I bought a 350 from the junkyard about 3 months ago, it was rebuilt with +.040 pistons and -.010" crank. I was just going to replace all the bearings and re-ring it. The block it a 4 bolt 3970010 block from a 73 truck. I was cleaning the bare block yesterday and noticed a crack in the lifter valley. My question is can this be be repaired? Welded or JB weld. I know the correct thing to do is junk it and get a new block. But will it work, i was going to get a new block for a 383 later.

Thanks

 

Another

 

Dunno, I'm no expert on engines. I know that some can be welded. The cracks I found on my block couldn't be welded. Cracks between 3&5, and 4&6 on the water jackets. Basically the block was gone. And I wouldn't trust it even if I COULD have someone weld it.

 

yeah it can be welded, but then again almost anything made of metal can be. it's common to have cracks there, head bolts stress the block in that area. if i were to weld it i'd grind the crack till it was completely removed or i hit water. my first choice would be steel mig, second choice would be nickel tig. considering how easy blocks are to come by i'd trash it and start over.

 

Is it just me or does it look like there was already some work done in that area just below it?

 

I think thats an optical illusion. It doesn't really look like work has been performed. The crack go through into the water jacket.

 

for what it costs to weld it, just junk it and get another. You will not have any peace of mind. To do it right, the whole block must be preheated, and you will need a skilled welder. I can't see it being cheaper than a new block.

 

Alright what motor should i look for, what vechicles cam with them? 4-bolt? Cheap short-blocks? What should i do?

Thanks, I really wanted to have this motor running by march!!

 

I just went through the same thing, cept I didn't have a cracked block. If your set on 4 bolt mains, concider a 2 bolt block and have milodon caps installed. I talked with several dirt trackers and machinests, and they said they prefer 2 bolt blocks with the 4 bolt caps installed. I'm using a 4 bolt block for my 383, but they told me, for under 7000 rpm a 2 bolt would be just fine. As for the block you have at the moment, I wouldn't use it. Most pick up trucks had 4 bolt blocks. My brother just bought a 74 chevy 3/4 ton with a 400 4bolt for 150.00 running.

 

again i'd replace it, but if i were to weld it i wouldn't worry about preheating the block like someone said to do. i might set it in front of a heater and get it up to 150 or so if i were using tig. actually with steel mig you ought to just about be able to lay your hand on it after you make a pass. it isn't hard to weld, blocks and heads are made of fairly good quality castings, not like water pumps or manifolds. i've done a fair number of heads cracked between the valves with no problems and heads are a lot more complicated than a block.

 

Yeah, they had a guy weld a block on Crank and Chrome a couple months back and they could touch it with their bare hands right after he was done. The trick is to have guy who knows how to do it with low temperatures. That guy was an instructor from one of the welding manufacturers, so he really knew his stuff. Didn't take him very long either, maybe a few minutes.

 

Personally I would try and save it. Those 010 blocks have a high nickle or tin content, can't remember which. They do not show up very often.