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  #1  
Old 05-19-2011, 02:18 PM
RVG8tor's Avatar
RVG8tor RVG8tor is offline
 
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Question Homemade restrictor fitting

I need a restrictor fitting for the manifold pressure line, only 2 supplied with the FWF kit (one each for Oil and Fuel) Van's sells them for $19.50 (VA128) but I read how some guys make them on this forum. I don't own a #60 bit the closest I can some up with is 1/16". So is there anything magical about the .040 hole in the restrictor Van's sells.

The restrictor is there to prevent a catastrophic leak of air if one of the lines connected to it break, so a 1/16" hole would allow a slightly bigger leak over a .040 hole but should serve the same purpose yes?

I have the fitting threaded and will JB weld the bolt into the fitting then cut off the end.

Cheers
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  #2  
Old 05-19-2011, 02:42 PM
SteinAir SteinAir is offline
 
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Quote:
Originally Posted by RVG8tor View Post
I need a restrictor fitting for the manifold pressure line, only 2 supplied with the FWF kit (one each for Oil and Fuel) Van's sells them for $19.50 (VA128) but I read how some guys make them on this forum. I don't own a #60 bit the closest I can some up with is 1/16". So is there anything magical about the .040 hole in the restrictor Van's sells.

The restrictor is there to prevent a catastrophic leak of air if one of the lines connected to it break, so a 1/16" hole would allow a slightly bigger leak over a .040 hole but should serve the same purpose yes?

I have the fitting threaded and will JB weld the bolt into the fitting then cut off the end.

Cheers
There are many ways to go about building your own restrictor fitting and they all work pretty well. In the MP, it's no so much for an air leak (don't think that an open MP line would be anywhere near catastrophic), but to settle down the sensetive MP instruments. Some of them are so sensetive they'll register each intake stroke and it gets quite annoying without that restrictor in there. The FP and OP are much more critical from a leak standpoint than the MP is, but the MP is much more sensetive to variation in pressure readings (my point is the orifice size for the MP isn't a critical thing other than to smooth out pulses, not necessarily for leaks).

I say do what you can and go fly. If you MP instrument isn't too jumpy then you'll be golden.

Just my 2 cents as usual,

Stein
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  #3  
Old 05-19-2011, 02:48 PM
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dpansier dpansier is offline
 
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Drilling a very small hole can be difficult without the proper tools.
Wire feed welders use a very small tip .020", .025" and up, this tip could be used to make a restrictor.
If you know a welder you may be able to accrue one as they usually toss them out after a short use.
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  #4  
Old 05-19-2011, 02:48 PM
AirbusPilot AirbusPilot is offline
 
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I used a hypodermic needle welded inside a brass tube. that is air models turbines techniques
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  #5  
Old 05-19-2011, 03:02 PM
TS Flightlines TS Flightlines is offline
 
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Smile try this--

Use a piece of 1/8 tubing, flare one end (so it fits snug in the fitting), then you can JB weld or braze it in place. Cut off the excess to make a nice end.
Takes a couple of minutes.
Tom
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  #6  
Old 05-19-2011, 03:05 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
 
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Mike,

Not homemade, but here's a cheap version from Wicks.

http://www.wicksaircraft.com/catalog...767/index.html
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  #7  
Old 05-19-2011, 04:51 PM
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RVG8tor RVG8tor is offline
 
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Default Hole size is the question

I am making mine like I read from someone on this site. I tapped the inside of the fitting to 10-32. Then drilled the hole (1/16" diameter) down the center of a #10 bolt. With a litle JB weld I threaded the bolt into the fitting. When it sets up after 24hrs I will use a cutoff wheel to cut the bolt off at the end of the fitting.

I noted that Van's and other restricters used a .040 hole size. I do not have a #60 drill so I made a larger hole with the 1/16" bit I had on hand. I will just try this for my manifold pressure line, if it fluctuates too much then I will know there is something to the hole size.

Cheers
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  #8  
Old 01-06-2018, 02:19 PM
rv8ch rv8ch is offline
 
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Default Did it work?

Hi Mike, Did it work ok? Thanks!
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  #9  
Old 01-06-2018, 04:31 PM
BillL BillL is offline
 
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Quote:
Originally Posted by rv8ch View Post
Hi Mike, Did it work ok? Thanks!
Low cost orfice - pick your size.

http://blp.com/cart/index.php?main_p...oducts_id=1495
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  #10  
Old 01-06-2018, 05:21 PM
rv8ch rv8ch is offline
 
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Default Brilliant!

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Originally Posted by BillL View Post
Very cool - just ordered a bunch - thanks!
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