I was recently given a crankshaft that came out of a 318. I do not believe it was the original one to the engine. The engine was given to my machinist and he took it apart. The motor was rebuilt but not very clean. The rods all have brand new pistons on them but they are dirty. The block doesnt look like anyone ever cleaned it. The Crank looks dirty as well.
Here is my question. The crankshaft is forged steel and has a pilot bushing in the back of it for a manual transmission. I have never heard of 318s ever coming with forged steel crankshafts. I know 273s did come with steel and of course 340s came with steel up till mid 72. I want to know if I have a 340 crank or how can I tell if it came out of a 273. I have owned 273s but dont have them anymore. There are no numbers on the crank. Any info would be helpful. The crank is .010 and .010. It looks like it will clean up good. It would be nice if it fits my 340 cause I have one that happens to just need a crank and 1 rod.

 

yes 318 had forged cranks, not all 273s were forged and not all 340's were forged.
i never found a cast crank in a 318, from 66,-78 are the 318's i had and the ones i had did in fact have forged cranks. they should have numbers.

 

some 318's had forged cranks but the majority were cast. 67 did for sure and some 68's. sometime in 68, mopar switched to cast cranks. the old poly engines had forged cranks and the bigger dodge trucks had a special truck crank that was super strong.
The 318 forged cranks (standard) were basically the same as the 273 cranks. only slight differences. the 340 was the next step up and it was stronger than the 273 crank. BUT, the 318-3 truck crank was the strongest of them all, it had the 8 bolt flange for the flywheel. I do not know how to tell a 340 crank by looking at it, I have some pictures all I know is that if you put the 340 crank next to the 273 crank, you will see a noticable difference. If you can find a number on it, might help.

 

I'll look through some of my old books....

 

There are no numbers on the crank at all. I have an original 1969 340 crank that I thought was junk from rust but I am pleasantly surprised that the rust is not nearly as bad as I though. I beed blasted the crank and was able to polish the journals out to a shine with no pits or visable marks at all. The 340 crank looks a bit different. The other alleged 318 steal crank is a 6 bold crank. I will take a picture tomorrow and post it.