[Public-List] Manifold petcock Atomic 4

Sun May 20 05:00:20 PDT 2012

Thanks Kris
Problem is that the hole is so shallow (maybe 1/2inch) that the tappered tap bottoms out before it can begin to cut. I started the engine yesterday and held my finger over the hole. Almost no pressure so it wouldn't take much to plug it. 
Ron #292

--- On Sat, 5/19/12, Kris Coward <kris at melon.org> wrote:

> From: Kris Coward <kris at melon.org>
> Subject: Re: [Public-List] Manifold petcock Atomic 4
> To: "Alberg 30 Public List -- open to all" <public-list at lists.alberg30.org>
> Date: Saturday, May 19, 2012, 11:30 AM
> 
> A bottoming tap is intended to be used _after_ a regular
> tapered tap;
> going straight to a bottoming tap can lead to uneven threads
> (because
> the bottoming tap doesn't have enough of a thread to bite on
> at the
> beginning of the hole), or even shards of broken tap left in
> the hole
> (taps are hard and therefore brittle; if one has to cut too
> much
> thread at once, the stress can crack it, and then it'll need
> to be
> ground out). It may be less of a concern when cutting a
> softer metal
> like brass out of an existing thread, but I've damaged
> enough threaded
> holes (and ground out enough tool shards) that I wouldn't
> hesitate to
> get and use both taps just to be on the safe side.
> 
> Cheers,
> Kris
> 
> On Sat, May 19, 2012 at 09:40:37AM -0400, Don Campbell
> wrote:
> > If you can find a bottoming tap of the correct size, it
> has far less
> > taper than the normal tapered tap. You might want to
> compare it with
> > a plug tap to see which might suit you best. I imagine
> you will have
> > to go to an industrial supplier who carries an open
> line of tools to
> > find them.
> > Don #528
> > 
> > On 5/19/2012 8:27 AM, Ronald Walker wrote:
> > >The engine is the old Atomic-4.Its my understanding
> that all Albergs were originally powered by them.I believe
> the petcock is brass and the manifold is some type of steel.
> As I said the threads are there, just flattened out. I'm
> going to try some J.B.Weld. Don't know what else to do.
> > >
> > >--- On Sat, 5/19/12, Glennb<brooks.glenn at comcast.net> 
> wrote:
> > >
> > >>From: Glennb<brooks.glenn at comcast.net>
> > >>Subject: Re: [Public-List] Manifold petcock
> Atomic 4
> > >>To: "Alberg 30 Public List -- open to
> all"<public-list at lists.alberg30.org>
> > >>Date: Saturday, May 19, 2012, 1:18 AM
> > >>What kind of engine/manifold do you
> > >>have, and what material is the petcock made
> of?  sounds
> > >>like the petcock corroded off, leaving part of
> the threaded
> > >>portion in the manifold.
> > >>
> > >>If so, try going in with a very small drill
> bit, maybe
> > >>slightly larger than the ID of the hole, then
> run a series
> > >>of increasingly larger taps to ream out the old
> material to
> > >>match the original ID and thread.
> > >>
> > >>just did this on my steam engine, took about an
> hour to
> > >>replace the broken nipple. But it was brass and
> the boiler
> > >>is steel.
> > >>
> > >>Glenn p
> > >>dolce 318
> > >>
> > >>
> > >>Sent from my iPad
> > >>
> > >>On May 18, 2012, at 12:47 PM, Ronald
> Walker<rwpsw at sbcglobal.net>
> > >>wrote:
> > >>
> > >>>Maybe someone can help me with a small
> problem I
> > >>discovered during the spring start-up
> procedure.On the aft
> > >>part of the manifold there is a petcock. Its is
> for draining
> > >>the manifold water jacket. As I began to close
> the petcock I
> > >>noticed it was loose. I tried to tighten it but
> it ended up
> > >>falling off in my hand. After a good close look
> I saw that
> > >>the threads were all buggered up.On the petcock
> as well as
> > >>the hole. I thought about running a tap in to
> maybe sweeten
> > >>up the threads but the recess is way to
> shallow. Any advise
> > >>would be appreciated.
> >
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> -- 
> Kris Coward       
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