360 main crack, help

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1970 La

1970 La

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Just got my block back from the machine shop and I noticed a crack in the block on the thrust main. I had them put new main studs in and alignhone it. The crack is on the inside of the main and does not look like it is cracked to the bolt hole. Is this a comon problem on a small block?
Can post pics if wanted thanks.
 
You need a new machine shop AND a new block.
 
Any crack is bad.Don't know where Princeton is but I have a bunch of 360's
 
Not good.... I would assume the torque from the stud will make that spot rise and put pressure on that part of the bearing...thus making the bearing wear...thus creating a leak....

Am I wrong?

Your machine shop should have caught that......

Am I wrong?
 
I have never in my life seen that. Usually it is down on the thrust side going into the main webbing. I will be damned if I would use that. It's certainly not gonna get better.
 
mbaird said:
Not good.... I would assume the torque from the stud will make that spot rise and put pressure on that part of the bearing...thus making the bearing wear...thus creating a leak....

Am I wrong?

Your machine shop should have caught that......

Am I wrong?
Click to expand...

Exactly. You cannot expect the machine shop to provide you another block, but they SHOULD do all the work again to another block. Free. I'm not sure I would let them.
 
My I phone realy makes it so you can see it. Right in the middle of the hole makes me wonder if there was oil in it and it was tightened.

I did not have him mag the block. This guy has built some real horsepower out of the small block mopar. He has a w2 headed sprint car. Maybe he just getting older and dont give a **** I dont know.

Hey Donnie I have several 360 blocks. I am the guy that got all the dodge pick up stuff from you. Going together with it now. Its going to make a real nice truck for my boy.
 
I wonder if the shop bottom tapped those holes.? I bet not! If that stud is tight I bet there is **** in the bottom of the hole and when they torqued the mains for line hone it cracked!
That is my thoughts anyway.
 
I pulled the stud and there was plenty of room under the stud but may not have been when he first tightened it. Realy sucks it is a 71 block.
 
Anybody can make a mistake.....show them the pic and ask them what they can do for you... Be polite! I am sure they will be horrified and take care of you if they are a quality shop..
 
My painter just finished my Cuda that I did all the prep work on.
It looked incredible except for some pinholes (alot in 2sections) that both of us missed... He said he could not beleive that they didnt notice them and would redo it...

It was my fault !
 
1970 La said:
I pulled the stud and there was plenty of room under the stud but may not have been when he first tightened it. Realy sucks it is a 71 block.
Click to expand...

Another scenario would be that the shoulder of the stud bottomed out and then it spun as it was torqued causing the crack. I wonder I'd he used oil or the arp lube?
 
Yeah I'll give him a call tomorrow.

Years ago I took a 400 mopar a part and there was cracks on the mains in several places dont remember were at for sure but I am thinking it was the same place. Later I talked to another guy that had seen the same thing on the 400. My first on the small block.
 
You MO boys must be hard on motors.... Or need to buy better torque wrenches...lol
 
If its cracked from the hole over to the saddle...maybe something hit the stud hard and close to the saddle.

To screw them in so hard as to force hyd lock cracking should have been a sign...but if they had their apprentice/kid in there learning like this shop in Fresno did who pressed dowl pins into wron holes on the deck of a 89 roller block, forgot to line hone but charged for it, put wrong valve size in and then attempted to correct it but forgot to actually grind the seats for the 2.02 they slid in, crooked cam bearings, ugh...AUTO MACHINE SPECIALTIES ...They also couldnt get the concept of stem heights vs shaft rocker gear...Chevy lovers, all kinds of shop, pricey machines, imaging,CNC etc...all worthless when coupled with lame operators/machinists
 
it's not an area i've seen crack before but:

"I did not have him mag the block."

There's your answer. I would not use that block at all. This is why the few hundred bucks to mag everything is worth it.
 
Thought i recognized
The avatar.hate to hear about the block.ill check mine but i dont think they are that old
 
d5667 said:
Thought i recognized
The avatar.hate to hear about the block.ill check mine but i dont think they are that old
Click to expand...
don`t know about the small blocks, but the main studs on a big block are only supposed to be finger tight. same thing recommended on 406 sbcby gumpy jenkins just sayin----bob:toothy7:
 
They were just finger tight. Some one had mentioned maybe the stud had been hit against something makes me wonder.
 
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