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Old 01-30-2020, 03:05 PM
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Default used cast pistons & FUBAR stock rods ...sell or wall art?

First....I have no history on this 455 (.030) and I bought it complete as a core to rebuild.
I could rotate the Harmonic Balancer with the spark plugs removed so I pulled it apart and I did not see anything unusual other than the cam lobes and a few lifter showing some wear. Crank and big end rod bearings were std/std with some copper staring to show on several... but nothing alarming. When I popped the pistons/rods out I found every rod had a cut (think hacksaw) 90 degree across the rod just North of the big end. there are some pics here to see the cuts. Each rod/cap pair was stamped 1-8 so the cut was not to identify location.
Anyway.......I am going with a .040 overbore and new pistons/rods. Is there any value to the .030 cast 417NP used pistons? If so, should press out the pins and discard the rods (less weight to ship just pistons). Or am I looking at wall art to hang in the garage?

I have learned alot from PY and I am sure I will be enlightened once again with your responses.

Dave
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  #2  
Old 01-30-2020, 03:16 PM
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Were all the cuts toward the chamfer side of the big end?

Oh the good old days of my youth ... I woulda used those old parts and driven the car another 30,000 miles

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Old 01-30-2020, 03:40 PM
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I rebuilt a 1970 350, out of a firebird, and it is in my car now, stock std. pistons, the block had about .004-.006 wear. I needed an engine to "temporarily replace the original 400, with a flat cam lobe (temporary is taking too long, the 350 is still in my car, NOT MUCH LONGER!!!)

Anyhoo, the stock rods in the 350 had those cuts on them, also. I wonder why also. I know the engine had never been apart...

Put those parts up for sale, here. do n't do a thing to them! You never know who might be tickled to buy those...The pistons are not perfect, but could be used in an economy build...Ask $75.00 for them!

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Old 01-30-2020, 06:35 PM
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One word comes to mind: SCRAP...

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Old 01-30-2020, 10:13 PM
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Those cuts are a perfect stress riser leading to cracks and total failure. I can't imagine anyone--especially Pontiac--putting them there intentionally; although that's apparently what happened.

Wall art; or scrap to be melted down.

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Old 01-30-2020, 10:53 PM
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Pictured skirt is tore up and probably doesn't have any taper left. Very strange that someone would purposefully cut a rod like that.

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Old 01-31-2020, 07:06 AM
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Those cuts in those Rods are a buil in guaranteed failure!

Stock Rods in regards to a 455s stroke with the stock recipercating weights involved are under over 7800 lbs of tension at 6000 rpm when there snatched from TDC and those cuts are right where the rod would fail!

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Old 01-31-2020, 09:21 AM
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Can't find it but I swear there was another thread a while back showing rods with cuts exactly like these.
This is perhaps the same engine or some kind of conspiracy...

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Old 01-31-2020, 09:30 AM
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Evidence of a rude Machine Shop process.

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Old 01-31-2020, 09:48 AM
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Factory red line enforcement............

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Old 01-31-2020, 09:56 AM
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Donate them to someone that will make car show trophies, lamps or some kind of "Junk Art" out of them.


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Old 01-31-2020, 09:57 AM
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Quote:
Originally Posted by firechicken View Post
Can't find it but I swear there was another thread a while back showing rods with cuts exactly like these.
This is perhaps the same engine or some kind of conspiracy...
Exactly! Those cuts are identical to what was posted here a year or two ago!

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Old 01-31-2020, 11:20 AM
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The people that killed Kennedy were after Pontiac rods too? Lol

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Old 01-31-2020, 12:22 PM
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Maybe a few batches of rods were made during some labor dispute at GM

I bet the rod bolts would let go way before that rod would break at those cuts. Pretty meaty in that area.

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Old 01-31-2020, 02:06 PM
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Quote:
Originally Posted by Half-Inch Stud View Post
Evidence of a rude Machine Shop process.
I've seem um before on factory rods. So suspect you're right. Something to do with mass production/machineing.

Clay

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Old 01-31-2020, 06:01 PM
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Quote:
Originally Posted by firechicken View Post
Can't find it but I swear there was another thread a while back showing rods with cuts exactly like these.
This is perhaps the same engine or some kind of conspiracy...
http://forums.maxperformanceinc.com/...d.php?t=828300

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Old 01-31-2020, 07:15 PM
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Quote:
Originally Posted by dataway View Post
Maybe a few batches of rods were made during some labor dispute at GM

I bet the rod bolts would let go way before that rod would break at those cuts. Pretty meaty in that area.
I’d think those rods in a 455 would have great potential problems, not as much in a 350.

All the attention to details we give folks here, you’d think that engine would have grenaded when first fired up at GM...no way that thing could last....

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Old 01-31-2020, 07:53 PM
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Quote:
Originally Posted by dataway View Post
….I bet the rod bolts would let go way before that rod would break at those cuts. Pretty meaty in that area.
I agree... yes, those are "notches" that will create stress risers but if you "radiused" them I doubt the section loss would be enough to make them a lot weaker.

IMO if you extended the factory-machined edge as shown there would be no issue:

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Old 01-31-2020, 10:41 PM
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I guess I am getting a bit senile.
I forgot that I posted this subject when I first took the engine apart in the Spring of 2019.

  #20  
Old 01-31-2020, 10:43 PM
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now that is a different approach to the problem. Followed by Shot Peening to de-stress?

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