I called a guy about his BBC for sale and he said that crank was once a Chrysler that was turned .010/.010 and it's now a "std/std" in his BBC. I did some studying and found out that the Chryslers have a 4.800 bore spacing where as the Chevy has a 4.840, if that's correct or not, I'm not sure? But, is that possible? Does anyone know how Chrysler numbered their blocks and/or the firing order? Has anyone heard/done this before? Thanks, Randy
While I don't know about this particular situation, it is possible to fit some cranks into other engines. Before stroker cranks were as common as today there were cases where a crank from one engine became a stroker crank for another.
that doent mean its the right thing to do. I dont know if its possible to do but like I said, sounds like someone was pulling your leg.
It might be possible to make the crank physicly fit the block, but I think that would be your limit. You would probably need custom made rods, as I doubt crank throw would be the same, possibly even pistons if the rod angle was off too far as well. Thrust surfaces are probably different. Custom cam would be required if the firing order was different (Im not too familiar with Chrysler engines). Rear main seal and timing seal would most likely be custom made too. Then you have balancing issues (external vs internal, not sure what Chrysler did), which also tie into what flexplate/flywheel you need to use, and can you make it tie into a transmission? With a flexplate you could probably just drill new holes, but I bet matching a clutch/pressure plate/throwout bearing/fork/and the pilot bearing in the crank to the transmission shaft would be tons of work. Also, the timing chain and crank sprocket would be fun to figure out. Lastly, the front pulley probably would need spacing to get it to line up with the BBC accessories. Sounds like someone realized what they got themselves into, and are trying to pawn off thier headache.
I was once told that older forged stroker cranks for the mopar RB motors use the same core as big block chevy. I cant remember where I came by this info, or if its reliable.
My 557" K/B Hemi is running a Bryant crank 4.615" stroke Chebby crank with the correct flange on it . Makes 874 HP . Must work !
BBC aftermarket cranks easy to get and priced better than other makes in the aftermarket. Many aftermarket cranks have standardized to Chevy parts (rods) and many rods use chevy pins to allow for better options on custom pistons. Id stay away from this engine unless you could see it run, this may have been a racer/ machinist trick before stroker cranks were available, it may work, but I would want to see it run.
It takes MAJOR amounts of machine work to put a BB Mopar crank in a chevy or vise-versa. You have to deal with the flange on the end of the crank, weld up and machine a new thrust surface, and also deal with the nose of the crank. They do have a common main journal size. The real question is why? The 440 crank is 3.75 stroke, the 396/427 is 3.76. The crank pins are larger on the 440 crank, so someone will probably try to make the case that you could use the 440 crank to to an offset-ground stroker, yea you could drop around $1500 on machine work to correct the problems with the thrust surface and crank flange and offset grind the 440 crank, or you could just buy a 4" stroke 454 crank, wash it and drop it in. Ok, so how about if you had to de-stroke it for comp eliminator? Use a 348 crank like Bernie Agaman did in the late '70s, when he was building smaller BB's for Pro Stock, its virtually a drop-in. Or offset grind the BB crank to small block rod journals. As far as "Chryco", if what you are saying is that Bryant started with the same raw forging that they use for BB Chevy cranks, yea, I'd buy that. But unless that raw forging actually came from chevrolet, its not really a chevy crank until its machined, is it? And if its a question of starting from a "chevy" billet, well thats not a chevy crank at all. Its a coincidence that my "bullshit" comment appeared directly under your post, your post hadn't appeared when I started typing. It wasnt in response to your post.
Bore spacing is from one bore to the next. So with 4 bores lined up, there are three "bore spacings", meaning that the difference is a minimum of .120 over the length of the engine, or .060 from the middle to each end
Not possable at all, The main cap placement and bearing size thrust location would make this a welding and machining nightmare... complete udder BULLSHIT!
Wow, lots of posts saying "it isn't possible". Others saying "it is possible (with a ton of machine work and welding) but just plain doesn't make sense". Almost all of the posts do agree on one thing though ... stay away from it. I agree with Bulldog in that I doubt it truly has a crank that was originally from a Chrysler ... BUT ... that IS what the original post states. The original poster does not state the intended purpose for this engine but I would stay away from it. There is something to be said for being able to purchase rods, cranks, pistons, rings, bearings off the shelf, that simply need to be washed and installed in the event of an engine failure or freshening ... I wouldn't feel comfortable with this engine unless I was the orginal builder and knew exactly what parts and machine work was required to build this thing in the first place. If the present owner/seller is incorrect regarding the "Chrysler crank install" or is incapable of explaining exactly what he means, what else has been done to that engine that he does not know about or can't accurately explain.
I don't know, but want to say that when guys made 4"x4", SBC's years and years ago before the 327 became King, they used massively reworked Stude cranks. I have never seen this documented or talked to anybody that's ever done it so flat don't know if this is so or not. pdq67
For those of you that think it's impossible to machine a crank from one engine to fit another; someone needs to tell Moldex(a custom crankshaft company) because they have done it for several different engines. There are probably even more interchange possibilities if you start with a raw casting/forging.
But the engine in question IS a BBC, so why would you have to do anything to run BBC rods? It wouldn't make a lot of sense to spend beaucoup $$$ to put a Chrysler crank in a BBC, just so you can run BBC rods. I think BBC's came from the factory with BBC rods......
why go thru all the trouble. Stroker cranks are readily available that drop right in with no machining needed. Cheep too.
If he had said the crank pins were machined to chevy size, and the crank was in a 440 Mopar I dont think ANYONE would be giving any debate here, common practice. Swapping cranks between BBM & BBC? One more time, with feeling...BULLSHIT. And yes, 292 Y-Block cranks used to be re-machined to use as strokers in small-block Fords, at that time, there was no other choice. What this has to do with using a heavily machined, 3.75 stroke Mopar crank instead of a common, cheap 3.76 stroke 396 crank ecapes me.
Ya know, I kinda promised myself I was gonna sign off on this mess, figured I had pretty much said all that needs to be said anyway, but when you go back and really read what the guy that owns this thing is quoted as saying, it gets even better! Since when does 2.375 (BB Mopar rod journal) -.010 equal 2.2?? The guy cant even do math for gods sake. Run far and run fast!
The only thing I can think of is that maybe this was done a long time ago, and the Mopar crank was lighter than the Chevy crank, and would therefore rev quicker and higher. That's purely speculation on my part though. I do know that before stroker cranks were an 800-call away, and machine shops were really "machine shops" and not "assemblers," putting a Chevy crank in a 440 mopar was a good way to get a lot more cubic inches. One of my mentors had that combo in his '70 Challenger, with Max Wedge heads and a sheetmetal tunnel ram. I THINK it was 496ci, but I'm not sure... it's been 20 years. Stude crank and Buick 322 rings used to be part of the formula for a 301 Chevy back when the only flavors were 265 and 283. -Brad
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