Did the factory drill this balancing hole in the crankshaft?

[dibbons]

Never saw a hole in the crank that perforated the side before.

 

[dibbons]

And this grinding is taken off of two sides of the same crank throw. Is that normal or unusual?

 

[ssba]

That's how they make em.

 

[krazykuda]

Yep, that can happen in the manufacturing at the factory...

 

[yellow rose]

The cranks are mass balanced.

They ain't pretty.

 

[65Val]

With this question and the squirt hole thread, I need to ask if this is a rebuilt engine, or one thats been together since day1? The squirt hole being on the side it's on, looks as though, if it has been rebuilt, that they used the old speed secret of swapping the pistons and rods bank for bank because of pin offsets to make that 2,3 or 4 horsepower that you might gain.

The grinding on the crank might be the shop's balancing at rebuild time.

 

[dibbons]

The motor is .040 over, has a '73 build date, a 340 '68 intake manifold, '71 440 low performance AVs carb, a front sump oil pan. a '69 and older water pump. It appears to have a forged crankshaft, which I don't think was available in a 340 in 1973. The pistons are flattops with four valve notches and a notch to mark the front. The camshaft seems to have had .501 to .508 of lift, if I measured it correctly.

 

[65Val]

...so it's definitely been apart at least once. The number/symbols will be on the other side of the rod/cap, and the last machine shop switched the pistons/rods/caps bank for bank to get that very small HP gain.

 

[Inertia]

...so it's definitely been apart at least once. The number/symbols will be on the other side of the rod/cap, and the last machine shop switched the pistons/rods/caps bank for bank to get that very small HP gain.

When you do the "speed secret" swap from bank to bank, the squirt hole remains pointing toward the camshaft, and the bearing chamfer remains correct in relation to crank.

That rod is in the right hole, #5, and if that is a factory "pee hole" then it is certainly in backwards.

I wonder which way the pistons pointing?

good eye and good catch. ! ! !

cheers.

 

[dibbons]

All the pistons notches are pointed to the front.

 

[Mr Gorsky]

Hey Dibbons....don't be shy doling out the likes.

These guys have helped you out. Costs you nothing to click.

 

[yellow rose]

Some 73's got through with steel cranks.

I had a numbers matching 72 that had 2.02 valves.

They used what that had until it was gone.

 

[dibbons]

Maybe because it has a block with a date of 9/71 cast on the side it received a forged crank, otherwise someone swapped it in, (Just like they did the intake manifold, water pump, carburetor, air cleaner, etc.)

 

[krazykuda]

Maybe because it has a block with a date of 9/71 cast on the side it received a forged crank, otherwise someone swapped it in, (Just like they did the intake manifold, water pump, carburetor, air cleaner, etc.)

It could have been built one year (72) and then sat in a warehouse until the next model year (73) and used up then...

 

[crackedback]

It could have been built one year (72) and then sat in a warehouse until the next model year (73) and used up then...

Not likely, the build date on the engine was in 1973 IIRC. He posted the digits from the front of the block.

The engine is a mutt. It came with a cast crank and now has a forged unit.

 

[dibbons]

Does anyone know if those are factory style pistons (low compression I imagine)? See post #7 for foto.

By the way, assuming the 10000 calendar code on the block is really 04238, then according to a website that has a decoder, the motor build date would have been March 5, 1973.