Author Topic: welding on cast iron  (Read 2224 times)

jacmac

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welding on cast iron
« on: November 02, 2013, 01:13:43 AM »
I have an original 71 T/A and the right exhaust manifold has a small hair line crack in it.Someone has made an effort to weld  it but it is not working.Anybody know someone who can fix it.I know its difficult to weld on cast iron.These are pretty neat looking manifolds,almost look like headers.Thanks
69 Z10,72 corvette

z28z11

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Re: welding on cast iron
« Reply #1 on: November 02, 2013, 04:03:04 AM »
Depending on what part of the country you're in, try:

Automotive Restorations, Steve Babinsky, autorestnj@aol.com, 908-236-6400 (NJ)

A&C Casting Rebuilders, Rick Geertsma, www.accastingrebuilders.com, 866-935-3227 (CA)

Casting Salvage Technologies, www.therestorationshoponline.com, 800-833-8814 (VA)

I had my damaged Z passenger side exhaust repaired years ago using the pre-heat/post weld stress relief fusion method espoused by several of these guys, with perfect results - other than a "fresh" appearance, the repair was perfect (and still is, over 20 years later). Worked for me -

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06

mickeystoys69RSSS

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Re: welding on cast iron
« Reply #2 on: November 02, 2013, 03:09:31 PM »
Thanks for the info. Good to have for future reference if I ever need it.

ZLP955

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Re: welding on cast iron
« Reply #3 on: November 02, 2013, 04:05:49 PM »
If you prepare the joint properly, use pre-heat, then weld with a high nickel content electrode, and wrap it up afterwards to cool slowly, it should be fine.
Tim - 04A VN '69 z/28 69-69 715 ex-E/MP

jacmac

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Re: welding on cast iron
« Reply #4 on: November 03, 2013, 12:01:55 AM »
Thanks for the help!!

bergy

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Re: welding on cast iron
« Reply #5 on: November 03, 2013, 01:05:52 PM »
ZLP955 - that's the way it was done at the Tonawanda foundry - not exhaust manifolds, but heads & blocks in non-stress areas.  Weld repairman would line up about 20 castings needing welding - heat the area to be welded - stick weld the repair area - immediately cover the repair with asbestos blanket - uncover it the next day - grind the repair flush.  Most commonly done on intake manifold rest area on blocks and on valve cover rail on heads.

69Z28-RS

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Re: welding on cast iron
« Reply #6 on: November 03, 2013, 07:03:42 PM »
will that process work on a block that cracked from freezing?   when I moved back to North Alabama, after being in a 'non freezing' area for a few years, I drained a radiator in a car I hadn't driven, and found out later that I should have drained the block as well..   The cracks are across both the inside (the lifter galley area about half way up), and the corresponding outside of the water jacket area.   It was a 'prepped' block, and I hated to toss it, so I kept it... hoping..   :)

Gary
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Mike S

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Re: welding on cast iron
« Reply #7 on: November 03, 2013, 10:47:48 PM »
Hi Gary,

  My one 67 BB has a 4" crack above the front right side freezeout plug. So much for freezeout plugs working.  :(
Anyhow, I drilled stopped it, cut a small depth V in it with a Dremel and filled it in with JB Weld and it has held since 1987.
But, if it starts to leak again, I read of a process to fix cast iron motor parts called 'stitching' (Lock-N-Stitch) and it looks to be a possible solution for cracks outside a block (and maybe for inside as well). It involves a lot of a repeating processes to drill, insert a special screw slug, and repeating the process while overlapping the previous screw slug until the whole crack is 'stitched' and it can be ground down to make a surface.
I just thought you may be interested to know.

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

69Z28-RS

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Re: welding on cast iron
« Reply #8 on: November 03, 2013, 11:03:54 PM »
Thanks for the note Mike,

I've seen that done (stitching)...  seems pretty remarkable... and time consuming..  :)
The welding would seem to be a less labor intensive approach, if it holds water..  :)

JohnZ

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Re: welding on cast iron
« Reply #9 on: November 04, 2013, 03:23:33 PM »
Hi Gary,

  My one 67 BB has a 4" crack above the front right side freezeout plug. So much for freezeout plugs working.  :(

That's a common misconception - those plugs have nothing to do with protecting the block from freezing - they're there to provide exit holes for the internal refractory sand cores after the cope and drag were split and dumped on the shake-out table. Any relationship between those holes and freeze protection is purely coincidental.
'69 Z/28
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Mike S

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Re: welding on cast iron
« Reply #10 on: November 04, 2013, 03:39:45 PM »
Hi John,

  The thought of a plug being pushed out by freezing water seems plausible in theory but I can see how corrosion can lock them in place. Interesting that you say this is coincidental being I have never heard them called or advertised as anything else. Oh well, live and learn.

Thanks,
Mike

bergy

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Re: welding on cast iron
« Reply #11 on: November 04, 2013, 09:13:55 PM »
" they're there to provide exit holes for the internal refractory sand cores after the cope and drag were split and dumped on the shake-out table" -

 the freeze plug holes certainly helped with sand and steel shot extraction, but the water jacket core extended out of those holes and printed into the drag mold to hold the jacket cores in proper orientation during molding & pouring.  The jacket cores were each held "up" by those "freeze plug" drag prints and "down" by 3 steel chaplets that pressed against the cope in the oil galley. Fore and aft jacket position was maintained by the water jackets printing into the housing cores.  That's why "freeze plugs" are also required at rear housing.  during solidification, water jacket cores became pretty unstable - so they had to be held in place securely.

jvb6648

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Re: welding on cast iron
« Reply #12 on: November 05, 2013, 03:41:21 AM »
Hi Gary,

I used to work for Metal Locking Service, a casting repair company. I would say that if there's room to drill a hole in the crack that it can be repaired. We've repaired heads where the crack went across the valve seat and up into the port and blocks with holes in them by putting in a new piece of iron. The repair can be ground flush so it's less noticeable. No idea on cost anymore but I would prefer it to welding. Not a DIY project.

Jim
Jim
68 Z/28

69Z28-RS

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Re: welding on cast iron
« Reply #13 on: November 05, 2013, 03:45:17 AM »
My head shop repaired a seat for me once using that technique...   *S*   was my first exposure to that approach.