Hard to tell in the pic but if that crack goes to the soft plug hole, the stitch method may not work.

Thats the way I would try first.. stitch first then weld if needed

I tried using block filler to stop water jackets leaks on a customers old Mopar cast iron top fuel block that had interior coolant leaks from grinding for clearances around the mains from a different owner.
I ended up having to use a liquid block sealer from Goodson that had to be pour into the block and then sealed up under pressure with a torque plate and water pump block off plates for 20 minutes and then baked in a oven at around 350 F for 20+ minutes after draining the sealer out of both sides one side at a time. It was reusable and it did a good job on fixing those coolant leaks. I did both sides first and then had the block cooked by a local powder coating shop, we pressure checked it at 30 Lbs. for 20 minutes before putting it back together.
The customer put that motor in a car and it is still running today as far as I know

Had a crack like that from a block left outside in a car,purchase some KW block seal and that stuff seal that crack up right before my eyes ran that block for another 14 years before replacing it.

Disclaimer: I have never personally done this but I know of two individuals that have welded cast iron blocks with this stuff.

Cast Iron Welding Rod

hi

i have a friend that has a 440 block with a crack just like those !

it is actuau a 493 cu stroker .

we sealed it with a external epoxy .

if you pm me i will get the brand .

we cleaned the block paint off with a die grinder with wire brush , then hand scoured it with 60 grit sand paper .

put pressed epoxy on firmly and let it cure .

no more leaks ! 2 years + .

his crack extended to the freeze plug hole .

he races the car 6 - 8 times a year . <street car>

We are just south of Pittsburgh and we weld blocks and other cast parts

Sounds like silver solder, what’s used in home AC systems. Makes a strong joint

I witnessed my boss fix an exact crack as the op in his buddies freshly built 383 in a rr. Moroso a b epoxy, was still good yrs later when his buddy sold it.

If all went well with no other cracks what would a weld up cost for a job like this, just ballpark.

wrong post

Try Lock-n-Stitch as you can do it yourself.

I have used this product on my 440 when two cracks popped up in the water jackets. Cost at the time was around $100-$150 all in if I remember correctly. Knock on wood, but mine has been fine since fixing it around 8 yrs ago and I got a stout piece that puts out about 580HP.

^^^^^^this^^^^^^^^^^^^ done it several times without a single failure. One I did in 2006 is still running, and never leaked a drop. Irontite plugs.

Usually $500+/- it all depends on the block condition and process