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  #1  
Old 07-20-2018, 02:55 PM
Nova RV Nova RV is offline
 
Join Date: Aug 2015
Location: Leesburg, VA
Posts: 264
Default FM-150 snorkel fit adjustment

The snorkel does not sit perfectly square on the FM-150 since the servo sits out further than the stock Bendix style servo. This is how "I" modified my snorkel to fit, there may be an easier / better way but since I was asked how mine was installed here goes and a level of comfort doing simple fiberglass layups helps: When you bolt the snorkel to the FM-150 it will cause the snorkel to be approximately 7/16 too far forward when you get to the air filter assembly and the snorkel will not slide inside per plans. To start I made an initial trim to length of the snorkel. (this pic shows the snorkel square and was taken before I tightened the snorkel to the FM-150)


Next is to slit the corners of the snorkel so that you have 4 sides that you can move easily. These slits shown are preliminary, the final ones were several inches long - follow the contour of the snorkel.


Trim the tabs on the filter frame approximately in half, they are angled and won't allow the snorkel to fit with the adjusted snorkel sides. There is still plenty of flange to secure the snorkel


With the snorkel bolted to the FM-150 you can now screw the filter flange to the baffle and then push and hold each side of the snorkel against the filter flange and drill/cleco just like in the plans. Remove everything and epoxy the individual sides to the filter frame. Your snorkel now should fit without any tension but look like a mess because you have long cuts in each side. Scuff the outside only and apply epoxy and fiberglass over each cut then apply larger pieces to cover the entire upper snorkel. Several layers of 7.5oz cloth should do it. Don't add any cloth inside the snorkel.


Fill each slit gap from the inside with epoxy and flox and sand to maintain a smooth inside contour. (this pic shows inside prior to filling the slits with epoxy/flox)


Bolt all back on and you are finished.

yes, I know the plastic comes off of the filter before use

The final snorkel has the same intake area below the filter and nearly the same airflow pattern so I can't imagine there is any measurable difference in airflow from the filter to the fuel servo.
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Chris Moon

Leesburg, VA
RV-14A kit # 140243 (flying as of 11/18)
VAF 2018 and 2019 paid
www.mykitlog.com/chrismoon/

Last edited by Nova RV : 07-20-2018 at 02:58 PM. Reason: typo
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  #2  
Old 07-20-2018, 05:08 PM
Nova RV Nova RV is offline
 
Join Date: Aug 2015
Location: Leesburg, VA
Posts: 264
Default

Oops, forgot to show pic of completed installation (less a few screws).
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Chris Moon

Leesburg, VA
RV-14A kit # 140243 (flying as of 11/18)
VAF 2018 and 2019 paid
www.mykitlog.com/chrismoon/
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  #3  
Old 07-20-2018, 09:38 PM
Jake14 Jake14 is offline
 
Join Date: May 2014
Location: Seattle
Posts: 191
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Nice work. Some of us had problems aligning the filter lip with the lower cowl inlet ramp (see the thread "Cowl fitting and the inlet ramp" on this page) You may be able to correct the alignment with the cowl ramp (if needed) using this technique and save yourself some grief later if you can check the cowl alignment now
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  #4  
Old 09-14-2018, 10:32 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
Posts: 645
Default

I'm glad this writeup is here. I got the Thunderbolt engine and didn't understand that when I got the FM-150 I was also due for a special adapter kit for the cables, and extra days refitting the snorkel.

Did you fit up the throttle end of the snorkel at the time of the rough cut even with the filter box? Seems like that end would need to be very fixed to make the rest work.

What is the best way to make sure the snorkel is lined up right on the throttle body to make the hole concentric with the intake?
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  #5  
Old 09-15-2018, 12:12 AM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 2,508
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Quote:
Originally Posted by JDA_BTR View Post
I'm glad this writeup is here. I got the Thunderbolt engine and didn't understand that when I got the FM-150 I was also due for a special adapter kit for the cables, and extra days refitting the snorkel.

Did you fit up the throttle end of the snorkel at the time of the rough cut even with the filter box? Seems like that end would need to be very fixed to make the rest work.

What is the best way to make sure the snorkel is lined up right on the throttle body to make the hole concentric with the intake?
The snorkel fitting shouldn’t take long at all and due to variation in snorkel different people have had more or less modification needed.

I have the same engine as you, thunderbolt.

I was going to adjust the snorkel to the airbox as it is done here but it would take more of a cut and butchering of my snorkel. So I cut the snorkel at the neck where it attaches to the throttle body. I had the flange attacked to the throttle body and the snorkel nicely attacked to the airbox. Then floxed the flange back to the snorkel. With a bit of cleaning, It came out perfect fitting and very clean.
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  #6  
Old 09-15-2018, 05:44 AM
MED MED is offline
 
Join Date: Jul 2015
Location: Aiken, SC
Posts: 313
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I did the same as Bavafa, but used a piece of florist foam to hold the alignment between the throttle and the throttle end of the snorkel. It worked out fine, but was my first attempt at this kind of "major" Fiberglas surgery, so I was worried the entire time.
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  #7  
Old 09-15-2018, 03:13 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
Posts: 645
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I considered cutting at the flange side but figured my skills were better with a filter side cut. So now the snorkel is sliced up but fits well and clecos in place. Tomorrow I plan to wrap the assembly with a couple of layers of glass then lay flox on the inside to smooth it out. Is there a minimum number of layers for the wrap? Anything special to watch for?
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Final Assembly....
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  #8  
Old 09-15-2018, 07:56 PM
Nova RV Nova RV is offline
 
Join Date: Aug 2015
Location: Leesburg, VA
Posts: 264
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Quote:
Originally Posted by JDA_BTR View Post
I considered cutting at the flange side but figured my skills were better with a filter side cut. So now the snorkel is sliced up but fits well and clecos in place. Tomorrow I plan to wrap the assembly with a couple of layers of glass then lay flox on the inside to smooth it out. Is there a minimum number of layers for the wrap? Anything special to watch for?
I think I used about 3-4 layers of 7.5oz cloth covering the areas that were slit and a large piece wrapped over the whole area and it was more than enough to match the rigidity of the original part. I did also add flox mixture inside to smooth it back out.
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Chris Moon

Leesburg, VA
RV-14A kit # 140243 (flying as of 11/18)
VAF 2018 and 2019 paid
www.mykitlog.com/chrismoon/
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  #9  
Old 09-29-2018, 12:11 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
Posts: 645
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My snorkel layup is done and I think acceptable. It changes where the alternate air inlet should be placed because it is too far aft if I follow the dimensnsions on page 47-19.

What are the critical issues in hole location for the alt air? I’m thinking to keep the same vertical dimension and just move it forward 3/4 inch to fit better.

I also notice that in the drawing on page 47-19 and the next page with the flange flat and the neck of the va-192a sticking into the hole that the flange holes are mirrored from what the pic shows. Nutplate holes are correct.
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Ser 104142, RV-14A
N1463
Final Assembly....

Last edited by JDA_BTR : 09-29-2018 at 02:22 PM.
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  #10  
Old 09-29-2018, 12:45 PM
Bicyclops Bicyclops is offline
 
Join Date: Oct 2012
Location: LA, California
Posts: 178
Default Diameter?

When I was helping a guy with his snorkel and FM-150, the first thing that jumped out at me was the small diameter of the snorkel outlet at the servo end. The FM-150 has a larger diameter inlet than the Bendix unit. We built it up around the narrow "neck" and then hogged it out to match the servo. This was after dealing with the fit at both ends.

Ed Holyoke
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