I have STD Bore 1978 year 400 block to stroker build and now checked cylinder walls and number 1 cylinder has thin spot on about middle of bore maybe bit below on lifter walley side. Its about 11 a clock if you watch from drivers side of block. Thickness there was just about 0.100 but if i move to 9 a clock or 1 a clock there is about 0.180-0.190. Also If i go down from that Area about inch there is about 0.200 and up ab inch its about 0.160. Other bores was fine to go. What i should do? Fill it up with hard block to Waters pump holes? Sleeve that one cylinder? Its quite hard to find blocks from Finland and they are quite pricy and those can be even worse. Engine will see street mostly about 90% of time.
400 block number 1 cylinder thin area.
- Thread starter J.V
- Start date
-
74 360 dart sport
Well-Known Member
Did you have it sonic tested before you bored it
Its not bored yet.
33IMP
Well-Known Member
Considering your access to parts in Finland, and the probable costs associated with a build of this type there, IF you have a competent machine shop available, and IF you can get a sleeve, I would certainly put a sleeve in it.
Here, a person might hunt a different block. Where you are, a sleeve is the best answer.
Here, a person might hunt a different block. Where you are, a sleeve is the best answer.
EchoSixMike
Well-Known Member
Sleeve it. S/F....Ken M
I agree. If your results are accurate, sleeve it. That's way too thin.
Yeah results are accurate. Block was checked with two different machines. Other sonic tester was industrial level machine that costs over 10K and my own cheap tester measured same results within 0.1mm. i have contacted to machine shop already and guy there makes all kinds of special stuff and lots of race engines. He had few different sleeves there including ductile ones but if ductile ones would be installer then every hole needs ductile sleeve because thermal expansion is so different compared to cast iron. That also would cost about 7000$ so not worth for stock block. Machinist also told that If i fill my block with hard block it should live because thin area is quite small and so low on bore. I personally think sleeve would be better.
Not wanting to be an a$$ but I just looked up some random sleeves on Summit, and they seem to average .094 wall thickness. if that is the case, what are you gaining by sleeving it?
Inertia
Well-Known Member
I'm pretty sure there is a "thick" and "thin" sleeve.
Been there .
Been there .
Not only are there thick and thin sleeves, but a sleeve is backed up by the bored out cylinder.
33IMP
Well-Known Member
A properly installed sleeve would probably be the best hole in the block. And I wouldn't worry a minute about not sleeving all of them, one will be fine.
Phreakish
Well-Known Member
Cast iron is not as strong as steel, nor as dense. There's a material property called modulus of elasticity which is lower for cast iron too. It varies with the grade of iron, but steel tends to be stiffer, harder, and stronger and so it can be a thinner wall without risk of failure.
Many sleeves are also made from cast iron to avoid a dissimilar material situation. Cast sleeves are likely made from a higher grade with properties closer to that of steel, or at least in excess of what a typical block is made from. They're also typically going to be very consistent since there's no cores for water passages as such. That consistency means a lot when it comes to strength.
Also, a thin spot in a block could be an indicator of corrosion or other inclusion. There's no guarantee the 'thinness' is the result of just a thinner or shifted wall. It could be a bubble, entrapped sand, or a shallow crack which has preferentially corroded to a deeper 'pit' than other areas. Short of x-ray, it's hard to determine the cause of the thin wall - sleeving it avoids having to lose sleep over it or taking the 'wait and see' approch, which may result in a failure sometime down the road.
I've had blocks sleeved before, and after seeing the process and the results, it's nothing to try and avoid IMO. Done properly, the block will be better/stronger than before sleeving.
I think its cast issue. What i saw from plug holes and from waterpump holes water jacket looks very good for that old block, clean and not rusty. Wall thickness from opposite side of bore is nearly 0.300. And thats thickness about 40% of bore. Other bores are much more constant around.
Sleeves aren't an issue. Back in the 70-80's, a friend worked at a boring company...here in Motown. They did all the Petty blocks...and they all got 8 sleeves. They were all straight, and uniform/proper thickness.
Jeremiah (jd)
Well-Known Member
I have sonic checked many 400 blocks and even blocks with bores mostly at >.180 thickness have scarey/thin spots.
That said most of the cracked cylinders I have seen, including my own, began to crack parallel to the deck at the top of the cylinder on the thrust side. Eventually the crack takes a path down the cylinder making it an "L" shape.
Stab a Dorton sleeve in it and it should be fine
That said most of the cracked cylinders I have seen, including my own, began to crack parallel to the deck at the top of the cylinder on the thrust side. Eventually the crack takes a path down the cylinder making it an "L" shape.
Stab a Dorton sleeve in it and it should be fine
I would absolutely sleeve it and like already mentioned it will be the best hole you have in the block.
Tom
Tom
-
