Brass petcock refurbishment

[matt glascock]

Hey all, This has likely been covered before, but not that I could find on an index search. I really like the look of the brass petcocks, but have changed almost all of the on my toaster tank Hodies to pot metal petcocks due to nearly universal fuel weeping. I don't like fuel weeping. It seems like a set-up for am impromptu weenie roast. I don't like those either. I thought about filling the cavity with rouge or lapping compound and twirling the valve around about a million times to lap a better mating surface but my "ingenuity" seems to create mayhem as often as not. Any suggestions for salvage of these neat brass valves would be appreciated.

[MTrat]

I like them. You can lap them as mentioned. Don't tighten them too tight. 'Index' the final handle location by sanding the gasket to reduce thickness.

[matt glascock]

I'll give it a shot, M. Thank you!!

[Bullfrog]

From my experience, you'll need good luck in addition to the TLC you are planning on investing in your brass petcocks.

I've found the lapping to be a semi-interesting and semi-tedious operation which most often results in no net gain in proper operation. In addition, finding the "magic spot" for tightness of the petcock cone is elusive. Usually, when tight enough to stop weeping . . . it is too tight to turn. Back off the tightness a nano-degree to allow actually operating the petcock . . . and the weeping returns. A lubricant designed for use on fuel valves helps both ease of rotation AND to stop weeping . . . for a little while.

There is a reason for the later design of fuel petcocks. They aren't quite so British-traditional looking, but they don't embody the traditional British tolerance for leaking fluids either.
Ed

[Bill2001]

Lapping may help if there are pits or grooves. But mostly lapping is feel-good work. For rough lapping I find that Bon-Ami cleanser works well. It uses the mineral Feldspar which is only slightly harder than brass or tempered aluminum and it doesn't scratch or cut too deeply. For fine finishing use auto paint polishing compound.

[matt glascock]

Thanks fellas. I have perfectly functioning pot metal petcocks not. I guess there was probably a reason for the "new and improved" valves. I might fiddle around with one using the bon ami approach and see what happens, but when the day is done, I'd have to endorse proper function over the cool brass equipment. Thanks all!

[Bill2001]

I have a pair of weepy brass petcocks that I'll refurbish and use "for show" with my near-pristine chrome tank. For my day-two-day riding I'll use my patina'd denter and potmetal pets.

[matt glascock]

Good call, Bill. I have a really nice early Super Rat toaster tank that I retired (luckily dent-free) after three seasons. I'll do the same as you.

[sparkyj]

Guys, on my 69 Ace 100 tank I have the brass petcocks the right side opens, weeps a tad bit. The reserve side is completely stuck in the off position. The tank has been sloshed with what looks like Red-Kote (its red and rubbery). Before I go twisting things about, I need to know how these operate. Is there a replaceable gasket that makes the seal? For the stuck side, is it safe to use the nut end to try and crack the stuck-ness? Would be nice to "pre visualize" this before twisting my nuts!

[Bert44]

I've recently pulled mine apart. They are very simple. Basically there is a tapered hole in the brass body and the tap is a tapered plug which matches the hole. The nut draws the taper into the hole to give an interference (therefore theoretical leak free) fit. I used fine household cleaner to lap the two together.
With your stuck peacock light heat and gentle tapping should free the taper but be careful not to use too much power as it is only brass which is soft and you could bend or damage the thread.

[sparkyj]

Sounds good. Will try a heat gun on low setting. I assume its ok to use a wrench on the nut to do the turning (?).

[Bullfrog]

Um, depending on turning the petcock nut to move/rotate the tapered core does not sound like a good plan to me. The nut is there to draw the tapered core into the tapered hole. Turning the nut should either loosen or tighten the nut - it should have no effect on rotating the core piece (especially if the petcock is "locked up"). Of course, loosening the nut will allow the core piece to "back out" of the tapered bore to aid in freeing it up. Use only the petcock "handle" to provide rotational torque to the core piece.
Ed
PS: See recent thread on re-furbing Hodaka brass petcocks for additional information.

[sparkyj]

Perfect. thanks

[Al Harpster]

I spent some considerable time lapping two brass petcocks.

I don't know if the OEM ones allowed the little handle to be removed.

The after market ones I bought allow the handle to be removed and that allowed me to chuck the big end of the male part in a variable speed drill.

Driving the male tapered end with a motor saved my fingers.

That allowed me to do A LOT of lapping with fine compound. The standard valve lapping compound sold in tubes at Auto Zone was way too coarse.

I made my own compounds with various grades of buffing compounds and motor oil as the carrier. You want something quite fine. The standard valve lapping compound sold in tubes at Auto Zone was way too coarse.

Sounds crazy, but the winters here can be long and cold. Not much going on. And I don't like being beat by something like this.

Here's some pictures that may show the finish I achieved that stopped the leaking.

But after I had lapped enough off, the male plug went further into the tapered hole. Because in lapping the hole it gets bigger. Then there was not enough thread length to tighten it in place.

So I modified a washer as a spacer and used a nylon lock type nut to pull the valve closed. Allows for some adjustment of tension.

If you have some time on your hands this winter it might make a good project.

Perhaps this is some help.

Al Harpster

[sparkyj]

did you post images?

[Al Harpster]

Thanks, I thought the images posted.

Maybe I dont know how to attach!

I try again

[sparkyj]

These pictures are great. Nice work to visually lay it out. Now i see what is going on. Is there a grease one can use to help seal as well as last a while with the gas? Or perhaps that is counterintuitive to the soft metal design. :-0

[matt glascock]

Cool Otalladillon. Do they flow well? I would guess that the orifices (orifi, orificicicicices?) don't quite align as they did prior to the lapping.

[Bullfrog]

EZ Lube. It is a product used in fuel valves in small aircraft. It can be found at Aircraft Spruce (one of the major suppliers to folks who build their own aircraft).
Ed

[Bullfrog]

OOPS. I just took a look at the tube of the stuff (lifetime supply - about the size of a large toothpaste tube), it is actually EZ Turn Lubricant.
Ed

[matt glascock]

Thanks Ed. I'll score some.

[Al Harpster]

Answer to Matt's question..... after extensive lapping the fuel holes did not quite align as well as they should.

So I ran a small diameter drill thru the assembly.

You may be able to detect that the fuel hole thru the male tapered part looks a bit egg shaped as a result.

Flow was, and is, fine.

Al Harpster

[matt glascock]

Subtle, but now that you mention it, the orifice is a bit oblong. Good move. I'll give it a try.

[Bill2001]

I'd run a small drill through, too. The fuel flow doesn't need to be a lot, but at least to the full flow of the petcock.