Difference between the B crank and R/B crank

[70RAGTOPR/T]

I know that there is a difference between a B crank and a R/B crank but I never seen both of them side by side.  Since I'm going to Carlisle in a month I was thinking of picking up a R/B crank for my B block.  How can I tell the difference between them?  Does any one have any pics of both?  Also, what should be the $$$ of a R/B crank?  I want a crank from the late 60's to the early 70's.  Thanks for your help in advance.

[Killer_Mopar]

Kind of hard to tell the difference by just looking. The easiest way is to measure the main sizes, B crank mains are 2.625 and RB mains are 2.75.

[moper]

There's a few small differences. The stroke is bigger, the mains are bigger on RBs. That's probably the easiest way. Arrive with a vernier caliper, and measure the mains. That way, you know if it's been turned too. 2.75" is R/B, and will be 3.75" stroke, have 6 bolts in the rear flange, and can be cast or forged. CAst will have "440" cast into them, and be a duller greyish/brown if dirty. Forged will have a wide parting line (where the 2 halves of the original mold came together) and the counterweights will be a brighter silver, even when a little grungy. B will have 2.625" mains, and will be 3.37 stroke, 6 bolt rears, and either be forged (383 versions) or cast (will say "400" on it, and be larger counterweights). 8 bolt RB's do exist..Hemis came with them, as did early 413s. IMO, stay away from anything turned undersize, that has a mark on it anywhere, and stay away from used fueler and hemi cranks. If you have to pay more than $175 for a forged unit, rethink the purcahse. If you are building a 440, you can always use a cast crank, but any stroker should go forged for balancing and fit issues. Cast 440 cranks are cheap. Like $50 cheap, but may cost more to balance (hence th no stroker deal...)

[Challenger6pak]

I have this table.  Maybe someone has a clearer one.  These are casting #'s. I am unsure if they are printed on the crank or not.


Crank # Engine Type Application
(1521 436) 413 Forged Truck 8-bolt crank
(1737 642 )350, 361, 383 Forged

1851 127 413 Forged 59-64 Car
1851 436 413 Forged 60-77 Truck 8-bolt crank
1855 527 383 Forged 59-61 Car
1978 698 RB Forged 59-61 Car
2203 155 B Forged 59-61 Car
2206 157 361 Forged 60-78 Truck 8-bolt crank
(2206 158) 440, 426 ,413 Forged

  
(2206 159) 400 383 361 Forged



(2206 160 440) 413, 426  Forged



  
2402 330 426 Forged 63-64 Max Wedge
2463 548 426 Forged 64 Max Wedge, 8-bolt crank
3462 923 383
400
 Cast
Cast
 69-71 2bbl
71-78 Car, 73-79 Truck
 
3751 877 400 Cast 73-78 Car, 73-79 Truck
3751 888 440 Cast 73-78 Car
4027 172 400 Cast 73-78 Car
4027 175 440 Cast 73-78 Car, 73-79 Truck

[Chryco Psycho]

cast cranks often have the part # but steel cranks never do

[67Vette427]

A lot of good information here. Right on the description of the two also!

The only thing I wanted to add is I bought two used 440 forged cranks and both had minor cracks. I wouldn't pay too much unless they had proof it was checked for cracks or would refund it if cracks were found. From now on I'm buying a new forged. 

I went out and moved the car and pulled my 440 cast crank out from under the bench and took some pictures. Everybody has been pretty helpful to me here so here you go... One cast crank.. I'm going to sell this one if anybody is interested..

[70RAGTOPR/T]

Thanks vette for the pics.  I'll take the pics to Carlisle when I go.

[67Vette427]

You're welcome! Glad you can use them. Here's a pic of a 440 steel crank in the block. I've high lighted areas of difference to the cast. I have a 383 coming back next week. I'll get some of it for you.