Lycoming IO-360 Fuel Nozzle torque and "A" position

[redbaron1982]

Hi guys,

I'm replacing the fuel nozzles in my M20J. I'm trying to follow Lycoming SI 1275C, which indicates to tighten to 60 in-lb and then until the A faces down.

On the other hand, if I read SSP 1776 (SERVICE TABLE OF LIMITS AND TORQUE VALUE RECOMMENDATIONS) it indicates max torque for the fuel nozzle (ref 914) 60 in-lb.

In my case, this is the follow that I've done:

• Tighten to 40 in-lb.
• Check the positions of the A, it was in the 9 o'clock position.
• Continue tightening to 60 in-lb and check the position of the A, it was exactly in the 12 o'clock position.
• I continue to 80 in-lb, check again the A and was in the 2 o'clock position. I really don't want to continue torquing until it's facing down, as most likely it will be well over 100 in-lb.

I will check today with the mechanic that is helping me with this, but what's your experience with this? I don't feel ok either under torquing, like to 30 in-lb or over torque to 120 in-lb or so.

At this point I prioritize being at 60 in-lb over the A position, as I understand the A position only affects the possibility of having some drops of fuel near the nozzle after shutdown.

Thanks!

[N201MKTurbo]

You can take an 1/8 npt tap and run it in a tiny bit.

[EricJ]

I've faced this dilemna as well, and just determined that not over-torquing is more important than proper position of the A.   Getting the A in a good spot is definitely beneficial, but not a real requirement.   Moving the injector to another cylinder where it may clock better is another option, or a light application of a tap as suggested above.

 

[redbaron1982]

25 minutes ago, EricJ said:

I've faced this dilemna as well, and just determined that not over-torquing is more important than proper position of the A.   Getting the A in a good spot is definitely beneficial, but not a real requirement.   Moving the injector to another cylinder where it may clock better is another option, or a light application of a tap as suggested above.

 

For the time being, I will follow the same path as you and monitor.

I really don't like at this point to tap the thread, as with the luck I'm having I will end up with burr in the cylinders and having bigger problems.

[Ragsf15e]

I have one of my injectors that does similar. We always do the best we can, but definitely don’t over torque it. The hole being down may dribble a little fuel once in a while, But that’s not the end of the world. We did make a sharpie line on the opposite flat from the A Because what the heck, you can’t see the A when it’s pointed straight down and it’s a tiny space so you can’t look under there!  The sharpie line on the opposite flat makes it easier to see how close you are. 

[N201MKTurbo]

I put a piece of masking tape around the 1/2 inch socket and draw lines on opposite flats. I mark one of the lines with an A. I rotate them till the non A line is up. You have to align the A line with the A on the injector when you put the socket on.

[PT20J]

You might try lubricating the threads with engine oil. See attached p177. Also, when torqueing into aluminum, turn the wrench slowly as aluminum has a tendency to gall which will cause you to reach the torque limit early.

MM-IO-360-N1A - 3-31-2016 (1).pdf

[Shadrach]

This is a recurring theme with injector installation.  In my opinion the position of the A is not that important as long as it falls somewhere between 3 and 9 o’clock. Chasing your tail to get it perfectly aligned at 6 o’clock is futile. I’ve never had to run a tap get them within correct Range of orientation and torque value, but it seems to me that’s the only option if you can’t.

this is an operation where it pays to be conservative at every step. Channel your inner finesse and be gentle.

[redbaron1982]

Thanks, guys. As these are new injectors (stock ones, not GAMIs) what I'm planning to do is run them as they are now, get the GAMI spread, and then see if I need to change any of the restrictors to have it under 0.5GPH.

Whenever I do that activity I will take out also the nozzle's body, clean the cylinder head thread, and use motor oil to lub the injector nozzle.

BTW: I did thread the nozzle bodies slowly, I'm always super gentle when threading in aluminum, don't want to cross-thread or strip the threads. Too many bad experiences in the past.

[Shadrach]

1 hour ago, redbaron1982 said:

Thanks, guys. As these are new injectors (stock ones, not GAMIs) what I'm planning to do is run them as they are now, get the GAMI spread, and then see if I need to change any of the restrictors to have it under 0.5GPH.

Whenever I do that activity I will take out also the nozzle's body, clean the cylinder head thread, and use motor oil to lub the injector nozzle.

BTW: I did thread the nozzle bodies slowly, I'm always super gentle when threading in aluminum, don't want to cross-thread or strip the threads. Too many bad experiences in the past.

I’ll be curious to know what your GAMI spread is. I’m betting it’s well under 0.5 

[Guest]

6 hours ago, N201MKTurbo said:

You can take an 1/8 npt tap and run it in a tiny bit.

What about dislodging the Helicoil?

[Guest]

6 hours ago, redbaron1982 said:

Hi guys,

I'm replacing the fuel nozzles in my M20J. I'm trying to follow Lycoming SI 1275C, which indicates to tighten to 60 in-lb and then until the A faces down.

On the other hand, if I read SSP 1776 (SERVICE TABLE OF LIMITS AND TORQUE VALUE RECOMMENDATIONS) it indicates max torque for the fuel nozzle (ref 914) 60 in-lb.

In my case, this is the follow that I've done:

• Tighten to 40 in-lb.
• Check the positions of the A, it was in the 9 o'clock position.
• Continue tightening to 60 in-lb and check the position of the A, it was exactly in the 12 o'clock position.
• I continue to 80 in-lb, check again the A and was in the 2 o'clock position. I really don't want to continue torquing until it's facing down, as most likely it will be well over 100 in-lb.

I will check today with the mechanic that is helping me with this, but what's your experience with this? I don't feel ok either under torquing, like to 30 in-lb or over torque to 120 in-lb or so.

At this point I prioritize being at 60 in-lb over the A position, as I understand the A position only affects the possibility of having some drops of fuel near the nozzle after shutdown.

Thanks!

You can play around with cylinder and nozzle locations to get closer to the correct torque and positioning.

[Shadrach]

1 hour ago, M20Doc said:

You can play around with cylinder and nozzle locations to get closer to the correct torque and positioning.

I’ve tried that several times with multiple engines and it’s always a game of whack-a- mole. One cylinder might be better but then another becomes the problem child. 
 

 

[N201MKTurbo]

29 minutes ago, M20Doc said:

What about dislodging the Helicoil?

I’ve never seen a helicoil in the injector port. I’ve never seen an NPT helicoil.

[A64Pilot]

Ref the Gami spread, who cares what it is, if the engine will run smoothly deep LOP?

[Fly Boomer]

37 minutes ago, A64Pilot said:

Ref the Gami spread, who cares what it is, if the engine will run smoothly deep LOP?

Maybe if it will NOT run LOP, it would be one possible explanation.

[PT20J]

5 hours ago, redbaron1982 said:

Thanks, guys. As these are new injectors (stock ones, not GAMIs) what I'm planning to do is run them as they are now, get the GAMI spread, and then see if I need to change any of the restrictors to have it under 0.5GPH.

Whenever I do that activity I will take out also the nozzle's body, clean the cylinder head thread, and use motor oil to lub the injector nozzle.

BTW: I did thread the nozzle bodies slowly, I'm always super gentle when threading in aluminum, don't want to cross-thread or strip the threads. Too many bad experiences in the past.

If you do decide to swap around nozzles between cylinders to improve balance, I'd keep the injector body and restrictor together and swap entire assemblies. When I was at the Precision Airmotive factory, Al Jesmer showed me how they don't actually measure flow on the nozzles but they do run each on the flow bench to make sure that the fuel streams out in a solid stream about the diameter of a #2 pencil lead. If not, they change restrictors until they get a combination that does.

Skip

[Shadrach]

2 hours ago, A64Pilot said:

Ref the Gami spread, who cares what it is, if the engine will run smoothly deep LOP?

With all new injectors, he’s going to want to verify which cylinder is richest (likely #2) and which is leanest (likely #3) so he can chose the correct cylinder EGT to use for ROP or LOP operations. Why not note the fuel flow change while leaning from one to the next? It’s not a lot of work.  Besides, the tighter the spread, the more effective the red knob is at generating the desired result. A well conforming engine is better for operations anywhere on the mixture spectrum.

[MikeOH]

@Shadrach

Curious why #2 would be more likely the richest?

[Shadrach]

20 minutes ago, MikeOH said:

@Shadrach

Curious why #2 would be more likely the richest?

Don’t know. Just know that almost every instrumented, angle valve, IO360 I’ve flown has those characteristics.

[redbaron1982]

So today I put everything back together with my AP and did a run-up and everything seemed fine.

One thing is that we had to adjust the throttle idle position. It was going all the way to 500RPM and running rough. We adjusted with throttle all the way back was idling at 750RPM. Anyway I usually idle at 1000RPM.

A test that I did, when doing the run-up at 2000RPM, I start pulling the mixture back, after RPMs peaking, I continue to lean and the RPM started dropping, I continue leaning until RPM dropped all the way 1500RPM but running smooth. I assume this is a good thing, I understand this gives an indication of even fuel distribution across al cylinders.

We will see in the next flight how it behaves. I plan on running the Savvy profile, that should give me some valuable information.

[PT20J]

Did you check the idle mixture? Usually adjusting the idle speed requires a mixture change and adjusting the mixture usually changes the idle speed so it can take a few iterations.

[Shadrach]

36 minutes ago, redbaron1982 said:

So today I put everything back together with my AP and did a run-up and everything seemed fine.

One thing is that we had to adjust the throttle idle position. It was going all the way to 500RPM and running rough. We adjusted with throttle all the way back was idling at 750RPM. Anyway I usually idle at 1000RPM.

A test that I did, when doing the run-up at 2000RPM, I start pulling the mixture back, after RPMs peaking, I continue to lean and the RPM started dropping, I continue leaning until RPM dropped all the way 1500RPM but running smooth. I assume this is a good thing, I understand this gives an indication of even fuel distribution across al cylinders.

We will see in the next flight how it behaves. I plan on running the Savvy profile, that should give me some valuable information.

You want to have your idle set to Lycoming specs regardless of where you set the engine for ground ops. If not, the plane will be more challenging to slow down and landing distances will be longer.

[MikeOH]

4 hours ago, Shadrach said:

Don’t know. Just know that almost every instrumented, angle valve, IO360 I’ve flown has those characteristics.

LOL!

Mine, too.  I was hoping you could tell me why!

[N201MKTurbo]

2 hours ago, MikeOH said:

LOL!

Mine, too.  I was hoping you could tell me why!

I think it may have to do with the length of the intake risers. They all come together in a nice square pattern in the sump, but I think there is a slight difference in lengths.  2 is the shortest, then 1, 4, 3. The intakes are in the front on the even (pilots) side and in the back on the odd (copilots) side. They all come together right behind the fuel servo.