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Re: Has anyone experienced Core Shift????
[Re: Imrare]
#1631477
06/10/14 01:17 PM
06/10/14 01:17 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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I Live Here
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I haven't. But since UT testers became more widely used, there have been many many virgin blocks found to have one or more cylinders with 0.090 or less in a running engine. That is at the ragged edge of what's considered minimum wall thickness for a non-thrust side. So take another 0.015" off the cylinder wall and you will have problems. One of the members talked a few years ago about finding a 400 cold weather block only to find a really thin cylinder wall. As far as I know, the block is still sitting in the shop. Another engine builder UT'd a lot of 400 blocks and found that many of them had one or possibly two cylinders that needed sleeves, the rest were OK. 60 over 440s have a high probability of having heating problems. Some run fine, some don't. The problem isn't limited to any stretch of years, either. So based on the testimony with which I am familiar, there is enough probability of a used block having a thin cylinder or two or more, to make it imperative to UT the block before you sink any money in it for machining. May not be the answer you were looking for, but that's my  . R.
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Re: Has anyone experienced Core Shift????
[Re: Imrare]
#1631479
06/10/14 01:44 PM
06/10/14 01:44 PM
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Joined: Jan 2003
Posts: 20,212
Park Forest, IL
slantzilla
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Park Forest, IL
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What exactly is it doing and what has been done so far to try and correct it?
Unless you are running some really high compression a .030" bore shouldn't cause that kind of a problem, especially if it's a 383.
"Everybody funny, now you funny too."
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Re: Has anyone experienced Core Shift????
[Re: slantzilla]
#1631480
06/10/14 01:58 PM
06/10/14 01:58 PM
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Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
JohnRR
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Quote:
What exactly is it doing and what has been done so far to try and correct it?
Click his name and look at the many many threads on the issue  make sure you have a long time to take reading it.
If I remember right the issue is he can't let the car sit and idle for hours on end with the outside temp being above 100 degrees and no movement of air thru the radiator other than what the fan pulls .
Balancing and blueprinting was not the fix ... but you knew that. ... there are many many core shifted engine out there , they all have core shift to one degree or another.
Did you have the block sonic checked while you were pouring more money in it ?
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Re: Has anyone experienced Core Shift????
[Re: JohnRR]
#1631483
06/10/14 05:28 PM
06/10/14 05:28 PM
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Joined: Jul 2007
Posts: 291
St. Louis
Imrare
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St. Louis
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No, I did not have it sonic tested...no one mentioned core shift until after the latest engine rebuild, which did absolutely nothing!
As a matter of reference, the engine builder(AMT Performance in St. Louis)ran the engine on an engine stand to break in the cam, etc. for about 15 minutes or so at which time we had to shut it down because it had completely heated up the 55 gal drum of water we were using for coolant. Temp in the shop was about 45 degrees. We were able to verify that the water pump was pumping like crazy! Subsequently, they (AMT Performance) tell me, a week or so later they ran another freshly built 383 which was developing quite a bit more power than my stock rebuild and it never did get the barrel hot. I wasn't there to see this, but that is what he tells me and they (AMT) have no answers as to where all of the heat is coming from?
The theory that has been given to me is that the engine may have had a core shift from the factory that wasn't quite bad enough to not cool the engine when it was new but when the block was bored 30 over, enough material was removed to throw it over the edge to where it will not cool when idling. Seems far fetched to me that an engine 45 years old would still be with the same car if it had a core shift issue, however, I am now totally out of possibilities I can try to solve the problem. In the end, core shift or not, I believe my only fix now is to purchase a new engine. In fact, I would not feel comfortable using ANY of the parts from the current engine on any new short or long block that I purchased.
Does a core shift on this engine seem feasible? Basically, that means my new rebuilt engine is JUNK!
I can keep showing the car as I have in the past and drive on days that are not so hot, but man this really has me frustrated!
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Re: Has anyone experienced Core Shift????
[Re: Imrare]
#1631485
06/10/14 09:50 PM
06/10/14 09:50 PM
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Joined: Jan 2003
Posts: 75,094
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JohnRR
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Posts: 75,094
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Quote:
No, I did not have it sonic tested...no one mentioned core shift until after the latest engine rebuild, which did absolutely nothing!
As a matter of reference, the engine builder(AMT Performance in St. Louis)ran the engine on an engine stand to break in the cam, etc. for about 15 minutes or so at which time we had to shut it down because it had completely heated up the 55 gal drum of water we were using for coolant. Temp in the shop was about 45 degrees. We were able to verify that the water pump was pumping like crazy! Subsequently, they (AMT Performance) tell me, a week or so later they ran another freshly built 383 which was developing quite a bit more power than my stock rebuild and it never did get the barrel hot. I wasn't there to see this, but that is what he tells me and they (AMT) have no answers as to where all of the heat is coming from?
Did they try a different carb to eliminate it being way to lean ? Did they bump the timing up to make sure it wasn't getting hot because of that ? it should have been above 35 degrees advanced when they were breaking in the cam ... and a fresh engine is going to run hotter ... but you know that ...
Quote:
The theory that has been given to me is that the engine may have had a core shift from the factory that wasn't quite bad enough to not cool the engine when it was new but when the block was bored 30 over, enough material was removed to throw it over the edge to where it will not cool when idling.
Your idling criteria is crazy , there is zero reason to leave the car sitting idling for as long as you have claimed you have ...
Quote:
Seems far fetched to me that an engine 45 years old would still be with the same car if it had a core shift issue, however, I am now totally out of possibilities I can try to solve the problem. In the end, core shift or not, I believe my only fix now is to purchase a new engine. In fact, I would not feel comfortable using ANY of the parts from the current engine on any new short or long block that I purchased.
Sorry that is just ludicrous
Quote:
Does a core shift on this engine seem feasible? Basically, that means my new rebuilt engine is JUNK!
Anything is possible , it would have to have some seriously shifted cylinders , like all of them .... but NO it's not junk.
Here is a way to fix the core shift, if it is core shifted, have all 8 cylinders sleeved to bring the engine back to original bore size .. it is your original engine so it's worth it ... if it has core shift sleeving it will eliminate that issue because the badly shifted cylinders , if there are any , will be replaced by fresh round sleeves that will eliminate that issue if it's sleeved properly.
If this engine is core shifted as badly as it would have to be to overheat like is being claimed then you would be able to see it in places when looking at the bare block.
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Re: Has anyone experienced Core Shift????
[Re: JohnRR]
#1631486
06/11/14 11:36 AM
06/11/14 11:36 AM
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Joined: Jan 2003
Posts: 20,212
Park Forest, IL
slantzilla
Too Many Posts
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Posts: 20,212
Park Forest, IL
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Pretty much any 383 has enough wall to go +.060" easy and usually +.100". I'd check elsewhere.
"Everybody funny, now you funny too."
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Re: Has anyone experienced Core Shift????
[Re: Imrare]
#1631487
06/11/14 01:27 PM
06/11/14 01:27 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
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Cincinnati, Ohio
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Quote:
I would have thought that engines produced in the late 60's that were subject to a "core shift" would have been disposed of long ago by attrition or warrantee claims. I'm finding that some of these may have survived.
Has anyone experienced Core Shift in an engine block (383, 440, etc.) that did not become a problem until years later when the block received its first 30 overbore? By problem I mean overheating or cracked cylinder wall.
Has anyone really found "core shift" to be responsible for over heating?
I didn't don't have time to read all your old posts about this problem, have you ever changed the tune up to see if that would help?
Is the carb the same as it was in 1969 inside?
Have you tried to run the car on 100% leaded 110 race gas?
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Re: Has anyone experienced Core Shift????
[Re: slantzilla]
#1631488
06/11/14 02:32 PM
06/11/14 02:32 PM
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Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
JohnRR
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Quote:
Pretty much any 383 has enough wall to go +.060" easy and usually +.100". I'd check elsewhere.
That all depends , one of the mods ... has shrek for his avatar ... did a 383 based stroker on a .060 block , one of the cylinders split because it was too thin.
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Re: Has anyone experienced Core Shift????
[Re: JohnRR]
#1631489
06/11/14 03:51 PM
06/11/14 03:51 PM
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Joined: Feb 2003
Posts: 10,234
Someplace you aren't
SomeCarGuy
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To answer the original thread title question- yes, core shift is not uncommon and known to be an issue in all years and blocks. If you have exhausted all of the what sound to be dozens of things to try for overheating, tear the damn thing back down and have it checked. There is no point in keeping on with questions. Take the suggestions or don't. We don't care.
I want my fair share
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Re: Has anyone experienced Core Shift????
[Re: JohnRR]
#1631490
06/11/14 04:32 PM
06/11/14 04:32 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
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Cincinnati, Ohio
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Quote:
Quote:
Pretty much any 383 has enough wall to go +.060" easy and usually +.100". I'd check elsewhere.
That all depends , one of the mods ... has shrek for his avatar ... did a 383 based stroker on a .060 block , one of the cylinders split because it was too thin.
I have a standard bore 340 that cracked a cylinder from sitting with anti freeze in it for 20 years after I ran it for 3 years.
It's the one I took apart in my driveway, you have seen the pictures.
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Re: Has anyone experienced Core Shift????
[Re: cedarmachine]
#1631495
06/12/14 11:42 AM
06/12/14 11:42 AM
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Joined: Jul 2007
Posts: 291
St. Louis
Imrare
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enthusiast
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OP
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St. Louis
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John, the idling criteria is not ludicrous, if it is a hot day, setting at a stop light for 2 cycles can be enough to take the temp over 200 degrees and unless you get moving, it will cook the engine. Or, ever get caught in bumper to bumper traffic, I have and have had to pull off the road and shut down the engine. Anyway a review of my posts will indicate that over the years, timing has been adjusted 15 degrees advance, 10 degrees retarded, set at TDC, all over the place, no change, same MO. Right now, after the rebuild, it is set at 15 BTDC initial. I have not changed the Carb. If I did, there is no guarantee that that a new carb purchased would meet factory specs as well? We have however increased the jet size, changed the metering rods, etc to richen it up (the engine builder said it was running very lean), but honestly, I don't think we know where the carb is as far as factory specs go. That being said, even if it was a little on the lean side at idle, I don't see that causing the tremendous amount heat that exists when it is only making, what, 40 hp at idle? What puzzles me is this engine has run fine for over 40 years, it is a mechanical device that now has a problem, we just haven't found what that is yet. As much as I hate it, from what I'm hearing, I need to tear the engine down again and have it Sonic Tested so that I have a base line to start from. But again, with the years of service that this engine has seen, I am reluctant to think that if it did have a slight core shift from the factory that it didn't become a problem until the 1st bore and rebuild but I guess it is possible.
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