Has anyone experienced Core Shift????

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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?

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 ...

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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.

Posted By: WO23Coronet

Re: Has anyone experienced Core Shift???? - 06/11/14 10:21 PM

No expert here but having .015" less material in the bore (per side) doesn't seem to make sense to me for causing an overheating issue. I'm sure there's plenty of engineering types that could chime in but surface area (which hasn't changed) would seem to be more important that a small change in thickness. I think your problem lies elsewhere, if the walls were that thin you would've likely had problems with overheating before.

Also, is there any merit to the thin wall causing overheating arguement? I'm sure it does have some small effect but it seems overblown to me

Posted By: GODSCOUNTRY340

Re: Has anyone experienced Core Shift???? - 06/12/14 04:32 AM

Set the initial timing to 19 degrees BTDC and see if it still overheats.

Posted By: 72chrgrally

Re: Has anyone experienced Core Shift???? - 06/12/14 06:06 AM

What's the piston to wall clearance?

Posted By: cedarmachine

Re: Has anyone experienced Core Shift???? - 06/12/14 11:34 AM

We sonic test everything. I literally buy ultrasonic gel by the quart.

With sonic testing, we can determine if the block is worth building. Also, it allows us to move the cylinders slightly, when boring them. This keeps the thrust side as thick as possible in cases where they may have shifting that would put it in jeopardy of flexing more if made thinner by boring.

Without sonic testing, my BHJ Bore-Tru tooling would be useless. You need this critical information before trying to relocate a bore into correct index. On some blocks, you just can't do it because of core shift.

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/12/14 03:42 PM

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.

Posted By: slantzilla

Re: Has anyone experienced Core Shift???? - 06/12/14 03:45 PM

How hot does it really get? 200* is not that bad.

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/12/14 04:08 PM

I have had it get in excess of 215, so hot that is sounded like a diesel right before I shut it off, so hot that as the engine is cooling, it "creeks" like a hot ember after it is shut off, so hot it melted the plastic steering column bearing at the bottom of the steering column, so hot that it shrunk up the steering column white fire wall gasket to the point it was unusable and had to be replaced. Believe me when I say...the engine overheats, that is a fact, it is verified! My question is related to Core Shift and is that why it is overheating?

Posted By: MOPARMIKE69

Re: Has anyone experienced Core Shift???? - 06/12/14 04:29 PM

Quote:

I have had it get in excess of 215, so hot that is sounded like a diesel right before I shut it off, so hot that as the engine is cooling, it "creeks" like a hot ember after it is shut off, so hot it melted the plastic steering column bearing at the bottom of the steering column, so hot that it shrunk up the steering column white fire wall gasket to the point it was unusable and had to be replaced. Believe me when I say...the engine overheats, that is a fact, it is verified! My question is related to Core Shift and is that why it is overheating?

First let me say I can relate to your frustration. You have done so much to find the answer to this problem with nothing to show for it.

The fastest and least expensive and most definative thing you can do right now is... get another block with the same bore. Rebuild it with all that you have already and dyno it. Block might cost $300. Engine reassembly some gaskets and time. I could do it in one day. $500 for the dyno. Done, all doubts removed as to whether it is the block or not.If it works put it in the car and finally enjoy your cool ride. You will still have your numbers matching block for the car, when and if you decide to sell it.

If it still over heats then obviously you will never doubt your numbers matching block and you will then at least have a solid base for tracing down your problem. You have been fighting this for what 2 years. You can put to rest all your doubts about this block in one week and less than a grand.

Best of luck in your efforts

Posted By: Andrewh

Re: Has anyone experienced Core Shift???? - 06/12/14 04:39 PM

as I recall you are trying to run a 22 inch rad with 3 row core, mechanical fan and no shroud.

have you pulled the tstat and seen if it still overheats at idle?

I still feel you are lacking in the cooling department.
there is no reason a proper setup cannot hold the t stat temp at idle.
where you show excessive build up, at idle, but not during movement just re-enforces the fact that you don't have sufficent air flow.

I really cannot believe your engine is producing more heat at idle then cruising at 55 mph.

Posted By: BDW

Re: Has anyone experienced Core Shift???? - 06/12/14 05:03 PM

I think I would be trying a 26" radiator with a shroud before tearing down and rebuilding the engine.

Water wetter is only $12 and supposed to help.

Posted By: JohnRR

Re: Has anyone experienced Core Shift???? - 06/12/14 05:31 PM

Quote:

I have had it get in excess of 215, so hot that is sounded like a diesel right before I shut it off, so hot that as the engine is cooling, it "creeks" like a hot ember after it is shut off, so hot it melted the plastic steering column bearing at the bottom of the steering column, so hot that it shrunk up the steering column white fire wall gasket to the point it was unusable and had to be replaced. Believe me when I say...the engine overheats, that is a fact, it is verified! My question is related to Core Shift and is that why it is overheating?

The steering column bearing did not melt from engine coolant temp, it melted from too high exh temp , lean idle will cause the manifolds to grow bright red as will not enough timing.

The engine shouldn't overheat from sitting at 2 light cycles unless the light cycle is over 10 mins ?

What is your history with this engine BEFORE the rebuild, was it overheating then?

The only other 383 I know of that had and overheating issue was with one that had pin hole leaks in the side of the block that wouldn't allow the cooling system to build pressure. I worked on a 440 that had the same problem , once the leak was fixed the issue went away.

Posted By: JohnRR

Re: Has anyone experienced Core Shift???? - 06/12/14 05:36 PM

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as I recall you are trying to run a 22 inch rad with 3 row core, mechanical fan and no shroud.

My 69 Dart has a 22" 3 row radiator , mechanical fan but wit ha shroud. I have run it on the highway at 65mph with 3.91 gears and F70-14 tires, RPM was up over 3k, in 95 degree heat and it was fine.

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/12/14 06:26 PM

To answer another post, you can't put a 26 inch radiator in a 22 inch core support for obvious reasons. I have recently reinstalled the OE shroud back on the radiator even though the car is not coded that way. There has been no change in MO. I've owned more than one Plymouth/Dodge in the past with 22 inch radiators (no shroud) and they ran plenty cool, never a problem. So I know the radiator is adequate. Just as a note, I've also tried two other radiators, one a Max Cool Radiator from Glen Ray Radiators in WI, no change in the overheating problem. And yes, it does cool down when I'm driving at 55 but I'm not sure it would on a really hot day after the temp reached elevated levels.

MoparMike, thank you for your understanding, I am very frustrated and have been working this problem, on and off, for the last 5 years. I've only become really serious about it in the last 2 or 3 years because I always thought there must be some simple explanation to the problem and I've "done the show car" thing and now want to actually drive the car...plaques and trophies only go so far.

I've made arrangements to try a new carb on the car in the next few weeks, just because everyone says try it, I don't expect it to make a difference, but I don't want to leave any stone unturned. Then, if that doesn't work, after the Mopar Nationals, I am going to tear down the engine and have it sonic tested and see what those results are. I don't know what else to do at this point.

Posted By: Andrewh

Re: Has anyone experienced Core Shift???? - 06/12/14 07:31 PM

you can put a 26 in in a 22 core support. my self and plenty of other members have done so.

a change in the raditor isn't your only issue.

air flow is the main problem.

at around 45 mph no fan will pull as much air as is being pushed through by speed.

if at 50 mph your car maintains cooling, then you do not have a cooling system issue.
you have an airflow issue.

while a shroud might help, on boarder line issues, yours seems to be much worse than that.

additional cooling capacity using a 26 inch rad would bandaid the air flow problem.

just cause you don't want to hear it, doesn't make it untrue.

the wrong answer is always, we have always done it like that, and it worked before.

if you can get a giant shop fan and blow air over the rad at idle, you can prove it is an air flow issue. not an engine or coolant capacity issue.

Posted By: autoxcuda

Re: Has anyone experienced Core Shift???? - 06/12/14 07:56 PM

Quote:

you can put a 26 in in a 22 core support. my self and plenty of other members have done so.

a change in the raditor isn't your only issue.

air flow is the main problem.

at around 45 mph no fan will pull as much air as is being pushed through by speed.

if at 50 mph your car maintains cooling, then you do not have a cooling system issue.
you have an airflow issue.

while a shroud might help, on boarder line issues, yours seems to be much worse than that.

additional cooling capacity using a 26 inch rad would bandaid the air flow problem.

just cause you don't want to hear it, doesn't make it untrue.

the wrong answer is always, we have always done it like that, and it worked before.

if you can get a giant shop fan and blow air over the rad at idle, you can prove it is an air flow issue. not an engine or coolant capacity issue.

Very good points.

But I do understand Imrare's fustration that IF his car was rebuilt 100% stock, the stock system should cool it.

Question is, is it 110% stock? The only thing I can think of as not controlable as stock would be the gas. Is that enough to cause things to go over the tipping point?

On the far out wacky side to pour gas on this fire... could there be something hidding inside a coolant passage inside the block or heads blocking flow that would be overcome at speed with airflow but be a problem idling? Just hot tanking will not get some heavy scale out. I've seen freeze plugs and bits of freeze plugs in motors from when someone knocked one in when replacing. Could that get lodged in a mysterious place?

Posted By: cudaman1969

Re: Has anyone experienced Core Shift???? - 06/12/14 08:26 PM

My thoughts keep going back to the head gasket. Have you pressure tested each cylinder? Does it hold pressure in the radiator for hours? Maybe some of the coolant holes in gasket are blocked. Since you ran it with the 55 gallon tank that eliminates the radiator. I would also run a EGT gauge to check the exhaust temp. One other thought was pistons or rings to tight, to much friction, low drag ring pack runs cool. Pull the heads and look at the gasket and cylinder walls for scoring.

Posted By: MOPARMIKE69

Re: Has anyone experienced Core Shift???? - 06/12/14 08:35 PM

Again in a week and for less than a grand you can know for sure if it is the block. Even if you sonic test the block you still won't know if that is why it is over heating. You hopefully will find out if there is blockage in the water jackets or if you need to re-sleeve.

The car is stock and he has a ton invested to make it that way. It is a beautiful car so rigging in a 26 inch isn't an option.

If you go back and look at the threads every conceivable option to help him find out the answer to this overheating problem has been suggested. Whether or not he has explored them all only he knows. That is why he is at the point of questioning "core shift".

Posted By: Andrewh

Re: Has anyone experienced Core Shift???? - 06/12/14 08:40 PM

again, I didn't say stuff a 26 in. I pointed out it is possible.
however I still feel it is an air flow issue that needs to be addressed.

he should check that first.

not even going to cost him anything to try.

none of the issues he sees should get better the faster he goes.

a blockage would just be worse moving faster.
think about the pinched hoses we have heard about at speed.

just arguing a 22 inch with or without a shroud cooled stock mopars doesn't mean it works everywhere.
doesn't mean the fan is correct, with the correct pitch. or the correct pulley for the right speed.

each item can be tested, as everyone has sugguested.
mine is a simple test that costs nothing to try.

if it keeps up then, you know where to start looking.

if it doesn't, then you know to tear into the block and replace it.

Posted By: autoxcuda

Re: Has anyone experienced Core Shift???? - 06/12/14 08:51 PM

Quote:

...

a blockage would just be worse moving faster.
think about the pinched hoses we have heard about at speed.

...

That makes sense.

Posted By: JohnRR

Re: Has anyone experienced Core Shift???? - 06/12/14 09:06 PM

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That is why he is at the point of questioning "core shift".

Anything is possible, but that is why I asked his history with the engine before the rebuild.

A friend had a 440 that was .060 over, it was a race engine but to what degree? He took it out of the car he had it in with headers and single plane high rise intake and put it in his 69 Satellite wagon , with stock exhaust manifolds and a dual plane 4bbl, it never ran cool after the transplant , before I have no idea as I didn't know him then. I'm not sure how much too big a cam and stock manifolds played against each other ??? and/or the maxish overbore and higher compression ratio? Or if it was being helped/caused by the auto transmission???

Also in all this playing around wit hthe timing , retarding it 10 degrees after TDC definitely wasn't going to help, was the mechanical advance in the distributor changed to work with the non stock setting or left stock?

Posted By: mikemee1331

Re: Has anyone experienced Core Shift???? - 06/12/14 09:47 PM

there could also be an oiling issue. lubing is NOT it's only function....

Posted By: cudaman1969

Re: Has anyone experienced Core Shift???? - 06/13/14 12:10 AM

I just remembered one thing from the past(1973) my 426 max wedge had four sleeves(.060 over) when i bought it and ran 160 all day. One cracked got oil in water, went to replace sleeve and low and behold no cylinder wall behind sleeve on two holes so block went on the pile, but the point is it didnt run hot with those paper thin sleeves. Just think of the things that where changed ,replaced or altered and there is your problem. Core shift no.

Posted By: Challenger 1

Re: Has anyone experienced Core Shift???? - 06/13/14 04:33 AM

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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.

Your engine builder tells you it's lean, you don't have any idea where or how the tuning is withthe carb and your running ethanol gas?

Yes lean will cause it to run hot, sure he!! Will.

Is is not core shift IMO

Learn to tune your carb is my suggestion.

Post your jets needles here we c an tell where your at with carb.

Why don't you believe the engine builder? He knows your motor best.

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/23/14 04:06 PM

In speaking with many individuals here and others, it seems pretty unlikely that this engine has been overheating for 45 years. If it had, it would have had a warranty block by now. So probably no core shift.

It was determined when the engine was rebuilt (last winter) that both heads had been �monkeyed with�. They had both been ported on the intake side. Also, and maybe more important, two repairable cracks were found in what is now the Drivers side head. Since the heads had the expensive �porting� the rebuilder convinced me to let him repair the cracks and not replace the heads.

Since now finding that the rebuild did not uncover any issues related to overheating, and since the same problem persists exactly as before the engine was rebuilt, my assumption is that whatever is causing the overheating is still part of the engine. Therefore, with the block ruled out, I have begun to focus on the heads.

Since each side of the engine is a closed loop cooling system until meeting at the water pump and then going on into the radiator, I performed an analysis whereby starting with the cold I took temperature readings of each head at two minute intervals with the engine warming up from idle. I did this analysis on Saturday and Sunday. The outside temp on Saturday and Sunday morning was 80 and 70 degrees respectively. The humidity was 90% and 87%.

Unfortunately, I could not get my excel worksheet to copy into this post but the bottom line is in all phases of the engine "warm up", ( I took 18 readings) the driver's head ran consistently hotter than the passenger side by up to 30 - 40 degrees. Ex. when the Pass head was 150, the driver's head was 190, when pass head was 180, drivers head was 215, etc. Also I then took the car out and drove it, even with the temp gage showing normal, I got out and took the head temp, the pass side was 165, the drivers side was 201.

I believe the increased cool air flow over the radiator was able to handle the heat transfer from the �hot head� and cool the other portions of the engine to a point where it appeared to be normal operating temperature at the sending unit. Once I would stop for a minute or so at a stop light or because of traffic, you could visibly see the temperature gage rise until I started moving again, then it would move down to normal.

So does my analysis prove anything? I think it does. Has anyone ever experienced something like this, with one side of the engine running considerably hotter than the other? Also, is there agreement that this analysis points to a problem in the Driver�s side head?

Posted By: JoesMopar

Re: Has anyone experienced Core Shift???? - 06/23/14 04:22 PM

I have a 440 in my Charger and it will heat up when I'm sitting at an idle like that on a warm day. It won't melt things like you have though. I'm convinced that in my case it's related directly to air flow. I don't have a shroud and I'm running a cheap flex fan.

I still think you have a combination of problems between air flow, circulation, timing and fuel mixture. Did you ever try the "piece of paper" trick on the front of the radiator like some members mentioned?

I wouldn't think it would be too uncommon to have head temp differences between each side, not sure about a 40 deg difference though.

I'll just ask since I didn't see it mentioned anywhere and honestly I haven't read through the entire thread...have you checked your plugs to see how they look?

Posted By: Andrewh

Re: Has anyone experienced Core Shift???? - 06/23/14 04:31 PM

since some cylinders run leaner than others, did you check at all of them?
was it measured in multiple spots along the head?

was it a dark area? (though that might just affect actual vs read) some IR thermometers require reading on a dark surface not polished aluminum.

not saying this isn't your problem, but not saying it is.
scientific method and all. single data points don't tell you anything.

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/23/14 04:36 PM

Tried the paper test, it passed. I'm getting adequate air flow.

Posted By: JoesMopar

Re: Has anyone experienced Core Shift???? - 06/23/14 04:38 PM

Did you look at the plugs? Are you sure you have good coolant circulation?

If you sit at idle and it starts heating up, will it start dropping back down if you just raise your RPM's or only when you get moving?

Posted By: cudaman1969

Re: Has anyone experienced Core Shift???? - 06/23/14 05:01 PM

I would say the hot head is the cracked-repaired one. A restriction or more cracks. Ever lost water from radiator or build alot of pressure?

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/23/14 05:55 PM

Never have lost coolant from the cracks...yet.

Posted By: JohnRR

Re: Has anyone experienced Core Shift???? - 06/23/14 09:47 PM

Easy enough , and not super expensive to figure out , get another pair of heads , or at least replace one... BUT I'm pee in the punch, thin cylinders on that bank COULd be putting more heat in the coolant on that side and causing it to run hotter , or the coolant is somehow being restricted.

One way to figure out if it is the head that is causing it , swapp the heads side to side and see if the heat moves. I'll supply the head gaskets if your're up for the challenge. If you lived closer to NH I'd do the work.

This is getting interesting.

Posted By: Imrare

Re: Has anyone experienced Core Shift???? - 06/24/14 12:47 AM

Quote:

Easy enough , and not super expensive to figure out , get another pair of heads , or at least replace one... BUT I'm pee in the punch, thin cylinders on that bank COULd be putting more heat in the coolant on that side and causing it to run hotter , or the coolant is somehow being restricted.

One way to figure out if it is the head that is causing it , swapp the heads side to side and see if the heat moves. I'll supply the head gaskets if your're up for the challenge. If you lived closer to NH I'd do the work.

This is getting interesting.

JohnRR, that is an excellent idea...that is exactly what I will do. Obviously if the heat moves to the Passenger side, we've found it, if the Driver's side remains hot, more than likely a "block problem". Since the engine compartment is "all detailed" up, I am going to wait until after the Mopar Nationals (August) to do this. I should be able to remove the heads in one weekend and re-assemble it the next (okay I'm slow). The shop that rebuilt the engine wants me to try a new Carb before I do anything else, he doesn't think it is the head. I told him I would try a new carb but that I thought it was unlikely that an improper fuel mixture would only affect one side of the engine. Do you agree?

Has anyone experienced Core Shift????