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Old Aug 06, 2012, 02:19 PM
That's so classic you.
Generic Member's Avatar
United States, NC, Stokesdale
Joined Jul 2006
330 Posts
Help!
Macs thin-wall pressure fitting - how to install?

How do you get the threaded end in the hole from the inside of the pipe? I tried just putting in the inlet side of the pipe and jiggling it around hoping it would fall in place.
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Old Aug 06, 2012, 02:25 PM
Registered User
Hawaii
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Quote:
Originally Posted by Generic Member View Post
How do you get the threaded end in the hole from the inside of the pipe? I tried just putting in the inlet side of the pipe and jiggling it around hoping it would fall in place.
Temporarily glue the piece onto a long thin piece of wood. Break off the wood piece and pull out after you tighten the assembly.
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Old Aug 06, 2012, 02:31 PM
That's so classic you.
Generic Member's Avatar
United States, NC, Stokesdale
Joined Jul 2006
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Nice! Thanks, I'll try that.
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Old Aug 06, 2012, 03:30 PM
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United States, AZ, Mesa
Joined May 2003
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1) I cut about foot and a half of .020 safety wire (or any other like wire), wad up about the last inch on one end into a ľ ball.
2) Slide the thin wall threaded tube on to the wire, flange down, until itís caught by the ball at the end of the wire.
3) Fish the wire into the pipe and out the drilled hole. Pull the wire thru until the fitting is pulled thru and seated.
4) While keeping pressure on the fitting, slide the 1st nut down the wire and snug it up. Pull the wire out.
5) Thread the 2nd jam nut on, leave loose. Thread the 90 degree fitting on and snug.
6) Tighten the 2nd jam nut up against the fitting.
7) While holding the fitting with a wrench position to the desired direction and tighten the 1st jam nut against the pipe.

Pretty wordy but itís easyÖ
Eric

P.S. Use your favorite thread lock.
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Old Aug 06, 2012, 03:36 PM
That's so classic you.
Generic Member's Avatar
United States, NC, Stokesdale
Joined Jul 2006
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Another excellent idea.

Thanks guys!
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Old Aug 07, 2012, 01:37 AM
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Roguedog's Avatar
United States, CA, Norco
Joined Feb 2007
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Nix the pressure fitting and use a Perry Pump with the fitting to the crankcase.

Solves the problem of trying to use the tuned pipe exhaust pressure wave to pump up the tank. Also saves you from ruining that pipe by drilling a hole in it Plus the tank stays vented to the atmosphere. No need for a pressurized tank.

Biggest plus of all is positive fuel delivery at all times and provides increased preformance at top end.
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Old Aug 09, 2012, 12:58 AM
KE your cub.
Curare's Avatar
in the gutter, again....
Joined Jun 2005
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Or buy a 61 P!
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Old Aug 09, 2012, 06:10 AM
That's so classic you.
Generic Member's Avatar
United States, NC, Stokesdale
Joined Jul 2006
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Im working on a pipe for an OS 25VF DF to put in my MK Skymaster 20. A 61SFp would be a tight squeeze! :-)
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Old Aug 09, 2012, 10:05 PM
KE your cub.
Curare's Avatar
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Hehehe, but not impossible.

I do question slightly the need to have the pressure nipple at the fattest part of the pipe, a lot of my headers have the nipple about 1/2" away from the mounting flange.

What is the reason for having the nipple there? Does having 12" of fuel tube back to the tank diminish the return?
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Old Aug 13, 2012, 01:19 AM
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United States, CA, Norco
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Quote:
Originally Posted by Curare View Post
Hehehe, but not impossible.

I do question slightly the need to have the pressure nipple at the fattest part of the pipe, a lot of my headers have the nipple about 1/2" away from the mounting flange.

What is the reason for having the nipple there? Does having 12" of fuel tube back to the tank diminish the return?
I don't know for sure but since the purpose of a tuned pipe is to reflect a pressure wave back towards the engine to force the portion of fuel charge that escaped out the exhaust port back into the combustion chamber (Supercharging) I would say that putting the nipple in the header could cause a disruption in that pressure wave and thereby reduce the effectiveness of the tuned system. Wheeewww! Did I say that?

Having the nipple at the fattest part of the pipe or the widest part of the expansion chamber, it seems to me, would be the best place for it as the pressure wave being reflected back toward the engine would have more of a pure form if you will. Nothing to defract or deflect the wave as it makes it way backward toward the engine and moves the charge back into the combustion chamber.
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Old Aug 13, 2012, 04:56 AM
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Hmm

Food for thought.
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Old Aug 13, 2012, 12:52 PM
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United States, TX, Hutto
Joined May 2012
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Back in the day I would drill the hole for a tight threaded fit, and J-B weld the fitting to the pipe. Never a problem.
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Old Aug 14, 2012, 02:02 PM
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stuntflyr's Avatar
Los Angeles
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Quote:
Originally Posted by Roguedog View Post
I don't know for sure but since the purpose of a tuned pipe is to reflect a pressure wave back towards the engine to force the portion of fuel charge that escaped out the exhaust port back into the combustion chamber (Supercharging) I would say that putting the nipple in the header could cause a disruption in that pressure wave and thereby reduce the effectiveness of the tuned system. Wheeewww! Did I say that?

Having the nipple at the fattest part of the pipe or the widest part of the expansion chamber, it seems to me, would be the best place for it as the pressure wave being reflected back toward the engine would have more of a pure form if you will. Nothing to defract or deflect the wave as it makes it way backward toward the engine and moves the charge back into the combustion chamber.
Hi Bryan,
I have my FSR on a Macs pipe as you've seen. I was questioning the same thing and for simplicities sake was directed to drill a hole in the header block just as it leaves the exhaust. Tony F said it'd be fine and it always has been. My guess is that there is a lot of high velocity air there that cannot be disrupted to any large extent by the tiny orfice there, provides positivepressure to the tank for sure, and the down side being that it is hot. The fuel tubing is a little discolored after about 60 flights.
Chris...
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Old Aug 15, 2012, 12:43 AM
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United States, CA, Norco
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Hey Chris,

Interesting conversation.

I was a Calibration Technician for 4 years and the main focus of my job then was calibrating Liquid Flow Meters for different types and sizes of pipe e.g. pvc,cast iron steel pipe etc. One of the first things I learned was that the average flow in most pipe is around 10% into the pipe from the side or 10% from the inside wall.

The inside surface of the pipe causes a significant amount of friction or resistance to fluid flows and is fastest in the middle of the pipe. Most Flow sensors need to be set into the pipe at the 10% location to get accurate measurement data. It may be different for gaseous vapors as compared to a liquids. I was using the 10% theory in my guesstimate for the pressure wave.

If the nipple is threaded into the the the bracket it may not protrude into the flow to cause any difference or since it's right at the bracket that's where the excess fuel charge would be anyway so probably wouldn't make a difference.

As far as placing the nipple at the widest postion of the pipe it's not a very clean look with all that extra fuel line running back to the engine. I invested in a perry pump for this reason. No need for a nipple on the pipe or the header provides a neat clean look, tank vented to atmosphere so you can hide the vent if wanted, pump can be hidden in front of tank, tank location anywhere you want (on CG for instance) can adjust the pump pressure depending on outside temp or time of year if needed.
Bryan
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Last edited by Roguedog; Aug 15, 2012 at 01:43 AM.
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