Copper rods and now undersized crank bearings?

[John Hogan]

The 73 RR 340 that I purchased had about 110,000 miles on it. Seller told me that the original owner told him the engine was untouched since purchased new. It is a #matching block to the car. Well, the copper rods I posted about earlier were obviously factory, but I found the engine to have Federal Mogul -20 rod bearings and -10 main bearings. The pistons appear to be stock with no markings other than the cylinder number stamped in each piston.
The engine stamping on the front of the block appears to be :
J 340 R 4163919 +
70 71
Since my 30+ year ago engine building days were "build 'em and run 'em" before the days of internet research, I'm not sure if I'm crazy or normal being so curious about the story on this engine. Is it possible it shipped from the factory with undersize bearings along with the three copper rods?

 

[toolmanmike]

Copper rods were common. -.010 under bearings probably not. But never say never. They might have used up a crank that was mis machined from the start. I have seen 1 and 2 under bearings that were used for proper oil clearance.I don't see a date on the bearings like oe bearings have.

 

[R/T Boy 67]

It looks to me like it has been apart. The pistons are stamped with the cyl. numbers, and the 7071 looks like a rebuilders' stamp to me.

 

[MIKESPOLARA]

I don't think factory stamped the piston number

 

[Fran Blacker]

Don't think factory would use a -.020 crank. Bearing last looks spun to me.

 

[Lefty71]

No date on the bearing? Or is that a "code"??
Why worry about any of it?? None of it really affects the value of the car?
It made it 110,000 miles one way or other.

 

[John Hogan]

It looks to me like it has been apart. The pistons are stamped with the cyl. numbers, and the 7071 looks like a rebuilders' stamp to me.

Yep, my guess is that something happened that spun a couple of bearings and crank was turned and the bottom end was rebuilt with using the same stock pistons. Not actually a deal one way or the other, just made me wonder if the original owner gave the guy I bought it from "never been touched" line, or if the guy I bought it from had it redone.

 

[John Hogan]

No date on the bearing? Or is that a "code"??
Why worry about any of it?? None of it really affects the value of the car?
It made it 110,000 miles one way or other.

Agreed, it was just a curiosity thing. Bearings appear to have the old Federal Mogul logo on them.

 

[John Hogan]

Don't think factory would use a -.020 crank. Bearing last looks spun to me.

Just a bad picture,crank, bearing and rod are fine. Going to end my curiosity and just build a motor

 

[GTX JOHN]

The Mopar engines in the 60s/70s had a Maltese cross on the ID pad if
they had one or more journals undersize from the factory.

It was quite common on the 426 Hemi, especially in 1966 the first year of'
the Street Hemi.

It does not hurt anything as long as you are aware of it!

 

[Kern Dog]

You really need to cut your fingernails.

 

[moparedtn]

 

[John Hogan]

You really need to cut your fingernails.

View attachment 1520777

The right length for checking cylinder ridge !

 

[66fs]

I always got rid of the copper rods. Copper was a poor band aid.
I have seen 340's with factory undersize bearings. Forged cranks were premium shot peened units and I assume the cast 340 cranks were premium also like the mid 70's HP 360's with a CFD casting and also shot peened. Someone has been in that motor.