I'm curious what people consider the better approach re: whether to upgrade my RB 452's crank since (yet another change of direction) it'll be going back together w/ the CNC Victor heads and a street roller cam. My original plan was to put the .010 / .010 OEM forged piece that came out of it back in, since it passed the magnaflux and the journals polished OK w/o having to be cut down again. The block is .060" and is otherwise getting a fresh set of rings & bearings. This is INTENDED to be the last time I go through this bottom end, since I've picked up pretty much all the parts needed to assemble a fresh spare 448 short block.

However, I expect the change in heads and cam could add another 40 HP, pushing the engine up close(r) to the 650 HP range. I've got a "blem" Eagle 4340 piece I picked up to use w/ my 448 backup... should I use that, instead of the OEM crank, for a bit of added insurance at the higher power level? If so, then I'll have to factor in picking up another 4340 crank at some point in order to finish the 448.

Yep, just another one of those decision points in the process flow of getting my junk back together.

IMO you will brake a stock block before you will a stock forged crank

I don't know if some years / batches of OEM forged cranks were better than others (I do know of some cracked / broken ones), but this one seems to be a survivor of sorts. I really did expect it to fail the magnaflux the last time, but it's still solid.

Personally, I'd use the stock crank.

I bet if you send that crank (stock) off you will find a buch of small cracks. can't tell you how many stock cranks I have had to go through to find a good one.

yea magnuflux will help to find the cracks you can see. glow light has deflated my balloon a couple times.
Now small stress fractures in some places are just fine.

But stroke it and be happy

I thought the blemed eagles where just .010 so can't sell as new / perfect.

This particular blem Eagle is .010" on the rods, std on the mains.

Are you saying a magnaflux doesn't reveal cracks and another type of inspection is required to determine if a cranks is usable or not?

mangnaflux only seem to show up open cracks better. Glow light shows all cracks even small stress cracks.

If it were mine the 4340 crank would be going in, no question. With a new roller cam and the new Victors you'll be seeing 7000 rpm routinely i would think.

I have an Eagle blem in the 572 and it checked out fine when Dwayne assembled the motor.



Ron

I would build the higher power engine with the Eagle crank, and put the checked factory crank in the spare/back-up motor. If the factory crank is already balanced for the 452, use that block for the back-up and put the primary/higher power setup in the 448 block. No sense in rebalancing for 4 CID.

IMO, the factory crank is good to use. But it will need to be magnafluxed on a regular basis to be safe. So depending on use, once a year or so (maybe 2 years for you since you don't run it very much).

Yeah, the OEM crank is already balanced for the 452 assembly. The Eagle crank is OOB and unbalanced for anything at this point. And I'd consider assembling the 448 fresh w/ the Victors, except I still need to deal w/ the old style aluminum main caps, detail the block, etc.

The 452 is closer to being ready to (re)assemble and is the PLR (Path of Least Resistance). But it's got a shorter life expectancy...