From what I have seen early 72 are forged and later ones are cast.Besides, 72 would have most likely been cast from new.
From what I have seen early 72 are forged and later ones are cast.Besides, 72 would have most likely been cast from new.
Remember, the 273 and early 318 had the much lighter rods, so that's probably why the 318 crank was not drilled and the 340 crank was.
Pistons were lighter too.
Tap them with a steel hammer; the forged ones will ring with a long decay time. The cast one will thud
The one on the left looks cast.But I haven't seen a teener drilled , so I'm guessing it's a cast 340
The one in the center has a wrong sprocket on it for a 340, and a closed throw, so I'm guessing it's an early 318
The one on the right has a 340 sprocket on it, and is drilled so I'm guessing it's correct for an early 340.
I noticed that one of my cast 318cranks also rings, but the decay time is a lot shorter just as you describe. Yeah maybe thud was a poor choice of words; I just meant deader than the forged units.I have cast cranks and forged cranks and 1 cast crank with a narrow parting line rings nice, not as loud or high pitch or as long as a forged crank. If you have a crank that goes thud it is cracked.
also the thicker counter weights have a lower pitch and don't ring as long
Just to be clear these cranks are made from a steel billet and forged into their rough shape then machined... no castings or iron are involved.Might have to do with the crank castings themselves. Or the material. Better iron is heavier. I'd say it's probably balancing issues but that's a total guess.
The pilot hole is a different size on earlier cranks... the change was made around '68 IIRC. The flange is about the same. Someone here will have the exact date.On the early 273 cranks, The flange on the back is smaller for torque convertors I believe. Not sure about the early 318?
Actually, the initial step of a forged crank is to cast the initial rough shape; the next step is to use the forge to force it into the final rough shape prior to machining.Just to be clear these cranks are made from a steel billet and forged into their rough shape then machined... no castings or iron are involved.
The forged 340 will be stronger but the general agreement is that the cast cranks (318, 273) will take 400 to 500 HP.Another question. Is it better to use a 318 crank in a 340 if you use the new light weight pistons and I good new I beam rod?
Nope... the cranks start as a round steel billet heated to white hot then hammered into shape... some are twisted some are not.Actually, the initial step of a forged crank is to cast the initial rough shape; the next step is to use the forge to force it into the final rough shape prior to machining.
Thanks, interesting video. Looks like there is more than one process....
From what I know from years hauling steel an ingot is a piece of material that will be melted and used in the production of a final product. A billet is a large round bar or square bar ready for machining or forging.What that video calls a billet I call an ingot. When most people speak of a billet crank it's meant as a machine round bar that is machine finished.