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Stock 218 Rod journal size


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you have posted the measurement already, however as an added.....Motors repair manual of the era state the actual journal as 2.0615 - 2.0625..so in actuality there is an acceptable difference of .001....when built at the factory it is per my reading the book that if the journal was on the smaller size the corresponding insert would be .001 difference for this allowance and will be stamped as M1 is this pertained to the main or R1 if this pertained to the rod...

Edited by Plymouthy Adams
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2 hours ago, 5027 steve said:

So in actuality the factory had no clearance on the rod journals....I listened what the book said was bearing size ....and your telling me the journals we're the same size ..... Thanks for the quick response........Steve

 

There was factory clearance at the rod journals. There needs to be clearance otherwise it wouldn't spin. Per the manual the clearance should be .0005"  - .0015"

Therefore, for a STD journal size would be 2.062 to 2.061"

If it's been ground .010" under, then 2.052 to 2.051".

You can keep subtracting for every .010" thereafter...

 

2 hours ago, Plymouthy Adams said:

bearings are sized to proper tolerance for the journal they are designed to fit.   

 

Journals are sized provide the correct clearance for the bearings that will be used.

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3 hours ago, John-T-53 said:

 

There was factory clearance at the rod journals. There needs to be clearance otherwise it wouldn't spin. Per the manual the clearance should be .0005"  - .0015"

Therefore, for a STD journal size would be 2.062 to 2.061"

If it's been ground .010" under, then 2.052 to 2.051".

You can keep subtracting for every .010" thereafter...

 

 

Journals are sized provide the correct clearance for the bearings that will be used.

bearings are sized to the journal not the other way around...

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It's a mutual relationship...

 

I'm not sure how you'd size a bearing other than selecting a particular size from a parts dealer. They are not modified in thickness. Sometimes shimmed, sometimes trimmed at the edges (custom applications mainly).

 

By sizing a journal I'm talking about grinding and polishing (on a crank grinding machine).

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a  machine ship will grind the journal to stock if built up and returned to standard.....they will go in exact increment undersize from there....the bearings are made for the journal as per the specification of the BLUEPRINT from the original builder.....IF however you micro polishing a journal that may be a bit work...you can get special bearings to take into account this usually in .001; .002 ; or .00 and then for under size of .010 and appreciative wear from there....012.  I would not want/pay a machine shop to  just polish journal to a random mixture of measurements....

Edited by Plymouthy Adams
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"a  machine ship will grind the journal to stock if built up and returned to standard....."

 

I was referring to grinding to the next step undersize. Cranks are readily available for our flatheads so I would not recommend welding all the journals on a crank to bring it back to STD. It's easier to get a less worn one if your crank is garbage. Besides, by the time it gets up there towards the wear limits you are usually dealing with cracking and other flaws. If it just has one bad journal, though, that's a different story. Or if you have a rare crank...

 

"they will go in exact increment undersize from there....the bearings are made for the journal as per the specification of the BLUEPRINT from the original builder....."

 

Correct as stated previously. .010" under, .020" under, up to .050"...and the bearings are harder to find as you increase thickness.

 

"IF however you micro polishing a journal that may be a bit work..."

 

Nobody would attempt using a polishing machine for removing that amount of material. If attempted, the journal would be out of round and the side radii not right. Polishing is just the final step after grinding. It might remove a few tenths (.0001) at the most, but you have to use the right belts.

 

"you can get special bearings to take into account this usually in .001; .002 ; or .00 and then for under size of .010 and appreciative wear from there....012."

 

I have not heard of undersize bearings (for our engines) available in increments of one thousandth of an inch, just increments of ten thousandths.

 

"I would not want/pay a machine shop to just polish journal to a random mixture of measurements...."

 

Why would you want that anyway? I'm sure that most shops are not dumb enough to do this and would educate any customer requesting it. Cranks are ground so that all journals are the exact size. Rods are honed in the same manner.

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I more or less agree; just the quoting and terminology is getting skewed a bit here. I didn't say that a machine would size a bearing...I don't know what that means. Can we still be friends?

 

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Oh I thought we were just talking about rods? LOL

 

From my experience I would think this is a rare practice...usually done in .010 increments from my experience. I'm actually heading down to the machine shop this afternoon and I will get their input.

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And all I wanted was a measurement so I could take to measuring mine LOL .....very interesting that Dodge never published the stock size of the Rod Journels....I figured someone would look in a book and answer....But Very interesting responses that's for sure...... Thanks Guys ........

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26 minutes ago, 5027 steve said:

And all I wanted was a measurement so I could take to measuring mine LOL .....very interesting that Dodge never published the stock size of the Rod Journels....I figured someone would look in a book and answer....But Very interesting responses that's for sure...... Thanks Guys ........

 

that was exactly what I did for you...….

  • Thanks 1
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