Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the weld.
Should I just vee it out completely to the outside and build up with beads?

On Mon, 01 Sep 2014 12:46:49 -0600, L Fisk wrote:

Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the
weld.
Should I just vee it out completely to the outside and build up with
beads?

Is the tab broken all the way off, or is there meat all the way around
that you can weld onto?

I can't comment on stainless vs. nickel, other than to note that you
already know how to use nickel so why not stick with what you know?

I'm not sure that you're headed for happy-ville here anyway -- I would
expect that if you want something better than "hold it together long
enough to sell" you need to strip the thing down to a bare block, weld
it, then re-machine any mating surfaces that are close by (which is
presumably the bellhousing: I can't visualize a SB chevy well enough to
know if you'll be getting into the oil pan mating surface).

Is it something too rare and special for you to just get another block?

--
www.wescottdesign.com

tim wrote:
On Mon, 01 Sep 2014 12:46:49 -0600, L Fisk wrote:

Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of
the weld.
Should I just vee it out completely to the outside and build up with
beads?

Is the tab broken all the way off, or is there meat all the way around
that you can weld onto?

I can't comment on stainless vs. nickel, other than to note that you
already know how to use nickel so why not stick with what you know?

I'm not sure that you're headed for happy-ville here anyway -- I would
expect that if you want something better than "hold it together long
enough to sell" you need to strip the thing down to a bare block, weld
it, then re-machine any mating surfaces that are close by (which is
presumably the bellhousing: I can't visualize a SB chevy well enough
to know if you'll be getting into the oil pan mating surface).

Is it something too rare and special for you to just get another
block?

The problem is that his weld will be hot , The thermal mass of the block
will keep the tab quite low . When the weld cools it's going to pull away
from the cast - no matter what he welds with . The only way I can see
getting around that is to weld short beads parallel to the length of the
hole and let them cool thoroughly before doing the next . And I use braxing
rod , and only fill it enough to use a permanent insert timesert ? because
the brass filler probably won't hold a thread for long .
And I can visualize that block , is it the upper or lower hole ? Lower has
a higher chance of success IMO . Hmm , almost has to be the upper , doesn't
the bolt come from the rear on the lower ?

--
Snag

On Mon, 1 Sep 2014 12:46:49 -0600, "L Fisk" wrote:

Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the weld.
Should I just vee it out completely to the outside and build up with beads?

Why not weld in an insert?

Gunner

"At the core of liberalism is the spoiled child,
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosophy of sniveling brats."
PJ O'Rourke

On Mon, 1 Sep 2014 12:46:49 -0600, "L Fisk" wrote:

Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the weld.
Should I just vee it out completely to the outside and build up with beads?

You could also Braze in an insert..which is what Ive done before.


"At the core of liberalism is the spoiled child,
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosophy of sniveling brats."
PJ O'Rourke

"L Fisk" wrote in message
...
Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.

It looks like this pic
http://www.carcraft.com/techarticles...photo_01.html#

except mine is wallowed out larger till there is not much meat around the
end at all
think I'm best to weld it up solid and drill/tap a new hole
I know about preheating and peening the weld on cast
If there were any threads left I would thread a peice of carbon and weld
around that
I have the block out and stripped bare, so now it the time
might find a new block for around $500
but this one is good except that little problem
thanks for all the quick replies :-)

On Mon, 1 Sep 2014 15:37:22 -0600, "L Fisk" wrote:


"L Fisk" wrote in message
...
Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.

It looks like this pic
http://www.carcraft.com/techarticles...photo_01.html#

except mine is wallowed out larger till there is not much meat around the
end at all
think I'm best to weld it up solid and drill/tap a new hole
I know about preheating and peening the weld on cast
If there were any threads left I would thread a peice of carbon and weld
around that
I have the block out and stripped bare, so now it the time
might find a new block for around $500
but this one is good except that little problem
thanks for all the quick replies :-)
Last week I needed to repair a transom clamp on a Johnson outboard.
The original 5/8-11 threaded hole was stripped and there wasn't enough
material for even a Heli-Coil insert. So I tapped the hole 3/4-16 but
used a drill much larger, relatively, than the normal minor diameter
of the thread. I then made an insert on the lathe tapped 5/8-11 and
threaded 3/4-16 on the OD. The 3/4-16 thread was really only about 50%
because I made the minor diameter only .003" smaller than the hole I
drilled in the transom clamp. To do this I set the compound on the
lathe parallel with the Z axis. Then after single point threading
until I got to the minor diameter I wanted I used the compound to
advance the treading tool .002" per pass and widened the thread until
the pitch diameter was correct. So the insert ended up with shallow
threads with a really wide root. Finally the insert was installed with
Loctite so that any clearance between the insert and the part was
filled. I made the insert from stainless because it was for an
outboard motor. In your case I would use any easily machinable steel
you have laying around. Ledloy would be plenty strong enough. 303 SS
would be a good choice as well as 17-4 or 15-5 SS. Though the PH
stainless steels are not that easy to machine they do finish nicely. I
would not use mild steel because it tears so easily.
Eric

L Fisk wrote:
Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the weld.
Should I just vee it out completely to the outside and build up with beads?


I would bore out the hole then install a long solid wall insert. Then V
out the cracks and braze them up. The insert will extend the grip into
the better iron. The brass will stabilize it.

--
Steve W.

On Mon, 1 Sep 2014 12:46:49 -0600, "L Fisk" wrote:

Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the weld.
Should I just vee it out completely to the outside and build up with beads?

I might comment that I once welded a cast iron cylinder head using TIG
and probably 308 rods and the weld was hard enough to take the end off
a HS end mill. If you will need to machine the repair it might be
something to think about.
--
Cheers,

John B.

"John B. Slocomb" wrote in message
On Mon, 1 Sep 2014 12:46:49 -0600, "L Fisk"
wrote:

Need to weld a broken starter mount tab (outside
hole)
on a SBC block. Hole is way beyond using a
thread insert
Fairly experienced at arc welding cast with
nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig
wire
instead of nickel arc rod.
If I just weld the hole shut the new threads
will cut away most of the weld.
Should I just vee it out completely to the
outside and build up with beads?

I might comment that I once welded a cast iron
cylinder head using TIG
and probably 308 rods and the weld was hard
enough to take the end off
a HS end mill. If you will need to machine the
repair it might be
something to think about.
--
Cheers,

John B.

Isn't NI 55 considered non-machinable? It's been
my
experience that it is not...
pdk

" I might comment that I once welded a cast iron
cylinder head using TIG
and probably 308 rods and the weld was hard enough to take the end off
a HS end mill. If you will need to machine the repair it might be
something to think about.
--
Cheers,

John B.

Isn't NI 55 considered non-machinable? It's been my
experience that it is not...

I will use good (expensive) nickel 99 rod, think I still have some UTP
I think around 55,000 PSI tensile strength
it machines well should make stronger threads than the cast iron by far as
I have at least an inch of thread length.
will preheat, peen, and cool it slowly wrapped in insulation of some kind
You guys have helped me tackle this with more confidence
thanks everyone.

On Mon, 1 Sep 2014 19:18:34 -0600, "L Fisk" wrote:


" I might comment that I once welded a cast iron
cylinder head using TIG
and probably 308 rods and the weld was hard enough to take the end off
a HS end mill. If you will need to machine the repair it might be
something to think about.
--
Cheers,

John B.

Isn't NI 55 considered non-machinable? It's been my
experience that it is not...

I will use good (expensive) nickel 99 rod, think I still have some UTP
I think around 55,000 PSI tensile strength
it machines well should make stronger threads than the cast iron by far as
I have at least an inch of thread length.
will preheat, peen, and cool it slowly wrapped in insulation of some kind
You guys have helped me tackle this with more confidence
thanks everyone.
Is this a valuable vehicle with a numbers matching block or
something?? What version of SBC? Surely canot be that hard to find a
bare block since you already have the old one stripped. Personally I
wouldn't waste the effort fixing the damaged block.

L Fisk wrote:

" I might comment that I once welded a cast iron
cylinder head using TIG
and probably 308 rods and the weld was hard enough to take the end off
a HS end mill. If you will need to machine the repair it might be
something to think about.
--
Cheers,

John B.

Isn't NI 55 considered non-machinable? It's been my
experience that it is not...

I will use good (expensive) nickel 99 rod, think I still have some UTP
I think around 55,000 PSI tensile strength
it machines well should make stronger threads than the cast iron by far as
I have at least an inch of thread length.
will preheat, peen, and cool it slowly wrapped in insulation of some kind
You guys have helped me tackle this with more confidence
thanks everyone.


http://www.mcmaster.com/#standard-th...nserts/=tjhdyi

L Fisk wrote:
Need to weld a broken starter mount tab (outside hole)
on a SBC block. Hole is way beyond using a thread insert
Fairly experienced at arc welding cast with nickel rod
but also have a mig welder.
Some folks have suggested using stainless mig wire
instead of nickel arc rod.
If I just weld the hole shut the new threads will cut away most of the
weld.
Should I just vee it out completely to the outside and build up with beads?




http://www.mcmaster.com/#standard-th...nserts/=tjhdyi