Cracked Block

[Dick W.]

Re: Cracked Block

Here are the videos that I watched last year, before deciding that I'd weld a crack if I had one. The procedure is VERY labor intensive, and interesting to watch:

http://www.youtube.com/watch?v=Pq0wfU4ZaKk

The process is covered in THREE videos, first for pin installation, second for lock install, and finally, the thread repair.

Putting cast iron heads in a large gas grill with the cover closed will heat the part to 700 degrees before it can be braze welded. If the crack is drilled on each end, and then v-cut before filling with bronze, it should be fine. The cooling process must be done slowly.

The heating and cooling must be done over many hours, I would prefer about 24 hours. That way it is heated/cooled though out. I have both brazed and welded cast iron, it is a very tedious job. Large castings requiring a lot of labor to remove, I would prefer pinning. A block with an internal crack will have to be removed so welding would be ok, but..... if you are not careful with that much head, you could end up with some machined surface warping

[Tom P.]

Re: Cracked Block

I have an EXCELLENT SB400 block with a crack in the lifter valley (as mentioned, those seem to be common). I'd REALLY love to save this block!!!
Would this be a good candidate for the Lock Stitch method?

[Joe C.]

Re: Cracked Block

I have an EXCELLENT SB400 block with a crack in the lifter valley (as mentioned, those seem to be common). I'd REALLY love to save this block!!!
Would this be a good candidate for the Lock Stitch method?

It looks too close to the deck. High stress area just below the deck probably puts more emphasis on the integrity of the "locks". Potential problem is IF the distance from the crack to the deck, which appears to be about 1" or slightly less, leaves enough room to use full length locks across the upper portion. Probably not, so the question is whether the use of shortened lock lengths will compromise the strength of the repair. They probably will not agree to do it, and if they do, then won't guarantee it.

I'm only guessing but wouldn't be surprised if the repair would cost you about 400 bucks. If the block is numbered for a particularly valuable car that it belongs to then I'd say it's worth having it done.

[Clem Z.]

Re: Cracked Block

It looks too close to the deck. High stress area just below the deck probably puts more emphasis on the integrity of the "locks". Potential problem is IF the distance from the crack to the deck, which appears to be about 1" or slightly less, leaves enough room to use full length locks across the upper portion. Probably not, so the question is whether the use of shortened lock lengths will compromise the strength of the repair. They probably will not agree to do it, and if they do, then won't guarantee it.

I'm only guessing but wouldn't be surprised if the repair would cost you about 400 bucks. If the block is numbered for a particularly valuable car that it belongs to the I'd say it's worth having it done.

this process is only for stuff that is expensive or irreplaceable not for run of the mill stuff.

[Joe C.]

Re: Cracked Block

this process is only for stuff that is expensive or irreplaceable not for run of the mill stuff.

I know that, and Tom probably knows that too.
I think he wants to know whether or not it's even possible.
I don't think it is.
Not enough room for the strengtheners (aka:locks)

[Clem Z.]

Re: Cracked Block

I know that, and Tom probably knows that too.
I think he wants to know whether or not it's even possible.
I don't think it is.
Not enough room for the strengtheners (aka:locks)

these 400 blocks also crack around the bottom of the cylinder bore and because of this i always "poured" the 400 blocks to strengthen them in that area if used for racing

[Joe C.]

Re: Cracked Block

these 400 blocks also crack around the bottom of the cylinder bore and because of this i always "poured" the 400 blocks to strengthen them in that area if used for racing

I agree that its a good idea to "full pour" blocks used for drag racing ONLY.
For serious street/strip use, it's a good idea to "3/4 pour" a block.
Extended running of full poured blocks will cause unacceptably high oil temps......even for full synthetic oil.

[Clem Z.]

Re: Cracked Block

I agree that its a good idea to "full pour" blocks used for drag racing ONLY.
For serious street/strip use, it's a good idea to "3/4 pour" a block.
Extended running of full poured blocks will cause unacceptably high oil temps......even for full synthetic oil.

i only poured a few inches in the bottom of the block and these were used on alky burners short track cars

[Dick W.]

Re: Cracked Block

I have an EXCELLENT SB400 block with a crack in the lifter valley (as mentioned, those seem to be common). I'd REALLY love to save this block!!!
Would this be a good candidate for the Lock Stitch method?

Tom that is a job for a good welder. Preheat, nickle rod, and slowly cool. You are in business