Welding Cast Iron Block

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fordified
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Welding Cast Iron Block

Post by fordified » Thu Mar 08, 2018 1:44 pm

I have a Nascar block that kicked out a rod. It took a chunk of the pan rail with it. The two cylinders are ok but have a few grooves where the h beam rod hit them. Its an expensive block and has a ton of work done to it.

I want to use some cast iron square bar to fill the gap on the pan rail, weld it and then machine it flat. Is nickel 99 the way to go? I want to tig it. Also can the grooves in the bores be welded with the same rod or should I just sleeve them? The grooves are about an inch long and there are only a few of them. Id like to weld them if possible and then bore them instead of using sleeves.

Does anyone have experience doing this and any recommendations?

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Re: Welding Cast Iron Block

Post by MTENGINES » Thu Mar 08, 2018 1:56 pm

Post some pictures. Is it a 184a bowtie? Or an R5?

How far up in the cylinders.. etc. If it's low just bore the block and don't worry about it. If it's in the sweep of the rings, sleeve it.

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Re: Welding Cast Iron Block

Post by MTENGINES » Thu Mar 08, 2018 2:00 pm

Oh forgot to answer the welding part. You can use 99 rod if you preheat the block in a furnace, then use propane and a rosebud to keep the area warm. Otherwise it will crack.

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Re: Welding Cast Iron Block

Post by Keith Morganstein » Thu Mar 08, 2018 2:21 pm

I’d repair it by stitching the piece in. I don’t think I’d try and weld the cylinder bore either. As MT said if below the ring travel (and not cracked) leave the grooves. Otherwise sleeve it.

Stitching can repair all kinds of casting damage
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fordified
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Re: Welding Cast Iron Block

Post by fordified » Thu Mar 08, 2018 2:41 pm

Here are the pictures. Its a r451 ford block with small journals. 4.150 bore.

I would prefer to stitch it but worry about strength between the mains. The groove in one bore has a small hole that goes through but not to water it seems. I'll have to sleeve it and the bore across from it because they are not far enough down in the bore. I can grind off the bottom of the bore where the rod hit it and the piston will still not be hanging out.
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Re: Welding Cast Iron Block

Post by MotionMachine » Thu Mar 08, 2018 3:22 pm

If you weld there, I'd bet that it'll pull the mains out of alignment. Possibly even too much to save it.

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Re: Welding Cast Iron Block

Post by williamsmotowerx » Thu Mar 08, 2018 3:52 pm

Why do they use roller bearings for the cam journals?

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Re: Welding Cast Iron Block

Post by Ericnova » Thu Mar 08, 2018 4:30 pm

I'm thinking Silicon Bronze would be a better filler rod for the side of the block...less pull and shrinkage, won't need as much preheat, still plenty strong enough to fix what is basically just a pan rail. That area doesn't add a ton of strength to the mains, the bulkheads carry that load.

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Re: Welding Cast Iron Block

Post by BILL-C » Thu Mar 08, 2018 4:56 pm

Re-making the boss for piston oiler and redrilling the feed passage looks like fun!
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Re: Welding Cast Iron Block

Post by gnicholson » Thu Mar 08, 2018 5:31 pm

Ive had really good luck making cast iron repairs with aluminum bronze and tigging it on ac with the balance cranked up. Theres an article on welding tips and tricks about it. Actually welding cast iron is very tricky and has to be done right plus the heat involved moves everything around. I would sleeve the bore

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Re: Welding Cast Iron Block

Post by Dave Koehler » Thu Mar 08, 2018 7:06 pm

I have tigged some cast iron. Not fun but doable.
I do think that on that side piece that milling it out and stitching a piece in will be stronger than the weld without the warpage issues.
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Re: Welding Cast Iron Block

Post by peejay » Thu Mar 08, 2018 8:26 pm

I have seen someone tig together an iron block with more substantial damage, and when put back in service the engine made a lot more BMEP than any NASCAR engine could ever hope to make. (Maybe 50% more power from 25% less displacement and a whole lot less RPM)

I was not directly involved with the repair, but I do remember that the ARTIST who pieced the block back together spent a lot of time with an air hammer peening all the affected surfaces/welds.

Not a cost effective repair in the least but when you have rare irreplacable iron, you do what you have to do!

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Re: Welding Cast Iron Block

Post by fordified » Thu Mar 08, 2018 8:31 pm

Thanks for all the responses.

I'm going to see if I can stitch it but I don't know how much I can go into the bottom base metal. I'd prefer not to heat it and know that I'm going to have to align hone the mains and deck it if I do. I may not have a choice but to weld it.

It's a tough deal but I think I can save the block. Theres a bunch of new welding rods available for these kinds of repairs using minimal heat but I dont know if they are a bunch of BS or strong enough to hold up. I would heat the block to 250 degrees max. Im not going to do the 800-1000 degree deal. If I can heat the block up and run some short beads and move around I may be able to get away with it.

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Re: Welding Cast Iron Block

Post by KnightEngines » Thu Mar 08, 2018 8:39 pm

I wouldn't weld it, I'd machine/grind the mess out & make up a lump that fits & bolt it in with epoxy all over it.

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Re: Welding Cast Iron Block

Post by MadBill » Thu Mar 08, 2018 9:12 pm

Why not just build up the damaged area with a good grade of something like Plastic Steel? The pan rail is not subject to any loads of consequence and the stuff can be drilled, tapped, etc. just like pure metal.
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