Off set grinding a cast 440 crank.

Would offset grinding a cast 440 crank significantly weaken the journals or would the chamfered edge and lower rod weight and smaller bearing surface counter the loss of material.

Would offset grinding a cast 440 crank significantly weaken the journals?
2.375" down to 2.200" and adjusting the stroke from 3.75" to 3.91" would reduce the journal overlap by about 25%


or would the chamfered edge and lower rod weight and smaller bearing surface counter the loss of material?
Have you spoken with your crankshaft grinder to see if it's possible? Without welding, you'll take 0.020-0.030" or more to get below the undercut, before you can even start start producing a fillet. Start taking off too much and you move the position of the oil holes on the journal.

Alan do you think the reduction in journal overlap would make a big difference in strength. I recently saw photos of a forged 440 crank that was offset ground to 3.85 and used bbc rods and the journals were left with a fillet, maybe some one who has done it can chim in. I'm trying to build a motor with parts I have on the shelf, one of those being some h beam rods with bbc journals.

Have a nice day

Spending $$ to offset grind a cast crank would be false economy. Your best bet for a cheap build is use stock replacement parts (rods pistons crank) so you can skip balancing and expensive machine work. If you
can find proper compression stock wieght pistons they will handle 500 hp.

We've all been there, if it's a relatively mild I doubt you'll have a problem. BBC ran a cast crank with a 4" stroke. Whether it's worth the $$$ and effort, that's entirely up to you.

You might get lucky and someone who has done it will chime in, but I don't imagine it's been done often.

Best of luck

If you really want the inches, you might be better off $$ wise to look for an aftermarket crank which would open up the opportunity for even more c.i.. That being said, I don't think a mild build would break an offset ground cast crank. I run an offset ground forged crank and have had no problems even with boost thrown at it.

Just asking but with all the cheap forged stroker kits available, why would you want to mess with offset grinding a cast crank? 440 source has kits with everything to assemble a short block for $2,300.00 If you offset grind a crank you still need bearings, rings, balancing, longer rods, and or different pistons. Add it all up, and take into consideration you are getting forged parts, instead of cast, and the kit looks pretty cost effective to me. Trust me I ponder all kinds of ways to fabricate cheap stuff to go racing, but with the price of kits, that is the cheapest dependable route.

I'm not looking to build a cheap motor, just want to use parts I already have and buy what I need. Only looking for 450-500hp and its a driver not a racer. Sure a forged crank would be better but I'm sick of seeing stuff gathering dust when it could be used. Like I said earlier, I have some rods that have 2.2 journals and are stock rb length, just need some new light weight forged pistons. jwb123 that 440 source kit at $2300us will end up being over $5000 once landed in Australia. Honestly the cost of offset grinding a cast crank doesn't bother me, its whether the cranks strength has been comprised that concerns me.

Is your crank going to be weaker? Yes

Is it going to matter in your application? Probably not

Now can you afford the cost and failure if it doesn't stand up?
I'm thinking Ma Mopar made all their BB cast cranks out of steel, not cast iron

WOW! I did not notice you were from down under. The duty increase really sucks. They did build a lot of 440's with forged cranks, I think if you can find one I would use that. Heck I tossed a couple 440 cranks the other day cleaning the shop. Nobody wants a stock crank that needs to be turned anymore. The offset grinding was something we did 40 years ago due to no cheap cranks available. I guess with the prices in your country, you are where we were 40 years ago. In my neck of the woods I don't think there is a machine shop I would trust to do the offset grinding, all the guys that did it, retired or closed shop, all the shops that can still do it would charge more than a new crank would cost. My hat is off to you for trying to do it the old school way.

can anyone make a broad guess on how many hours it would take to just turn the rod journals to the 2.20" BBC size...

Offset grinding a cast 440 crank will lighten your wallet. I wouldn't count on it doing anything else of value.

My brother is having a steel olds crank done and it's super time consuming. The stroke he wants can't be bought so this is the only way to do it.

The only thing i can add to this is,, i had a hemi crank offset ground to SBC 2.1 and had the Nitriding process done. I want to say it was 7 or 8 hundred dollars, that was 30 years ago too. lol maybe just buy a new crank my friend.

We used to offset grind 440 steel cranks 30 years ago. It wasn't super expensive back then and it was about the only option that we had. There were a few places that would build stroker cranks by welding and grinding but there weren't any local places that would do it. But that was 30 years ago. I wouldn't even think of offset grinding a steel 440 crank these days much less a cast crank. An offset ground cast crank will probably require a bunch of mallory to balance it unless the bobweight is super low. Seems like an expensive can of worms that could quickly become an expensive pile of junk.

I called a shop this morning that only grinds cranks. Cost would be $700. Guess I will be buying some new rods and leave the crank as is. I will save the 2.2 rods for the 400 stroker I build later on. What would you guys say is the hp and rpm limit on a cast crank, with light weight pistons and a typical h beam with 6.76 journals. RPM would be 5500-5800, 6000 max. I've looked at some 440 flat tops from diamond, mahle, icon, ross. They all seem to be between 608g and 660g plus pin. How would this affect the balance. Would it be possible to balance internally.

You aren't going to hurt a cast crank at 6000 rpm, especially with a lightweight piston. You can internally balance a cast crank engine if the bobweight is low enough. Probably needs to be in the 2500 range but I don't know for sure anymore. Figure out what your bobweight will be and go pay the machine shop for a balance job and then you'll know for sure. If your crank is heavy at the bobweight of your proposed parts then you'll be okay. If it is light then you'll need to find lighter parts or budget for heavy metal.

Thanks for the replies guys, I knew offset grinding the crank would not be a popular option, thought I'd ask any way. Had a look at some h-beam's today from eagle, scat, K1 and molnar. They weigh between 820g to 880g. Going to a h-beam and light piston, how much lighter than the stock can be expected. What does an LY rod and factory piston weigh.

A quick Google search found this, along with many others

https://www.forebodiesonly.com/forum/threads/440-rod-weight.11407/

I have a steel 383 mopar crank that has a Chevy off set stroke and made 850 hp.

i have a lot of offset ground stock Mopar BB cranks offset ground to BB chevy rod journal sizes for both B and RB motors, no crank failures yet . I use them in a lot of pump gas 400block stroker motors: up:
I've also had aftermarket BB Mopar stroker cranks offset ground to increase as well as decrease the stroke.
Cab
I just seen the comment on your crank being a later cast crank, not a forge steel crank. I have never had a B or RB cast crank offset ground only, forged steel cranks for those motors. Sorry for any confusion
I have had a premium new cast 360 crank offset ground to increase the stroke a little, I had it ground down the SB Chevy small rod sizes, 2.000. I haven't use it yet though

Have a nice day

On the oil holes, i have ground 440 forged cranks to 2.100 to get a 4 inch stroke. No problems with the oil holes, that 475 cube shortblock made great power, lasted a long time.