The Muggy Weld Cast Iron Repair Kit provides everything you need to repair cracked, burnt, or contaminated cast iron quickly and permanently. Designed for both professionals and hobbyists, this kit combines 72 and 77 welding rods to deliver strong, clean, and reliable results on cast iron engine blocks, manifolds, machine bases, and other critical components.
Why Choose the Cast Iron Repair Kit
Comprehensive Solution: Includes both 72 and 77 electrodes for complete cast iron welding and repair.
Handles Any Cast Iron Condition: 72 rod anchors into burnt, contaminated, or oil-soaked castings, while 77 finishes the job with a smooth, strong, machinable overlay.
No Preheat Required: In most cases, the repair can be performed without preheating, saving time and avoiding additional stress on the casting.
Porosity-Free and Crack-Resistant: Delivers dense, durable welds with excellent ductility.
High Tensile Strength: The finished weld stretches under stress without cracking—perfect for thermal cycling applications.
Versatile Applications: Works for automotive, industrial, agricultural, and general machine repairs.
Professional Results for All Skill Levels: Whether you’re an experienced welder or new to cast iron repair, this kit simplifies the process while maintaining top-level results.
Cast Iron Repair Kit Includes
One 1/2 lb tube of 72 Electrode – Formulated to bond to burnt, contaminated, and oil-soaked cast iron.
One 1/2 lb tube of 77 Electrode – Creates a strong, porosity-free, machinable finish for clean gray cast iron.
Available in multiple diameters to suit different repair types: 3/32″, 1/8″, 5/32″
Shelf Life and Storage
Store in a dry area at room temperature. Keep rods sealed in their original packaging or an airtight rod tube to prevent moisture absorption. When stored properly, the electrodes maintain full performance and weld quality indefinitely.
How to Use the Cast Iron Repair Kit
Clean the Repair Area. Remove rust, grease, paint, and carbon buildup from the casting using a grinder or wire brush. A clean surface ensures the rods penetrate properly.
Start the Weld with 72 Electrode. Use the 72 rod to anchor into burnt, contaminated, or oil-soaked cast iron. Maintain a short arc length and make short, controlled passes. The rod’s flux coating converts surface impurities into slag and allows the alloy to fuse with the parent metal.
Control Heat and Weld Length. Avoid excessive heat. Weld one to two inches at a time and alternate sides of the crack to distribute heat evenly. Overheating can cause stress and warping.
Remove Slag Before Continuing. After each pass, chip and brush away the slag. Clean the surface before switching to the 77 rod.
Finish with 77 Electrode. Apply 77 to complete the weld. This rod produces a smooth, ductile, porosity-free finish that can stretch up to 300% more than nickel rods—resisting cracks caused by vibration or thermal expansion.
Allow Slow Cooling. Let the part cool gradually in still air. Do not quench or expose it to drafts. Natural cooling prevents stress cracking and maintains weld integrity.
Inspect and Blend. Once cooled, remove any slag and inspect your weld. Grind or blend if desired for appearance or fit. The finished repair is strong, permanent, and ready for service.
Common Applications
Repairing cracked or burnt cast iron engine blocks and manifolds.
Restoring broken machine bases, housings, or tooling.
Fixing cast iron pumps, compressors, or structural components.
Rebuilding contaminated or previously welded cast iron parts.
General cast iron maintenance and fabrication in shops or industrial environments.
What Our Customers Are Saying About the Cast Iron Repair Kit
We performed TIG on this heat register. When the customer tightened the bleeder valve, (NTP) it cracked the top portion of the heat register. We drilled and tapped a piece of cold rolled A36 and welded it to the register. Small cracks from the fracture started to show when we pressure tested, and we were able to chase the cracks and get the old register back in working order for the customer. Great product! Know where to go for cast iron repair rod! — Andrew Martin, Midwest Welding and Machine
Finally used the rod I bought from you a few years ago…GREAT stuff. I fixed a pump head that was cracked from leaving water in it before winter….a little tough to build up a thin surface with but once I got it started I could do layer upon layer. I’ll get more when I try to fix my engine block. — Ronald Hoehn
I recently purchased both your 72 & 77 welding rods and I have to say, with some hesitation. Ads never seem to be as good as they say. Well, I’m one of your converted. I’ve been working on an exhaust manifold from a 1930 Chrysler Imperial. While it took a couple of hours to make my way through the various cracks, it looks like your welding rods have done the trick. Thanks very much !! — Roger Morrow
Frequently Asked Questions
Do I need to preheat the casting?
No, preheating is not required for most repairs. For large or thick castings, preheat to around 400°F to reduce internal stress.
Why are two different rods included?
72 bonds to burnt or contaminated cast iron, while 77 creates a clean, machinable finish. Together, they provide complete repair coverage.
Can I use this kit on previously welded or brazed castings?
Yes. 72 anchors into contaminated areas, and 77 finishes with a strong, smooth surface.
Is the weld machinable?
Yes. 77 creates a machinable surface that can be drilled, tapped, or ground after cooling.
What polarity should I use?
Use DC reverse polarity (electrode positive) for best results.
The Cast Iron Repair Kit provides a complete, professional solution for repairing all types of cast iron. Use 72 to bond to burnt or contaminated areas and 77 to finish with a clean, machinable overlay.
Whether you’re working on automotive, industrial, or general machinery repairs, this cast iron repair kit delivers strong, reliable results with no preheat required. It’s the fastest, easiest way to restore cast iron components to full strength and function.
CALIFORNIA PROPOSITION 65: WARNING: This product contains chemicals including [Nickel], which are known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov
77 is a premium electrode that produces welds which are high strength, crack resistant, and porosity free when applied to a wide variety of cast irons. The special tri-metal core wire has a high current carrying capacity and the specially designed coating converts the impurities of the base metal into slag instead of being trapped in the deposit. The high deposition rate creates an extremely narrow heat affected zone– a feature suitable for all weldable cast irons requiring post weld machining.
77 cast iron welding rods are softer than nickel rods, and have unique properties that allow the cast iron welds to stretch and elongate up to 300 percent more than other rods, which helps prevent the base metal and weld from cracking in the process.
Key Features:
High efficiency weld metal transfer eliminates electrode overheating
Crack-resistant formula eliminates the need for pre-heating or special cooling
Ideal for heavy machinery, trucking, bus lines, automotive, marine, and RVs
Repair cast iron exhaust manifolds, engine blocks, industrial machines and more
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72 is a nickel-iron non-conductive electrode formulated to join dirty and contaminated cast irons. This universal electrode can be used to weld a wide variety of malleable, ductile, and nodular cast irons. In addition, it is ideally suited for the repair of defective or cracked malleable iron castings.
There are occasions in industry where exceedingly dirty cast iron is encountered. 77, which bonds well to most cast iron does have a limitation. Since 77 has controlled penetration, which is ideal for non-cracking and machinability, it may not be able to bond exceptionally dirty cast iron. 72 should be used for this application. It has a high penetration, can anchor deep into the subsurface of dirty cast iron, and seals in porosity generating contaminates prior to finish welding with 77. 72 is used for a cladding operation, then the weld is completed with 77.
Key Features:
Flux coating does not side arc even after being heated
