Conn 14J Mods

[largobone]

I've decided I'm going to start modifying my Conn 14J that I got to learn Eb, so I've started brainstorming some things for the project. However, there are some discrepancies that I'm struggling with, especially in regards to bore size. I want to turn the 3-valve top action horn into a 4 or 5-valve front action horn, so I've been looking for some valvesets to have cobbled together.

According to Conn Loyalist, the 14J has a Conn #7 bore, or .625. However, according to my own measurements, it comes out closer to .67 approximately, measuring from the 2nd slide. I'm hoping for the latter, as it is far easier to find valve blocks in that range than the former. I was thinking of a .687 King fourth valve.

As for the fifth valve, where can I locate a rotary valve just slightly larger than that?

I'm hoping Mark can chime in here, as my project seems to be very similar to yours

[largobone]

I've been window shopping Ebay for parts for now, but I might also be able to talk my director into selling a school horn or two to me, since they just sit around and one needs major repairs anyway.

1. Olds O20 sousaphone (BBb)-Not totally sure on bore size of this horn so might work, might not. I really like Olds valves, and the sousas in general, so this would be awesome for the first 3 valves.
2. King 1240 tuba (also BBb)-Definitely a .687 bore; the first valve on this horn is dented and WAY out of align (like, you need a mallet to get the valve out) and school doesn't have the funds to do a repair like that on some 3-valver that's never gonna get used. I think it'd be easy to buy this horn from the school, then take the 2nd valve and scrap the rest.

How should I approach my director with something like this and how much should I have to offer?

[largobone]

What part of the second valve are you measuring at?

I'm measuring the inside of where the slide goes in.

The biggest turnoff for Ebay is the crazy-high shipping on most horns. Sometimes that costs as much as the horn itself, and I can't go driving more than a couple of hours to pick a horn up. I'll keep looking there and hope the school horns work out, but good point on the fiberglass sousas.

Thanks for the sources on the 5th valve rotors, Lots of good options there. I think I'll check with whoever I end up having do the work before I pick one out, see what they think is best. That will probably be Lee Stofer; I'll be calling him soon once my plans are a little more organized.

[roweenie]

That model should be .625 (5/8") I.D. at the inside tubing (that's where the bore is measured).

[largobone]

Got it. In that case, making everything before the bugle just a little larger (.687/9) wouldn't drastically change anything right?

[roweenie]

No idea. Approach it as a prototype.

+1

No way of knowing until it's done.

[largobone]

Awesome! Thanks