# Vacuum pump mounting studs.

Discussion in 'Firewall Forward / Props / Fuel system' started by bifft, Oct 14, 2014.

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1. Oct 14, 2014

### bifft

#### Well-Known Member

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Working on hooking up the engine to my RV, I want to use a B&C accessory mounted alternator, with their VAC-2 oil pickup:

http://www.bandc.biz/pdfs/quickfacts_vac2.pdf

This will require 3.25 inch or so studs. The old engine I have only has one 1-7/8 stud, so I need to aquire the rest. The cheapskate in me wants to run down to the aviation department of my local DIY place and get a threaded rod and cut to length, but that probably isn't a good idea. Actual Lycoming studs are $40 each: Stud .250-20 X 3.00 Long - 25C-24 - Aircraft Specialties Services Where I can buy "black oxide spacing studs" with tensile strength of 125k psi at McMaster-Carr for$1.71, or stainless at 10/\$9.12. (need four of them).
Is this a case where we really need the lycoming blessed with magic airplane dust part? I suppose the worst case is my alternator falls off while inverted and all my oil drains out.

2. Oct 14, 2014

### dcarr

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Location:
Austin, TX
I think that the factory studs have a slightly different thread pitch at the accessory case end that makes them a tight fit so they don't unscrew in use. You might be able to use Loctite or similar to duplicate this effect if the threadlocker can tolerate the temperature. Another idea would be to try calling a few engine shops or salvage yards to see if they have any used ones to sell.

David

3. Nov 1, 2014

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