Ironflight

Ironflight

VAF Moderator / Line Boy
Mentor
Quick question -

I am building up an AN816-4D as a restrictor to mount in Louise's engine for a new oil pressure sense line - I blocked it up with an appropriate sized rivet, and now need to drill a hole through it - any idea what a good orifice size is?

Paul
 
Paul,

According to their website, the restrictors Van's sells have a 0.040" hole.

mcb
 
Paul, Going from memory here so use at your own risk!

I was told by Bart at Aerosport to drill about an .020 diameter hole but he also said it's pretty tuff to do and he was right! It's also tuff to find a .020 drill which is #76 drill.

Again going from memory I believe I ended up drill an .032 hole which is a #67

These drills break really easy, even in aluminum!!

Good luck

Ted
 
Paul, I just used the smallest one that wasn't broken in my box of numbered drills. 60 if you still have it, but anything in the 50' will work. Use a dremel on high speed to drill it. They break to easy if used in a regular drill.

Vic
 
"Machine Screw" length drill bits also help. They are much shorter and hence stiffer across the entire size range.
 
vic syracuse said:
... the smallest one that wasn't broken in my box of numbered drills. 60 if you still have it, but anything in the 50' will work. ...
Click to expand...

It's amazing how often I have used that criteria in drilling a small hole...;)

Thanks folks, I'll see what's left in the small end of the box and chuck it up in the Dremel.

Paul
 
If you need small drills...

you can get them at any hobby store. I just bought a full set for about $4.00 after I dropped my old set and lost a lot of what wasn't already missing :D
 
I have the AN816-4D's from Vans, one for fuel pressure and one for oil pressure and I believe they are drilled out at .040.

A smaller hole would be better. The first time I pressurized the fuel system pressure should have been 25 psi but settled down at 8 psi. I had failed to tighten the -4 pressure line at the pump fitting and it sprayed fuel all over the firewall and aft side of the engine. What a stupid mistake that was.

It was luck, one more time, that the whole thing did not blow up with the master relay and battery right there. :(
 
Rivet? What Rivet?

Now that the hole size has been more-or-less specified, would someone please explain what size rivet is used and how? Is it pressed in or what? And which end of the AN816-4D?

Thanks,
Joe
 
Go see a jeweler, Paul.

I owned a jewelry store for 15 years and we always had a full set of itty-bitty drills for mounting stones/diamonds, etc.

Regards,
 
Ironflight said:
Quick question -

I am building up an AN816-4D as a restrictor to mount in Louise's engine for a new oil pressure sense line - I blocked it up with an appropriate sized rivet, and now need to drill a hole through it - any idea what a good orifice size is?

Paul
Click to expand...

Is this a trick question? The pressure is the same no mater what the hole size is (you are not measuring the pressure at the orifice). The only reason to put in the restrictor is to restrict the flow (hence the name) in case the hose or gage spring a leak. It minimize the amount of oil pumped out of the engine. Therefore my answer is the smallest hole you can drill.
 
plehrke said:
Is this a trick question? The pressure is the same no mater what the hole size is (you are not measuring the pressure at the orifice). The only reason to put in the restrictor is to restrict the flow (hence the name) in case the hose or gage spring a leak. It minimize the amount of oil pumped out of the engine. Therefore my answer is the smallest hole you can drill.
Click to expand...

Ah...but the smaller the hole size, the longer it might take pressure to come up, oil being viscous! Shouldn't make any difference once the system is full of oil, of course. I think I finally got it done with a #50 - anything smaller just felt like I was going to snap it off.

Paul
 
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