Connecting rod "offset"?

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dibbons

dibbons

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I was reading where factory Mopar small block connecting rods are "offset" and that most aftermarket connecting rods are not "offset". I wonder what is meant by "offset" and why or why not it is done. Thank you.
 
I remember an old friend of mine told me years ago that one of the tricks on a SBM was to turn the rods around the other way on the crank. Less friction I think the purpose was. Less longevity went along with the "mo power", as is usually the case with tricks and "mo power". :rolleyes:
 
It's the pistons that have the offset and not the rods. FYI
piston pin.jpg
 
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Sorry, the offset I was talking about is pin bore offset for noise reduction.
 
4spdragtop said:
My 340 rods 3418645 aren't offset
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Yes they are x2....or should be. Get a good flat surface, lay the rod on it's side, and press on the big end so that the side of the big end is pressed against the flat surface, and look at/measure the distance between the side of the small end and the surface. Then flip the rod over and do it again, and you will find a different distance from the other side of the small end to the surface. I measured some original 340 rods and IIRC got about .060" or .080" offset. It was not precisely the same rod-to-rod.

Just another reason to put the stock rods in facing the correct way.

I did not check my 1 set of SCAT rods to see if they had a similar offset.
 
dibbons said:
I was reading where factory Mopar small block connecting rods are "offset" and that most aftermarket connecting rods are not "offset". I wonder what is meant by "offset" and why or why not it is done. Thank you.
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I assume it is done on V engines as it is probably very hard to get the paired crank journal centers exactly under the centers of 2 opposite banks cylinders, simply due to the geometry of the crank versus the block and keeping the mains as wide as possible.
 
There is a thrust side, it's offset, it happens to keep the small end of the rod near center of pin boss.
You don't really want your rods rubbing/ bouncing off the pistons pin boss, you want less friction...not more.
 
Oops, i stand corrected, sorry guys.
I will have to check them now. Thanks
yellow rose said:
Yes they are. One side is further from the center line than the other.
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nm9stheham said:
Yes they are x2....or should be. Get a good flat surface, lay the rod on it's side, and press on the big end so that the side of the big end is pressed against the flat surface, and look at/measure the distance between the side of the small end and the surface. Then flip the rod over and do it again, and you will find a different distance from the other side of the small end to the surface. I measured some original 340 rods and IIRC got about .060" or .080" offset. It was not precisely the same rod-to-rod.

Just another reason to put the stock rods in facing the correct way.

I did not check my 1 set of SCAT rods to see if they had a similar offset.
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Just one of those unexpected engine design things...... I never knew it 'til I had a rod casting or 2 that looked 'squiggly' and decided to check out a full set.... whaddaya know.. they were all that way!
 
MOPAROFFICIAL said:
There is a thrust side, it's offset, it happens to keep the small end of the rod near center of pin boss.
You don't really want your rods rubbing/ bouncing off the pistons pin boss, you want less friction...not more.
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There's pin offset, which is the piston (some pistons...) and there's beam offset which is what YR and I were talking about. If you're talking offset in any rod, you're not talking about the pin end...
 
moper said:
There's pin offset, which is the piston (some pistons...) and there's beam offset which is what YR and I were talking about. If you're talking offset in any rod, you're not talking about the pin end...
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Stop confusing people as much as you are.. I said the thrust side of rod is offset. Sometimes I wonder about you.
 
I honestly could care less about what you think.
My apologies to all the contributors here for any confusion I might have caused.
 
MOPAROFFICIAL said:
If you remove just a few words you get the real message.
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No one mentioned the chamfer side has to go toward the fillet side of the crank. Not as important w/ undercut fillets I guess, but any offset going in the wrong direction would be bad.
 
No worries here. I'm easily confused but eager to learn!
Tis the season for some unknown reason.
moper said:
I honestly could care less about what you think.
My apologies to all the contributors here for any confusion I might have caused.
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Not all rods are "offset" ... The Pankl rods I have are not....004 clearance. I don't think "offset" is really what is happening here... The rods are surfaced more on one side to set the side clearances... The pins are offset on purpose to make them quieter.

1514046190985605840305.jpg
 
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Krooser said:
Not all rods are "offset" ... The Pankl rods I have are not....004 clearance. I don't think "offset" is really what is happening here... The rods are surfaced on more one side to set the side clearances... The pins are offset on purpose to make them quieter.

View attachment 1715123676
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What is being said is.. 'pertaining to the rods in question'... the thrust side sticks out more, it is offset to one side of the beam.

Say it however you wanna say it... he has no hair, no...he is bald, uh maybe he is hairless, if only I was as tall as I am long, or wide as I am fat...
 
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