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Welding Cast Iron


Mike, I have to tell you that your 77 cast iron electrodes are fantastic--I need to order more to have it on hand.


I just welded a small block Chevy 400 engine with a broken ear on the starter mount. The engine was sitting on a 3 wheel engine stand and fell over breaking the mount. I placed a mild steel bolt in the broken mounting hole and built the whole corner back up, then I removed the bolt and re-tapped the bolt hole with no problem. It's looking pretty good.


I work on hard to find and restore irreplaceable antique cast iron parts. Your 77 welding rods are better than anything I've tried in the past. I'll try to remember to send you photos of my next cast iron job.


- Bob Carpenter
Ephrata, WA
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Cast Iron Welding

Cast iron is strong, wear-resistant, and inexpensive. Because it's an extremely versatile material, this metal is used in literally thousands of industrial products. Therefore, welding cast iron is an essential process that welders and craftsmen in the industry must learn. Despite the brittle and temperamental qualities of cast iron, welding it is not impossible to do, provided that you have the right materials on hand. 


Cast iron is difficult to work on because most nickel rods used by welders are harder compared to the base metal. Welding cast iron increases the base metal's tendency to crack, just like how a window with a rock cooled in the center is more likely to shatter into pieces. However, our electrodes possess a different metallurgical makeup—they are softer, highly machinable, and have unique properties that allow the weld to stretch and elongate up to 300 percent more than other rods. This helps prevents the base metal and weld from cracking in the process.  


  77 Electrode 72 Electrode SSF-6 Silver Solder
Sizes available 5/32", 3/32", 1/8" 5/32", 3/32", 1/8" 1/16"
Arc - TIG - Braze Arc - TIG Arc - TIG Braze
Works on engine blocks Yes No Yes
Works on large cast iron holes Yes Yes No
Joins cast iron to steel Yes Yes Yes
Joins cast iron to metals other than steel No No Yes
Works on exhaust manifolds, woodstoves, or other burnt cast iron Good Great Good
Works on thin cast iron Yes Yes Yes, even very thin
Color match? Fair Fair Fair
All position? Yes Yes Yes
Machineable? Yes No Yes
Paintable? Yes Yes Yes
Works over existing welds? Fair-- better on unwelded surface Fair Great
Depth to bevel cracks 3/4 through 3/4 through 1/2 way through
Crack resistant? Yes No No


Make welding cast iron a breeze with high quality products from us here at Muggy Weld. For more information on cast iron repair, and to watch instructional videos, click the links below

Cast Iron Welding Videos

Cast Iron Welding a Stover Pump BaseNew!

Muggy Weld customer Herman Ginger Herman, a self-described "novice" welder, welds a cast iron Stover Pump Base with 77 arc rods and a Miller AC/DC 225 amp welder.

1986 580 E Case Backhoe RepairNew!

Muggy Weld customer Richard Nicholas Jr. repairs the front axle on a 1986 580 E Case backhoe, using 77 cast iron electrode and an AC arc welder . The king pin bearings were gone, and the pins had worn into the axle.

Crack Free Cast Iron Welding New!

Whether you're working with gray cast iron, malleable cast iron, or nodular cast iron, Muggy Weld 77 electrode can make the repair--simply, quickly, and without pre-heating or special cooling procedures.

Silver Soldering a Cast Iron Flange to Aluminized Steel Tubing for RX 7

Josh Colson from Auburn Muffler and Auto Repair in Auburn, Washington, is using SSF-6 Silver Solder by MuggyWeld.com, to braze a cast iron flange to aluminized steel tubing for better air flow.

Cast Iron Welding: How to Weld a Cast Iron Engine Block

1989 Continental Diesel Cast Iron Engine Block with a sizable hole punched through from a rod was welded with MuggyWeld 77 Cast Iron electrodes. Our customer used TIG welding for this motor, but many of these engines have been repaired using arc or stick, even with an old buzzbox.

Welding a Jeep Wrangler Engine Block with 77 Cast Iron Electrode

Muggy Weld customer Mike Timm welded his 2004 Jeep Wrangler engine block, which had a piston skirt blow a hole in the side of the motor.

Cast Iron Welding: Cummins Diesel Cast Iron Exhaust Manifold Repair

Second repair on Cummins exhaust manifold. Mike used a 130 amp mini welder to make the repair, to demonstrate a worst case scenario for using our electrodes.

Cast Iron Welding: Cast Iron Exhaust Manifold Repair

A cast iron exhaust manifold is brazed with SSF-6 Silver Solder. We cleaned a 3 to 4 inch cut, then silver soldered the cut with an oxyacetylene torch.

Cast Iron Welding: Cast Iron Fireplace Stand Repair

This fireplace stand had a broken-off leg, so we wire wheeled the paint off and used our 77 electrode with a 130 amp mini welder to make the repair.

Cast Iron Welding: Cast Iron Diesel Marine Blower is Repaired with 77 Electrode

This blower has a large cut into the cast iron. We used a grinding wheel to bevel halfway through, and made the repair with our 77 cast iron rod and a 130 mini amp welder. After making the repair we used a grinding wheel to smooth the surface, and the part was as good as new.

Cast Iron Welding Articles

Cast Iron Welding

1989 Continental cast iron diesel block is welded with Muggy Weld 77


Cast Iron Welding: Cast Iron Tractor Welding

John Deere JD450 Dozer, tractor - skidder is welded with Muggy Weld SSF-6 Silver Solder.


Cast Iron Water Pump Repair

Lincoln cast iron water pump being welded with 77 electrode.


Cast Iron Exhaust Manifold Repair

Cummins cast iron exhaust manifold is welded with 77 and 72 rod.


Cast Iron Exhaust Manifold Torch Repair

Cast iron exhaust manifold with a large crack is repaired with an oxyacetylene torch and SSF-6 Silver Solder.


Cast Iron Tractor Engine Welding

Cast iron CASE engine block with a 15 inch crack and large hole is welded with 77 electrode.


Cast Iron Engine Block Welding

A thrown rod resulted in a quarter inch hole in this engine block. The repair is accomplished using 77 electrode and a small buzzbox.


Cast Iron Welding

A Muggy Weld customer blog post of how to repair dreaded 53 Cummins engine blocks.