Main bearing spacers

Who here has ever used bearing spacers in a rb block? I have a tall deck mega block and a kryptonite b crank. Any real world experience with this? This would be a nitrous combo over 1000hp

Yikes !!

Direct Connection used to sell them back in the day for small blocks, don't recall if they offered them for anything else. No issues if everything is to spec.
But not sure if I would use them in your app.

Ive got a set for a small block but still skiddish if id ever use them.

As posted im not sure id go there in your high hp application.

If they are made of steel and pined what would be the problem? Turning? If the crank touches the bearing it's gone anyway. Many was done in 400 Chevy blocks to use the 350 crank, never heard of any problems. To bad someone doesn't make a thicker bearing to do this. To bad Chrysler couldn't make one size for bb and one for sb.

My thoughts exactly, I’ve seen this done in some high hp chevys, so I don’t see why it won’t work for a Chrysler, I’ve just never heard of anyone doing it, other than in a small block mopar

The best guess I can come up with is after 50? years of the BB mopar, if it was "ok" why are they not made and used already?

But hey, they may work if you can get a set made up.

http://www.yellowbullet.com/forum/showthread.php?t=347954

This is the only info I could come up with on the subject, I certainly wouldn’t want to try it, if it’s something that hasn’t been done very much, and it doesn’t appear to be very common at all. I’m a small block guy that’s just acquired a few decent big block parts, so my knowledge with them is very limited

Like cudaman1969 said, used to see it done a lot with the 377" sbc combos (350 crank in a 400)...never really heard of any issues w/ them.

Are you willing to crash and possibly hurt yourself and your car if it fails?
A old friend and racer wreck his 1955 Thunderbird badly (He was lucky and only got bruise up badly and sore from the harness for several weeks) with a BB Chevy in C gas years ago when he had a cam gear rubbing against the block when he installed a roller cam with no thrust bearing, it was making metal and I had warned him to take the motor apart to identify and fix the problem, he didn't before he wreck it It spun a rod bearing and broke the rod in the timing lights at LACR at 130+ MPH, that locked the motor up and made him swerve in front of the other car and go off the track into the embankment flipping the car multiple times
Don't take a chance, sell the B crank and buy the correct one now

FWIW Jesse, I wouldn't want to try it. Get an RB crank.

Cab, to answer your question about wanting to wreck, the answer is no, I suffered that fate last year, I went through the quarter mile traps at 150 to discover I had no brakes. The parachute saved me from serious injury but my truck didn’t fare so well. I ask questions about stuff I don’t know or what I’ve never heard of, then I’ll decide for myself. It doesn’t sound like something I would want to try; again just an asked question.

Thank you chip

I've done more than 25 Chevys with bearing spacers. It's no big deal. It won't cause a failure. If the main line is straight and your clearances are correct the engine won't know they are in there.

There being smart and then just going off the deep end. No way will bearing spacers cause a failure.

IIRC, the bearing spacers for the SBC cranks were an over-the-counter part after years of racers like Bill Jenkins stacking their own to get the same result. No reason why it shouldn't work in my mind for a BBM; it's simply not something that anyone ever bothered to produce for the public.

I agree with the Madman here...no biggie. yes, it isnt the normal " available shelf part". Spacers can be made, and are, all the time for diesel repairs, BBC , BBF and others.If you make a sleeve, the bores are round, the proper crush is set, its no different than the block itself.Some guys use motor bearing sleeves to build up to an available beatring size. So, would I be afraid? absolutely not. ( as I always post, " if done correctly") Is it cost effective or inhibitive in your case, only you can answer that. hard to say

No, it was never produced because why would anyone put a 383 crank in a 440? Plenty the other way around though. I might be wrong but aren't the SS Hemi guys using smaller journals in their engines? I heard Honda bearings.

And I didn't count all the Hemis that came in (and quite as few BBC's) that I had to oversize one or two mains and make up a sleeve or spacer to fix main bores that were ate up.

I guess I should have included on my first post don't try to do it yourself, unless your a competent machinest(SP?)
I know several excellent parts fabricators with very good (expensive 5 axis CNC machines) equipment and skill that could make that part but I wouldn't do that as it would probably be cheaper and safer to buy a brand new excellent crankshaft instead of trying pay for and help engineer a one time set of adapter bearing spacers to save money
I know my limits and skills, I have learned to not try to do things I'm not good at in many things, especially when flying as pilot in command and racing any cars I'm driving

You ever do them ,slice them,and use the cap grinder?

I wouldn't worry about if it would work. But why bother? By the time you get them made/machined, you could just buy the right crank and be done with it.

If I remember right MP use to sell them about
25 years ago.. I knew 1 guy the used them.. it
worked out fine for his street engine.. this
was on a SB.. but I havent heard of them in
a LONG time

I appreciate all the responses about this. Fact is, I wanted to know if it’s been done, simple question. Will I do it, probably not at this point, just wanted some input on the subject.

Back in the day, the original bearing was the spacer.

If they were available I'd probably buy a set. I have access to a billet center weighted 400 mained 4.300 crank.

Me thinks your talking about the beginning of times in American made cars

Bill Jenkins 1973

I thought you where talking about the full floating rod bearings back a long time ago that I have heard of, never seen one myself either

Flat head ford stuff.

I only used them in the smallblock Chevy in my offshore boat ,,but that was years ago...Never had a problem..even at high RPM WOT for over an hour at a time..( in flat water) ..or jammin from full throttle no throttle and right back on to WOT ..in big water..

Why stop at that size, go smaller, after all, smaller journals make more HP. It's not some voodoo thing.

Size matters, especially when it comes to twisting and reversing metal repeatedly

You mean like Johnsons rubber cranks Line was complaining about?
Speek get of cranks, go to the general forums and look at the Cummins engine dyno explosion. Had a good one in it, for awhile!