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Fuel Injector Cleaning Help

Lt Dan

Well Known Member
I just got through my first cleaning of my fuel injectors per Lycoming SI 1275C.

I need some clarification regarding the reassembly and installation of the cleaned nozzles. The Lycoming service instruction states three different reassembly procedures depending on which part number nozzles you have:

"Step 6. Reassemble the nozzles as follows:
LW18265: In normally aspirated engines where the nozzles, P/N LW18265 (see Figure 2), are installed horizontally, particular attention must be paid to the identification marks stamped on one of the hex flats on the nozzle body. This mark is located 180° from the air bleed hole and must appear in the lower side of the nozzle to assure that the airbleed hole is on top in order to reduce fuel bleeding from this opening just after shutdown. To ensure nozzle is correctly torqued, tighten the nozzle to 60 in.lbs. torque. Then continue to tighten until the letter or number stamped on the hex of the nozzle body points downward."

My question essentially is: does this apply to me? Reasoning:
1) none of my nozzles are installed "horizontally"
2) my engine parts catalog shows my fuel injectors as P/N 63C26450

I have a Lycoming IO-360-M1B completely stock (Precision Airmotive fuel system). Each fuel injector nozzle on the IO-360 is installed nearly vertically. After torquing to 60 in.lbs., the "A"s are all over the place. One or more nozzles would take a considerable amount of extra torque to place the A at the "bottom." Not sure I want to apply that much torque if I don't absolutely have to.

Is P/N 63C26450 synonymous with LW18265? The description for LW18265 sure sounds like it matches my fuel injectors. The other two reassembly procedures they provide make it sound like those are definitely not my nozzles: LW14540, or LW18853, LW18854, LW18855.
 
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1. If your cylinders were matched to get peak egt all at the same time (by making small changes in the injector sizes) I hope you know which cylinder they each came from.
2. If they weren’t adjusted to make each cylinder peak at the same time, put it on your to-do list.
3. ‘Up’ for the injectors is generally taken to be +/- 45 deg.
4. I have seen a few posts suggesting that the holes be tipped slightly back, toward the firewall, to avoid any ram air pressures.
5. Yes, 60”lbs is a lot of torque, and I know some that have stopped at 50 if the hole is up. If you hit 60 in a bad orientation, sometimes starting over and cleaning the hole with a toothbrush can change the results.
6. Make sure you have the proper number and placement of the Adel clamps that hold the SS lines.
 
A finicky friend

Read what you read, got results that you got ie: where things lined up, none installed horizontally. He put same back in same as far as nozzles go. Only the last time he cleaned did he learn of the must be horizontally installed , “A” pointing down etc. . He couldn’t make it happen either and all his peak exactly the same time. I think you are fine. He cleans every oil change, no issues over 600 hrs new engine
 
Nozzle Orientation

These instructions came with my Airflow Performance FI system (uses Lycoming IO nozzles):
"Torque the nozzle body to 40 to 60 inch pounds. If the nozzle will be installed in any position other than vertical (discharge end down), tighten the nozzle to 40 inch pounds first then check for the position of the "A" stamped on one of the hex flats on the body of the nozzle. Continue to tighten the nozzle until the "A" points downward within a tolerance of one flat of the hex of the nozzle body. Do not exceed the maximum nozzle torque value when positioning the "A". This will position the air bleed hole in the body of the nozzle to face upward, and tend to keep fuel from dripping out the air bleed hole after engine shut down. Reinstall the fuel restrictor into the nozzle body before attaching the nozzle line."
 
From the Precision Airmotive manual for the EX-5VA1 FI system (I can't seem to copy and paste this, so here goes), p. 6 "Nozzle" details:

NOTES:
1) Install 1/8-27 NPT side of nozzle install into each nozzle or primer port of cylinder head. Torque nozzle to value in torque specification table using a clean deep well 1/2" 6-point socket.
2) The letter "A"stamped on one flat of the wrenching hex is located 180 degrees from the air bleed hole int he nozzle body. When installing nozzles in primer ports it is desirable to have the "A" facing downward, but the correct torque should take priority during installation.
...

Torque is 60 in-lbs. per table on p. 9.

ETA: I note that does say "primer ports", so perhaps it doesn't apply to "nozzles"?

And FWIW, I don't routinely remove and clean those nozzles anyway...they're being flushed continually with a pretty good solvent, avgas, so they only get cleaned on condition (which essentially means never). Same with the servo filter, per the manual.
 
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And FWIW, I don't routinely remove and clean those nozzles anyway...they're being flushed continually with a pretty good solvent, avgas, so they only get cleaned on condition (which essentially means never). Same with the servo filter, per the manual.

Ditto for me

Erich
 
Thank you all for the very helpful responses!

I’ll see if I can get the A at the bottom +/- one hex face by torquing between 40 and 60 in.lbs. If not, I probably won’t worry about it.
 
They don't need to come out very often. Last time mine were out was 2014.

Always thought the "A facing down" thing was dumb, not because the bleed hole (which can't be seen under the shroud) needs to face up (it does), but because it means you can't see the "A" when installed properly. That's why I use a center punch the first time they come out, marking the flat opposite the "A" with dots corresponding to the cylinder number. Kills two birds with one stone...you can see the marks during installation, and the nozzles don't get mixed up.

Same for the numbered workbench holder. Don't want to mix up the nozzles or restrictors after going to the trouble of matching the GAMI spread.
.
 

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And FWIW, I don't routinely remove and clean those nozzles anyway...they're being flushed continually with a pretty good solvent, avgas, so they only get cleaned on condition (which essentially means never). Same with the servo filter, per the manual.

I thought the best practice was to check the servo filter each annual. What if your rubber hoses, or something else, are breaking down and clogging up the screen. Not sure I'd want to figure that out by having the engine stop on me.

Larry
 
I thought the best practice was to check the servo filter each annual. What if your rubber hoses, or something else, are breaking down and clogging up the screen. Not sure I'd want to figure that out by having the engine stop on me.

Larry

Anybody ever read the manuals?

12.2 The airplane's fuel filter needs to be maintained to ensure that the servo gets clean fuel. The fuel filter inside the servo is a last chance filter. This filter does not need to be checked or cleaned unless it is suspected that contaminates (sic) have entered the fuel line after the aircraft's fuel filter.
(emphases added)

Precision Airmotive
Installation and Detail Specifications for the Silver Hawk EX-5VA1 Servo Kit
 
I'm confused. .why do you remove the whole injector to clean it? Isn't it easier just to pull out the orifice from the top and leave the threaded body in the cylinder?
 
I'm confused. .why do you remove the whole injector to clean it? Isn't it easier just to pull out the orifice from the top and leave the threaded body in the cylinder?

The screen must also be cleaned, which is the only reason I clean mine. The inside is always pristine but the outside gets dirty. Less air through the screen means reduced FF.
 
I just got through my first cleaning of my fuel injectors per Lycoming SI 1275C.

BTW, did anyone note the following on this SI?

TIME OF COMPLIANCE: At overhaul and as engine conditions require. Fuel nozzles can become clogged with a type of varnish from old fuel or from precipitate particles that are almost invisible to the naked eye. This condition may be indicated by rough engine operation, uneven idle, a cold cylinder, or an unusually high fuel flow indication on the gauge.
(Emphasis added)
 
I'm confused. .why do you remove the whole injector to clean it? Isn't it easier just to pull out the orifice from the top and leave the threaded body in the cylinder?

Yes. Again, in the manuals:

https://precisionairmotive.com/wp-content/uploads/2019/06/15-338e.pdf

p. 802 Section 8.1 E:

Remove fuel line union nut from nozzle. Remove fuel restrictor from nozzle body or nozzles indicated in Figures 5, 5A, 5B, 6A, 7 and 7A. It is not necessary to remove the nozzle body from the cylinder.
(emphasis added)
 
Cleaned an injector last week after I saw both CHT and EGT dropping simultaneously on one cylinder at power reduction. SAVVY analysis suggested to clean that injector. Torquing to between 40 & 60 & A down was no problem after really cleaning the threads on the injector and the cylinder threads with a Qtip & acetone.
 
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I thought the best practice was to check the servo filter each annual. What if your rubber hoses, or something else, are breaking down and clogging up the screen. Not sure I'd want to figure that out by having the engine stop on me.

Larry

Absolutely agreed. I plan to do it very soon. Where do you get the O-rings, etc that are necessary? What torque specs do you use and where can I find them?

Thanks!
 
Cleaned an injector last week after I saw both CHT and EGT dropping simultaneously on one cylinder at power reduction. SAVVY analysis suggested to clean that injector. Torquing to between 40 & 60 & A down was no problem after really cleaning the threads on the injector and the cylinder threads with a Qtip & acetone.

Good to know. And brilliant idea with the Q-tip. I wanted to clean mine but was concerned about allowing debris to fall into the cylinder. A Q-tip should do the trick nicely!

Did you get a chance to fly it again and see if the problem is fixed?
 
Did you get a chance to fly it again and see if the problem is fixed?[/QUOTE]

I did a short flight and the EGT and CHT on Cyl 4 were doing what they should be doing looking at the engine monitor.

I’ll do another GAMI lean test and In-Flight Mag Check as soon as the weather clears - it’s pretty cold & snowy here now. I’ll download the data to SAVVI and get their input again. Those SAVVI graphs are great for troubleshooting.
 
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