Thread: cracked exhaust manifold

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Possibly dumb question time:

Can a cracked cast iron exhaust manifold be satisfactorily welded, then surface ground to eliminate possible warpage? Or should I head for Little John's wrecking yard ..... again.

The part is the driver side manifold from a 500 c.i. Cadillac.

Thanks,
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Big Tracks

My brother fixed a crack in the exhaust manifild of his boat with JB Weld. It lasted for 4 years and holding when he sold it. Personally I would replace it if one was readily available and you had to pull the old one off to fix it anyway.

Pat

Pat

The welding and surface grinding would probably cost more than a used exhaust manifold. With everybody putting headers on BBC's there has got to be a ton or two of them laying around in shop corners......

i have some luck welding with a nickel rod with stick welder i would bolt it down to a old head V it out but not to much and the rod i used is made by weld mold in mich i think at 700 rod .if you can not fined if it let me know i will get the numer for it. weld a bit and pein it with a hammer.do not try to weld it all and keep the amps down and clean the flux out good . weld no more than a 3/8 at a time i have good luck with out pre heat do not V out to much and do not go thur the manifold the more you take out the more it will want to pull and make it crack with this rod i have weld ears on blocks and heads and it is good to machine this rod is the stuff to use

they do make rods for cast iron , your local welding supply should point you in the right direction. the only drawback is to properly weld cast is to preheat the part to like 800 degrees, then weld , then slowly cool the part over a day or so . I`ve done a head this way , it worked good. We put the head in a standard oven on broil for like four hours until we got thetemp we wanted

Also like pat said a nickel / copper -nickel alloy will also be machineable a mild steel rod with a special flux won`t hope this helps

Thanks, Pat, Dave, Pat again, and Hotroddaddy,

I apprecciate your input. I'm looking for another manifold and am not having any luck yet, but then I haven't had time to do much scrounging. I'm sure you're right, Dave, repairing the cracked one probably wouldn't be smart from a money standpoint.

I'm not a welder (and I can prove it!) but I know a couple of guys who are. There are several welder supply companies around here so I'm sure I can get the right rods.

I had a 383 in an old ('72) Dodge pickup. Somebody back down the line had brazed a crack on one manifold. It was holding when I sold the truck, but I was never convinced that that was the way to go.

Anyway, thanks again, gentlemen,

Big Tracks

Originally posted by Dave Severson
With everybody putting headers on BBC's there has got to be a ton or two of them laying around in shop corners......

GOOD LUCK finding a good one(they are out there), both manifolds on my caddy were cracked & i have yet to find any at the bone yards around me that were good. hell why do ya think everybodies putting headers on caddy mtrs, cause u cant buy BUT one new manifold the other side isnt made.....joe

There are four listings on EGAY right now for Cad exhaust manifolds...not sure if they fit yours.

brazing works ok but it does not bond the metal , it kinda glues it . If you know a couple of welders they should be able to pull it off fairly easy, and the rods should be cheap ,less than new manifolds