I don't know why guys say jb weld wont work. we ran a junk 400 block all season(circle burner) with a crack in the lifter galley where it had frozen(we didn't know it when we peiced it together until we filledit and could hear water running into the oil pan) tepaired by jb weld. track champions by a long shot.
Ni rod and a Lincoln welder is your best bet. it is not something that is hard to do and unless you have a line on 25 or 30 dollar blocks it is going to be your cheapest solution.
Ditto, Small block Chevy blocks of any size are too easy to come up with to want to spend the time and effort to try to save. As Jim said, the only ones a guy might want to put the effort in are ones that have some rare code or may be the key to keeping a 100% restoration 100% matching numbers. The only other reason to try and save it is that if it has already had lots of dollars spent on machine work. Usually that crack is due to neglect as in the last guy who had it didn't think enough of it to put antifreeze in it.
I was having my 272 yblock bored to 292 when the machinist noticed a crack in the same place as yours. He sent me & my block to a welder that said he could weld it and it should be OK. Not running yet so I'm keeping my fingers crossed.
I went back and read though the thread again. If it's cracked on the outside are you sure it isn't cracked on the inside of the waterjacket? 20 something years ago I had a student pull a Mopar of some kind with a 440 in it in the shop because it didn't have antifreeze or enough of it and the block froze. He drug it in on Friday afternoon and we left for the weekend. On Monday there was a lake of oil and water under and around the car because the block had cracked on the inside and the ice/water melted and filled the oil pan until it pushed the oil out the breather. If you weld it yourself all you will be out is time and the cost of the welding rod. If it doesn't work 400 blocks aren't that hard to find.
The oil pan was clean and had no water in it so I am going to assume that it didn't do any damage internally.
How much is it worth to you ? you can buy another block for what you'll pay to weld it. Will someone that welds cast iron guarantee it, i doubt it. 50/50 crapshoot at best. you would be better off gambling on an over the counter block sealer. I've sealed only one and i used waterglass (sodium silicate) .
JB weld is indeed just a glue, but it does work. The cost of trying it is minimal and the block does not have to come apart. You can improve on my original post by screwing a small steel plate over the hole while doing the JB weld process. After it is done and dried fill the system and pressure check the system. If it holds pressure for several hours then chances are its fixed. The radical ideas here are said by folks with deeper pockets that me. Cheep is good.
I've seen JB weld held down by a bar between the two freeze plugs - they just drilled into steel freeze plugs and put stainless bolts through them from the engine side, and used the threads to hold a patch tight to the crack. It still weeped a little but there was NO prep other than spray the crack with carb cleaner and hope for the best. So, give it a try, not much to lose; if it fails then you can find another block or get it stitch welded.
Why couldn't it be brazed? As for JB weld, I think if there isn't much pressure on it, it would work because I once bought an inboard/outboard boat that I ran for a couple of years before I discovered about a 4 inch long crack had been JB welded on it. Had it a couple of more years before I sold it. It never had a problem, but marine engines are not cooled with pressurized water so that may have made a difference.
This is what I did , First I drilled a hole at each end Then I taped each hole 5/16 fine threads . I Vd the crack a little & used JB weld . Then I made a 1/4 in thick aluminum plate & gasket with silicone about 1 1/4 in wide & bolted it to block , No leak
if you have any skills at all you can fix for cost of the cast iron plugs drills and a tap cheap only takes time...........
Had a 56-265 corvette engine stiched in the same spot last year.It has held up water tight.Cost was about $300.Pretty pricey but it was a numbers matching original engine.
since it seems to be a external crack just drill a series of holes starting in the ends along the crack and braze it up. having someone with propane torch heating area during the brazing proccess helps the flow of the braze. i fixed a 235 head 30 years ago and the engine is still in vehicle running strong.
Check with your local machine shop, they can do a stitch lock repair. The stitch lock repair replaced the old irontite repairs. I have a flat head with repairs through two valve seats! seated the valves right on top of them did not replace seats.Go to stitchlock .com they are used all through industry. Tony