What is core shift?

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dusted72

Thanks Hemiroid!!!!
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Isi it just what it says? The core of the block has shifted? How is that possible? And exactly what constitutes the core? Thanks I just don't know.
 
It has always been my perception from the context of the term being used, that it was a fault in the casting process. In other words, the core was not dead on center, when the block was cast.
 
The core of the mold used to cast the block is what shifts. This results in the core of the block being shifted.

This is why molds are regularly replaced and updated.
 
Yup, it just means that in the casting/machining phase, the cylinder walls are closer to the cooling passages on one side than another. Ideally, you like them the same distance all the way around so you can overbore the block without overheating problems from hot spots where the wall is too thin.
 
Yes, core shift occurs during the sand casting process. It results in different wall thicknesses from side to side. The foundry had to rebuild the casting molds numerous times due to wear and tear on them during the process. A new core "series" number is then cast on the side of the blocks.
 
It is acutally present in most cast products. Heads, intakes, blocks, etc. The sand in a casting mold is the open areas in the finished part. So as an example, the cylinder bores have a casting core, the cooling jackets have a casting core... A block casting mold can contain a bunch of cores, and these sometimes shift while the process is being done. So you end up with the finished castings having rough parting lines, or thin spots as noted.
 
Or in other words, a bunch of cores (cylinders, cooling, etc) are bunched together into 1 central core then the molten iron is poured.

Somewhere in the process, they get slightly out of alignment..

Sorta like trying to align your fender to the door and the door to the 1/4 panel.
 
it usually occurs gradually over time, they get slightly further out of alignment as each cast is made
 
Thanks guy I am a little smarter now. See there are still things to be taught and learned out there. I am sure there are others that didn't now either and they just didn't want to ask. :)
 
Hey dusted

A little off the subject, but every time I see your new avatar (I like it)
I think of my nephew David (needahotrod) here on the Forum. He spent
some time in the sand box during Desert Storm. He was a M88 driver and
Bradley mechanic.

I always kid him about the second picture...I hit him with Rambo:D

He's still in the Active Reserves...just turned in his packet for Sgt. Major

When's your date up or are you career?
 

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Hey Tony,
I actually just reenlisted in December for 6 years. That will put me at 2016 and 13 years active duty. Don't know why I would ever get out before 20 years but then again they are offering EOD Techs 90k and up in most civilian job markets.
 
I don't know, seen the last month job's report ? NO NEW JOB'S were created--in fact likely next month they be telling us the USA lost the number of jobs.

Job's are hard to find, let alone 90's ones. Not saying you couldn't find a job--no way with your background you be hired for sure--but for how much $$ its hard to say.

Bet you could handle Texas heatwave, lol. I believe Iraq is 10--20 degrees hotter than any place in Texas during the summer.
 
They are always looking for Secret Service guys. :D You think the Pres is gonna go without security.
 
I went to Washington DC for 5 days last spring-early summer. Its SUPER NICE down there. If you could get in working with the US Park Police I say go for it. It might be boring thou, many officers I seen were just standing around keeping an lookout, they don't speak to the tourist unless the tourist is doing something they should not. Like I locked up my bicycle near the Capital building and nobody says anything to me but as soon as I walked away from the bike I got yelled at that I can not leave my bike unattended--guess it could have been a bomb, sure you know how that game goes.
 
Hey Tony,
I actually just reenlisted in December for 6 years. That will put me at 2016 and 13 years active duty. Don't know why I would ever get out before 20 years but then again they are offering EOD Techs 90k and up in most civilian job markets.


Please stay safe
 
One thing to keep in mind when choosing a block regarding core shift. The closer to the end of a run with a series of engines, it is more likely to have core shift.....at least this is what I have always read and heard. True or not, I don't know. In other words, the molds are newer towards the beginning run of a given engine. Say the 72 and 73 340s for example would have more core shift than the early ones....at least according to that theory. Whether there's truth to it or not who knows? Just something I've always heard. I guess it all depends on how many blocks were cast off the same mold and how often the molds were replaced. I'd like to pick someone's brain that actually worked in the foundrys and find out. Best thing to do if you're in doubt is sonic test it.
 
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