Fox 15

[Elwyn Aud]

What is the size of the back-plate bolts on the old Fox 15?

[Andrew Hathaway]

Just shooting a best guess... 3-48?   From what I've seen when Fox uses something smaller then 4-40 it's usually 3-48.

[Jim Kraft]

Andrew is right Elwyn. If it is an old steel fin, or the later slant plug, it is 3-48. I just checked mine. I think the head bolts are 3-48 also, but who can get those little buggers out with their little bitty phillips heads all stripped out. You might have to go to McMaster Carr to get them as 3-48's are scarce as hens teeth anymore.

[Tom Luciano]

the size is a odd ball phillips that strip very easy
Sorry Elwyn I couldn't resist but I will be doing the same on the head of a 36x

Tom

[Bill Gruby]

 Elwyn;

 Yes 3-48 is the size.  I get mine from Ro Brand. I believe you can get them from Fasten All to.

 "Billy G"

[Tom Luciano]

Elwyn,

I just looked at microfasteners.com they have 3-48 various Lengths in stock. you can order in qty. of 10 or fifty I buy all my bolts from them.  I have not experienced any problems with their products.


Tom

[De Hill]

How many do you need, Elwyn?

[Elwyn Aud]

4

[De Hill]

Are you coming out to the field on saturday or sunday?

I can bring you 4 of them then.

Do you need gaskets?

[Elwyn Aud]

Hope to get out Saturday. The gaskets are still good.

[De Hill]

See you saturday.

Bring the engines!

[dennis lipsett]

Hope to get out Saturday. The gaskets are still good.

Elwyn,
It's usually better to replace the gaskets if you take the engine apart. Old fibre , paper, cork, gaskets
usually are compressed when used and don't as well if reused, The correct screwdriver is I believe a #1 phillips.Duke used to sell screwdrivers for his engines to deal with the complaints of stripped heads on the screws.
dennis

[Elwyn Aud]

This sure doesn't look right. I was going through a few Fox 15's the other day and noticed 2 of them had an exceptionally small inlet hole on the needle valve assembly. One of the 15's was an older one with a pressed in needle valve assembly and the other was a later model with a screwed in nva.  I don't think I've ever ran the ones with the small inlet hole but it sure looks incorrect. Here's a picture with normal looking inlet hole with one of the smaller holes.

[Andrew Hathaway]

I've got a couple of both... I just assumed Fox machined them differently at some point. 

[Alan Hahn]

This sure doesn't look right. I was going through a few Fox 15's the other day and noticed 2 of them had an exceptionally small inlet hole on the needle valve assembly. One of the 15's was an older one with a pressed in needle valve assembly and the other was a later model with a screwed in nva.  I don't think I've ever ran the ones with the small inlet hole but it sure looks incorrect. Here's a picture with normal looking inlet hole with one of the smaller holes.

I think the small hole was special for the Fox15 hurl contest---it keeps the dirt clods out of the spraybar and the small hole doesn't interfere with the aerodynamics of a spinning Fox.

Actually it looks like they forgot a step in the machining process. That small hole represents the seating diameter, where the needle pokes through. Normally you would open up the hole on the fuel tube side. I know that because I made a few $100 spraybars with my mini lathe.