph, mine is 16.5 gph. Wonder why the change?

@Hank   My guess is that in 1965, Mooney chose the MA-4-5, 10-3878 version which had a lower T/O fuel flow. By 1970 Mooney smartened up and equipped with the higher fuel flow 10-4164-1 version to help with high CHTs. My 65C has the higher fuel flow version most likely because the engine I have was built new in 1978 and replaced the original engine from 1965. 

[hammdo]

20 minutes ago, C.J. said:

@hammdo  With exception of fuel flow, which I'M not currently equipped with, your numbers are near identical to mine with Power Flow.

Interesting, I’m in Texas and that is what I see with 100°+ temps. If I’m near max load, CHTs are 400°+ before I get to cruise climb…

-Don

[C.J.]

54 minutes ago, Hank said:

@C.J., here's my 2500 msl page. Note the fuel flow on it, too. Make sure Marvel Schleber gives you the higher fuel flow carb that's on the Mooney list. At 27"/2600, yours is 14.4 gph, mine is 16.5 gph. Wonder why the change?

 

@Hank Also when comparing your 1970's #s to my 1965 #s going with apples to apples, for the same weight of 2200 lbs your figures for less the 75% power are at lean mixture while mine are at best power mixture.