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Connecting rod for 31’ needed #403433
02/12/18 05:01 AM
02/12/18 05:01 AM
Joined: Sep 2014
Posts: 1,726
Dartmouth MA
C
Chistech Offline OP

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Chistech  Offline OP

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Joined: Sep 2014
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Dartmouth MA
I’m looking for a remanufactured rod (NORS) for a 29-31 engine, .020 undersized. Prefer a Perfection brand rod if possible to complete a set of 5 I have. Needed for a rebuild.

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Re: Connecting rod for 31’ needed [Re: Chistech] #403438
02/12/18 02:20 PM
02/12/18 02:20 PM
Joined: Jul 2008
Posts: 699
Lawrenceville, GA
Dave39MD Online content

Oil Can Mechanic
Dave39MD  Online Content

Oil Can Mechanic
Joined: Jul 2008
Posts: 699
Lawrenceville, GA
I have a few boxes of recon rods but will not be in the shop for a few days. When back I will check if you have not found it by then. Some are perfection, some Thompson as I recall.

Dave

Re: Connecting rod for 31’ needed [Re: Chistech] #403441
02/12/18 02:34 PM
02/12/18 02:34 PM
Joined: Jul 2008
Posts: 699
Lawrenceville, GA
Dave39MD Online content

Oil Can Mechanic
Dave39MD  Online Content

Oil Can Mechanic
Joined: Jul 2008
Posts: 699
Lawrenceville, GA
If your rods are still in boxes the part number and other numbers on the end flap would help.

Re: Connecting rod for 31’ needed [Re: Chistech] #403442
02/12/18 03:41 PM
02/12/18 03:41 PM
Joined: Nov 2001
Posts: 28,717
Eagle Point, Oregon
Junkyard Dog Offline

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Junkyard Dog  Offline

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Eagle Point, Oregon
You will also want the rod to weigh near the same as the other 5 rods in case you want to have the engine balanced.

laugh wink beer2


The Mangy Old Mutt

"If It's Not Junk.....It's Not Treasure!"
Re: Connecting rod for 31’ needed [Re: Chistech] #403455
02/12/18 09:07 PM
02/12/18 09:07 PM
Joined: Sep 2014
Posts: 1,726
Dartmouth MA
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Chistech Offline OP

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Chistech  Offline OP

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Joined: Sep 2014
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Dartmouth MA
Here's what I have:

5 Perfection rods # RR3415 .020 US

All mike out at 1.979 give or take .001

Weights: 1.992, 1.942, 1.882, 1.878, 1.832 There is a .160 maximum spread between the 5 or 2 3/4 ounces. That sounds like a lot to me. I would be willing to trade with others wanting to balance out sets for themselves. Not sure how material would be removed to lessen the weight as I'm not an engine machinist but I'm sure they have ways to do it. What's amazing is the difference from years ago to now. The Ross pistons I had custom made for my Olds don't differ in weight by more than .4 grams! Crazy how things have changed.

The other Perfection rod I have is part # RR3412
Weight: 1.894 Size: 1.998 (standard size I believe)

Re: Connecting rod for 31’ needed [Re: Chistech] #403461
02/12/18 10:34 PM
02/12/18 10:34 PM
Joined: Jan 2002
Posts: 25,143
West Allis,Wi.
Chev Nut Offline

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Joined: Jan 2002
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West Allis,Wi.
I found that The old model connecting rods differ greatly in weight.
There were installed in production engines selected by matching weight up tp 1/10 of an ounce. Same for pistons......and other GM engines years ago.


Chevgene
Re: Connecting rod for 31’ needed [Re: Chistech] #403466
02/13/18 12:30 AM
02/13/18 12:30 AM
Joined: Nov 2001
Posts: 28,717
Eagle Point, Oregon
Junkyard Dog Offline

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Junkyard Dog  Offline

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Joined: Nov 2001
Posts: 28,717
Eagle Point, Oregon
Quote
Not sure how material would be removed to lessen the weight


The material on the rods is ground away to achieve the correct weight for balancing purposes. The less that has to be ground away the better. All of the rods should weigh almost the same, if not the same, as the lightest rod.

laugh wink beer2



The Mangy Old Mutt

"If It's Not Junk.....It's Not Treasure!"
Re: Connecting rod for 31’ needed [Re: Junkyard Dog] #403468
02/13/18 01:07 AM
02/13/18 01:07 AM
Joined: Apr 2006
Posts: 2,047
San Leandro, CA
Rustoholic Offline
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Rustoholic  Offline
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San Leandro, CA
I experienced a difference in weight of the rods I used in my '28 engine rebuild.

Here's a link to a series of posts that describe how I sanded material off of some rods so they weighed the same as the lightest one. Rod balancing for a '28 rebuild

Cheers, Dean

Re: Connecting rod for 31’ needed [Re: Chistech] #403470
02/13/18 02:45 AM
02/13/18 02:45 AM
Joined: Sep 2014
Posts: 1,726
Dartmouth MA
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Chistech Offline OP

ChatMaster - 1,500
Chistech  Offline OP

ChatMaster - 1,500
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Joined: Sep 2014
Posts: 1,726
Dartmouth MA
Tonight I weighed the rods that were in my running engine and found them all pretty close with a difference of .0160 between the heaviest and lightest. 5 of them have newer babbitt in them and have .012 worth of shim on both sides. One was original and has .003 of shim on one side only. If I can trades some rods with people or make the other 5 and one of these from the Perfection rods, I'll try to do that. I'll see what the machine shop says. Hopefully someone might have some rods and be will to trade to even the weights off. It would be a win/win I believe.

Dean, thanks for the info and link to your thread. It will come in very handy once I know more about the outcome of the crank and block.


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