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28 Chrysler 25" Engine tear down and rebuild


maok

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The springy thing is a piston skirt expander which was used to make the piston run quietly in a worn cylinder.  

Still, in all, more positive than negative.

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10 minutes ago, dpollo said:

The springy thing is a piston skirt expander which was used to make the piston run quietly in a worn cylinder.  

Still, in all, more positive than negative.

That explains why the skirt is slightly larger than the crown of the piston. Thanks for the education.

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The measurement at the crown is smaller than the skirt because expansion is greater there.   Also the skirt area is cam ground so measurements will vary around the skirt circumference.

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  • 2 months later...

Hey guys, I'm scratching my head trying to figure out what is hindering the removal of the cam. I am assuming it should be the same as later Mopar flatheads.

It is a bare block with only the cam and lifters still remaining. The block is upside down and all the lifters are lowered, so are not interfering with cam lobes. When I try to pull the cam forward it seems to be making contact at the rear of the block but I can see anything obvious that its making contact with. My shop manual has no instructions for removal and I cant seem to see anything in the diagram that holds it in place at the rear of the block.

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8 minutes ago, maok said:

Hey guys, I'm scratching my head trying to figure out what is hindering the removal of the cam. I am assuming it should be the same as later Mopar flatheads.

It is a bare block with only the cam and lifters still remaining. The block is upside down and all the lifters are lowered, so are not interfering with cam lobes. When I try to pull the cam forward it seems to be making contact at the rear of the block but I can see anything obvious that its making contact with. My shop manual has no instructions for removal and I cant seem to see anything in the diagram that holds it in place at the rear of the block.

You must spin it on the way out. Pull until it stops and spin it again until it comes all the way out.

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Nope, no luck with spinning it. Even spinning it very slow while pulling it forward, I cant feel it un-locating or dislodging in anyway.

It will pull out about 5mm (1/4") then it seems to stop with the cam hitting from the front and back.

IMG_4274.JPG.f7db737c4caed678a20f02c15ad6fc49.JPGIMG_4275.JPG.b9fb8eed7d41c8794dec8eef00f12a90.JPG

IMG_4276.JPG.100551e1c8ffd268ecd3fc1e59032c91.JPG

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Here is the cut-away view.

599b7d05f3313_UserManualpage24.jpg.faa7132bf3f881736d38594e9ca95d9b.jpg

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No oil pump.

The block is bare, except the cam and followers. Definitely not being fouled by the followers.

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Ok, mystery solved not but the problem.

I don't know why, but it seems like the 2 inner cam (bearings) journals are fouling on the 2 followers forward of them. When I spin the cam when its in the most forward position by 5mm it will spin the follower. How could this be? Surely all the followers when in the lower position (when upside down) should clear the cam (bearings) journals when its being pulled forward out?

IMG_4283.JPG.55d0092be7dcb2cc792f2a5831f8b915.JPG

Edited by maok
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Well, another mystery. Its either a 2 piece follower/lifter or its broken. It does feel like they integrate together.

This one that has dropped is not the offending one, its the one just forward of it. While I was removing lock nut and bolt, it started to come apart from the 'head' of the lifter. It will re-attach by pushing it back up and twisting. It doesn't seem to be a full length of thread though. 

I cannot seem to de-attached any of the others because I cannot get enough grip with my finger and thumb over and around the cam to hold on the head of the lifter to twist apart.

IMG_4286.JPG.e9f6c9a1a6146e92ce3570fdba2b6153.JPG

 

I'm guessing that the lifter that is fouling the cam (bearing) journal is sitting a little high and hence catching the cam (bearing) journal.

Its a catch 22 situation. I cant remove the cam because the lifter is in the way and I cant remove the lifters because the cam is in the way...:eek:

Any suggestions?

Edited by maok
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42 minutes ago, maok said:

Its a catch 22 situation. I cant remove the cam because the lifter is in the way and I cant remove the lifters because the cam is in the way...:eek:

Any suggestions?

No suggestions-way out of my league. But I understand your frustration 

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6 minutes ago, medium_jon said:

No suggestions-way out of my league. But I understand your frustration 

I prefer to think more of it as 'character' building....:D

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3 minutes ago, maok said:

I prefer to think more of it as 'character' building....

The character in me says to walk away from that for a couple of days and work on something else until someone can help you twist them apart-if I'm understanding the issue

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you have a serious issue if the cam bearing is rotation and coming forward to hit the lifter.  It is hard to see your picture but this is the actual cam journal.  My only suggestion is to rotate the cam to bottom of the lobe faces lifter giving you room to work, lift the lifter as high as you can to the lobe of the cam and clean it of baked on oil buildup.  These are tight tolerances and a small varnish ridge can be a monster of a resistance.  The lifter faces must be positioned lower than the cam journal...best part is they stepped smaller as it goes deeper in the block, get the first one by, your tolerance will only increase from there.

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Sorry, I've used the wrong term. The cam journal is making contact with the lifter when the cam is pulled forward. So the lifter in its lowest position (the block is upside down) is not clearing the  journal of the cam.

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I agree the lifter may be in the lowest position...but agree that it HAS to go lower...ascertaining what is needed to do that is your only valid step if you wish to remove the cam...you are removing cam from the front right?   sorry had to ask...logic says if it is at the lowest point, how it could have been assembled in the first place...get a cup of coffee and study this a bit more...

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1 hour ago, Plymouthy Adams said:

 My only suggestion is to rotate the cam to bottom of the lobe faces lifter giving you room to work, lift the lifter as high as you can to the lobe of the cam and clean it of baked on oil buildup.  These are tight tolerances and a small varnish ridge can be a monster of a resistance.

That's my thought too. Something is keeping them from dropping fully into the bores. Most likely a varnish/sludge buildup. Push them back up and clean them up a bit so that they can drop out of the way. You could probably use some carb cleaner spray to break down the buildup layer.

And yes, that one appears to be broken.

Edited by Merle Coggins
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18 hours ago, maok said:

Well, another mystery. Its either a 2 piece follower/lifter or its broken. It does feel like they integrate together.

This one that has dropped is not the offending one, its the one just forward of it. While I was removing lock nut and bolt, it started to come apart from the 'head' of the lifter. It will re-attach by pushing it back up and twisting. It doesn't seem to be a full length of thread though. 

I cannot seem to de-attached any of the others because I cannot get enough grip with my finger and thumb over and around the cam to hold on the head of the lifter to twist apart.

IMG_4286.JPG.e9f6c9a1a6146e92ce3570fdba2b6153.JPG

 

I'm guessing that the lifter that is fouling the cam bearing is sitting a little high and hence catching the cam bearing.

Its a catch 22 situation. I cant remove the cam because the lifter is in the way and I cant remove the lifters because the cam is in the way...:eek:

Any suggestions?

Maybe I'm missing something here?

Can't you remove the tappet rack with all the lifters in it? The two bolts are out of it and on my engines that have this same style rack... remove the two of them to remove the camshaft.

 

413 DT SixTear Down Tappet Guides (3).JPG

413 Six HyD  Lifter cam and Lifter offset (2).JPG

Edited by Dodgeb4ya
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I will have another look today, hopefully its only some sludge or debris that is stopping it from going lower. But it feels a bit too high to be just sludge because the side of the cam journal is making contact with the side of the lifter head, not the face of the lifter.

 

Regarding the removing the rack with all the lifters together, no such luck because the lifters protrudes up into the block ie, the block is cast around the pairs of lifters. So pulling the rack side ways causes the lifter heads to make contact with the side of the block.

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Well....

The engine was made to come apart in a methodical way..... you will find it... please let us know what it is.:)

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25 minutes ago, Dodgeb4ya said:

Well....

The engine was made to come apart in a methodical way..... you will find it... please let us know what it is.:)

That means I need to use logic, in the words of the sage Homer - DOH!

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OK, mystery solved.

The lifter rack is removed by screwing in a bolt into the spacer/towel that holds up the rack on the side of the block and pulling this spacer out.

IMG_20170824_123956.jpg.b485d7e655f4fa03b6b2dfb8907f1ec3.jpgIMG_20170824_124020.jpg

IMG_20170824_125036.jpg.52149a708593da21e84deccff25feb48.jpg

And also, the lifters are 2 piece units. Can you spot the broken one?

Edited by maok
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This is the 2 piece lifter;

IMG_20170824_135824.jpg.1494a70e8dcd9bafc704bd2d8635bfd5.jpgIMG_20170824_140213.jpg.bbd2556576cbe5b6d866b1077e402868.jpg

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