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Pulled motor in woods - warped crankshaft


Bryan
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Was measuring the rod journals on the 48 crank to see if any were tapered, and causing the pistons to be cocked on top.   Measured vertical axis first with rod BDC and then measured sides.  Nothing strange enough to cause the problem.  

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A tapered rod journal will not cause a piston to be cocked. There is simply too much clearance for that. If the journal were tapered it would wear a band on the bearing insert.

A bent rod will.

Pistons do “rock” at the top of the bore (and the bottom as well) but only in the direction of the wrist pin action.

Checking the rods is a job for the machine shop as they have the equipment to do it.

You may think machine shops are sloppy (they are of course) but they know what they can get away with.

You have to trust them and if you don’t like their work, find another. I have my favorites and ones I don’t care for.

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7 minutes ago, Loren said:

A tapered rod journal will not cause a piston to be cocked. There is simply too much clearance for that. If the journal were tapered it would wear a band on the bearing insert.

A bent rod will.

 

Understand that. I checked all the rods using the old "2 rods against each other on a wrist pin" checking for a gap.   I used the same rod for all even cylinders, and odd rod for odd cylinders. If the rod was bent it would cause the piston to be consistently cocked. 

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My results: 251 engine

 

#1 .022 below beck

#2 .022 below

#3 .023 below

#4 .020 below

#5 .023 below

#6 .021 below

 

Upto About .005 difference between front and rear of piston. 
 

My numbers could be more accurate likely. I did what I could with my tool. I cannot speak to any machining as the previous owner rebuilt the engine. I guess he’s not as OCD as us here. He didn’t have records how much was cut away from any areas inside the engine. I measured 040 over on the bore.  
 

I’m gonna “run what ya brung” on this engine and “just send it”. 

Edited by keithb7
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42 minutes ago, keithb7 said:

My results: 251 engine

 

#1 .022 below beck

#2 .022 below

#3 .023 below

#4 .020 below

#5 .023 below

#6 .021 below

 

Upto About .005 difference between front and rear of piston. 
 

My numbers could be more accurate likely. I did what I could with my tool. I cannot speak to any machining as the previous owner rebuilt the engine. I guess he’s not as OCD as us here. He didn’t have records how much was cut away from any areas inside the engine. I measured 040 over on the bore.  
 

I’m gonna “run what ya brung” on this engine and “just send it”. 

Thanks a bunch.  That's what I was expecting with mine, and got worried because it varied so wildly. I did do some measurements earlier today, catching the bottom of the ring ridge and measuring to the bottom of a straightedge sitting on the deck. Previous 53 crank and different pistons would have made the ridge.  About .009" difference between smallest and largest.

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Bryan,

  Advise using depth mics or an indicator over the digital calipers for repeatability reasons. Old school method of measuring is a 4:1 rule for accuracy, depending on user technique of your calipers, you may see .005” variables. Just a suggestion to help aid your results.

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1 hour ago, Sam Buchanan said:

I'm sure the guys who were overhauling these engines in the back of gas stations back in the '40's  were being this meticulous with their measurements.....   😆

 

And back in the 40's they had Doctor's telling people to smoke as it was good for you.

 

Thank god we learned a thing or two since then.

 

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24 minutes ago, 47 dodge 1.5 ton said:

Bryan,

  Advise using depth mics or an indicator over the digital calipers for repeatability reasons. Old school method of measuring is a 4:1 rule for accuracy, depending on user technique of your calipers, you may see .005” variables. Just a suggestion to help aid your results.

Understand that.  Don't have the 53 crankshaft, and the only thing I had to hook on the edge of the ridge was these calipers, to measure to the bottom of the straightedge.

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13 minutes ago, Sam Buchanan said:

Sniper, you just won today's prize for the most irrelevant post.....congratulations!

 

Sorry you missed the humor in my post.

Think you meant irreverent. 

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Just now, Bryan said:

Understand that.  Don't have the 53 crankshaft, and the only thing I had to hook on the edge of the ridge was these calipers, to measure to the bottom of the straightedge.

 

10-4, carry on.  😀

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Trying to be as accurate as I can, but mainly just trying to see why I was getting such a wide variation using the same rod, same piston on the 48 crankshaft.  .012 below deck and .010 above deck is a pretty big deviation.   If my health gets better I'll pull the motor out of another 48 in the woods at my fathers and try the crank out in this 53 block to see what kind of measurements it gives.  Wish I had more data like Keith's.  A few other people's measurements would give me an idea what "normal" is.  I'm doing this one time, and want it right.  I'd be a little less antsy if I hadn't had that block of wood in #3, trying to get the crank nut off.

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I have a virgin motor in the shop and the head is off.  If I get a chance to clean the carbon off the pistons, I’ll see what it measures. The compression was within 5 psi on all six, will be a good candidate to compare. 
 

 Not sure if your caliper depth rod has a flat end, but maybe measure from the top of the scale to piston top if it does. This would give you a flat surface by holding against the scale. The deviation of different holes is the only goal.

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I ran across my Mitutoyo depth gauge today, made me think of this thread.  For the life of my I can't remember the last time I used it.  Probably the 90's.  Got it before I got married and found out I was broke, lol.

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  • 2 weeks later...
Posted (edited)

Long process of pulling the engine from the car in the woods at my father's.   Got the car up on blocks.   Had to get the blocks from the barn about 100ft away, using a dolly.   Pulling the floor jack around in soft dirt and pine straw wore me out.  Next time taking a chisel for some of the fender bolts.IMG_6913.JPG.4e40fe01832d81642c9e2f0e449372fb.JPG  

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Edited by Bryan
text was wrapped around picture.
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1 hour ago, Sam Buchanan said:

Turn those blocks so the "holes" are vertical, the way they are now can lead to failure. The blocks under the front bumper look much better.   :)

Thanks. Will do next time I'm there. I kept wondering which way would be best. Was too pooped to think straight.  Probably will go again on Monday.  I need to clear more brush, have to back a 6 1/2 x 14 trailer in there. Engine hoist won't fit on the truck.

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  • Bryan changed the title to Pulling motor in woods - warped crankshaft

Well, got the tree cut down and moved today. Tried to cut it flush to ground, but on the backside it had grown around small rocks. Started sparking.  Had to widen the path so one day I'll get the trailer back there.   

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This is the story of a very dedicated flathead-era Mopar enthusiast. Bryan, nobody can you aren't motivated. Over here I am trying to decide if it's worth my time to drive 3 hours each way in an air conditioned modern truck, to pick up a Mopar engine for under $100.  Then go for a leisurely swim in the very warm Osoyoos lake while I am there.  Stop at a few fruit stands.  Grab an ice creme cone. Maybe have the meatloaf & mashed potatoes dinner at the "Home Restaurant" on the trip back home.

 

You're making me feel a little guilty over here. Maybe as a reward for your hard work, I'll buy an extra ice creme cone for you, and eat it on your behalf.

To help keep you motived here's the lake where the engine is .😁

 

Screen Shot 2022-07-25 at 11.35.47 AM.png

Edited by keithb7
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Cool car, I like the rain drip guards over the windows .... kinda like some of those on my truck. Almost looks like a old tractor seat off to the side .... Be a cool seat for the garage if put on wheels.

 

I know you are still, cleaning to get back to the car. You do need to change those blocks.

 

My analogy of when working as a carpenter & in between jobs, I worked for a glass shop installing new vinyl windows in homes.

The old glass we would bring back to the shop & break it up into a container that was recycled.

When I had a 4'x6' piece of tempered glass, get it in the container ..... it had to be broken up to fit inside the container.

I could use my 22 ounce framing hammer & smack it right in the middle. Several times & it would not break ... usually.  It was actually pretty strong.

 

Same time the same piece of glass, stand it up in the container and lightly tap the edge of the glass, It would disintegrate into a zillion pieces.

It has a very weak spot and will break easily.

 

Same thing with concrete bricks, installed properly they have held up houses for a hundred years .... they are very strong.

 

You install them sideways like yours are, they are very weak and a simple tap from a jack stand, or a jack handle or a wrench  in the right spot  .... they can disintegrate into a zillion pieces like a piece of tempered glass.

 

The photo you show is simply a good learning tool for others on how not to block up a car.

 

We all talk about safety. About 3 weeks ago I'm digging up a dead bush in the front yard to plant a replacement. I need my 100' extension cord that's hanging on the wall behind the cherry picker & engine stand is sitting in front of it. I'm reaching for it, lose my balance and swing my right foot into the corner of square tubing.

I either chipped, cracked or broke a bone in my foot doing this. ..... Today is the first day I almost feel comfortable wearing shoes. Been soaking in epsom salt, just the weight of a blanket on my foot is painful .... been catching up on some chores .... I can not wait to get my shoes off and soak my foot again .... This is week 3 of the problem.

 

All caused because I did not want to roll the tools out of the way to reach the extension cord safely.

Sometimes short cuts can end a life, not just cause a short inconvenience  for my wife to do the shopping.

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  • Bryan changed the title to Pulled motor in woods - warped crankshaft

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