Stupid question but I don't know the answer. Can you say Newbie

[blown74]

Okay can someone please explain what B/RB is all about? 
Thanks Don

[belgiandodgefreak]

could be wrong,

but i believe B is for BIG block
RB is for HEMI

[PlumCraZRT]

Newbie...      B and RB refers to the deck height of the engines.  The deck height is the distance from the center line of the crankshaft to the surface where the heads bolt on.  On "B" engines (or Big-block engines), the deck height is 9.98".  On the more sought after RB engines (or Raised Block engines), the deck height is 10.725".  Chrysler basically designed the RB engines to increase the rod-to-stroke ratio and to give the pistons an (incredibly huge) compression height.  Both a high rod-to-stroke ratio and compression height will (theoretically) give better reliability.  See... those Chrysler engineers were lookin out for us!!  Easiest way to remember all this is that 361-383-400 engines all share the B-block and the 440-hemi share the RB block... I know I'm leaving out the old 392 hemi etc... admittedly, I don't know where the more vintage engines fit in.  I think they were B-block but perhaps with a unique casting to them.  Anyway, the B blocks look dimensionally smaller on the outside (and are dimensionally smaller on the inside) to the RB blocks.  On a more personal note, and perhaps why im making a 400-451 stroker, I prefer the B blocks not only because they are easier to work on, but because performance-wise they don't give up much to RB blocks and because they are lighter.  Some drawbacks to B blocks is the lack of cross bolted mains and more "super"-high-performance that the RB block featured.  On the otherhand, a similar displacing engine in the B block format will spin better (and hopefully create more power) due to the decreased weight in both the lengthy rods and thick pistons.  The hemi/RB engine architecture is considered the basis for what are now modern day top-fuel race car engines... something to think about.  Even without these "racy" features, the mopar B engine has plenty to offer in line of performance.  They  were smart enough to make all parts interchangeable between B and RB engines with the exception of intake manifolds, distributors, and hemi heads (as far as I know), which lends credibility to their performance potentials not being too different given similar displacements and components.

[belgiandodgefreak]

 


thanks for the correction, this is something why i became part of this forum, always learning cool thing.


i'll be quiet now 

[HP2]

You forgot a few displacements: 350 was the first B displacement, 413 and 426 wedge are RB.

Only the Hemi is cross bolted in the mains.

On the smaller side of things, A engines were polyspherical headed engines made during the 50s and early 60s. 50s era A engines will accept early model Hemi heads. After around '59-'60, the bolt patern changed and it was no longer possible.  LA engines are "Lightweight A" castings. Began with the 273 in 67, the 318, 340, 360 and eventually morphed into the Magnum engines that were used up to a few years ago.

[blown74]

Thanks for the great info !! Could or would a 440 ever be cross bolted in the mains? Is cross bolting like spaying a 2 bolt chevy block and making it a 4 bolt main?

[Chryco Psycho]

you can modify old 440 blocks or buy new castings crossbolted
 the splayed caps on a GM are totally different , the Hemi has the extra bolt come through the side of the block from the outside @ 90* to the cap bolts in the oil pan