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NPT length

G

Gary's RV7A

Active Member
Ok, I understand aluminum fittings on oil coolers are bad...

My question, is there a shorter length fitting (steel) that I can use on my oil cooler so I have clearance from the lower cowling. I have to use a higher capacity (clone 8432) oil cooler because I installed a IO-375. See picture below:

0d34ad40649e5f1f5c4e2abd5c155337_zps899d8851.jpg
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Last edited:
How much clearance do you want, 1/8"? More?

One thing to start with is the thread engagement on that boss. It might be perfect, but it seems to stand tall.

http://www.engineersedge.com/hardware/taper-pipe-threads.htm

Here is a link to thread engagement dimensions. Just a suggestion, you might check this to see if they are correct now. If too little, it goes the opportunity to tap the boss deeper. 1/2" pitch is 14 TPI and that is a .143" for two threads deeper.

Good luck. When experienced guys weigh in, you will probably learn more.
 
Most of the rear baffle mounted coolers I have seen have the oil cooler fittings on the inboard side, not the outboard. Not that it has to be that way - but it would eliminate your problem to flip it around.

Paul
 
can you flip your oil cooler 180 degrees so the fittings are on the opposite side from the cowl?

edit:paul beat me to it...
 
inlet and outlet are 180 degrees a part

Flipping the oil cooler 180 degrees does no good, have the same problem on the other side.
 
NPT tap

Hi Bill, That might work if I could find the right size of tap. The oil cooler has a good 1/2 inch of material with threads. If I could use all the threads on the fitting, I would have enough clearance to continue. It doesn't seem to engage more a 1/4 inch. Thanks for the suggestion.



BillL said:
How much clearance do you want, 1/8"? More?

One thing to start with is the thread engagement on that boss. It might be perfect, but it seems to stand tall.

http://www.engineersedge.com/hardware/taper-pipe-threads.htm

Here is a link to thread engagement dimensions. Just a suggestion, you might check this to see if they are correct now. If too little, it goes the opportunity to tap the boss deeper. 1/2" pitch is 14 TPI and that is a .143" for two threads deeper.

Good luck. When experienced guys weigh in, you will probably learn more.
Click to expand...
 
On my 7 with the IO-375 I could mount the oil cooler with the fittings on the inside. It is an Aero-Classic 9row Part #8000074. The engine mount on the 7A might be different however. Disregard the aluminum fitting on the pic:

 
Dumb question

I am not nearly to that point yet, still building fuselage, but...
Why are aluminum fittings on oil coolers bad?
 
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