For the most part it does. Thanks.tv_larsen said:Basically, the difference is deck height. The RB's have a taller block to accomadate a longer stroke. Because of this, the intake is wider, and the distributor and push rods are longer. They also have larger main bearings.
383's and 400's are examples of B blocks, and 440's are RB blocks. Does that help?
Yes TV, he's correct. There was an RB 383 in the early years of RB production. It's as rare as a free 426 Hemi, or a 350ci B engine, but it was available nonetheless.............Lostv_larsen said:Are you sure? I've never heard of such an animal. Actually, that sounds like the bore and stroke of a Chevy 350 stroked to 383 cubes.
While a 68 GTX and 68 Roadrunner both had "906" heads, the 383 is still a B block and the 440 is a RB block.aepowell said:I believe all 383 road runner engines were rbs. They had 440 heads ,intakes and exhaust manifolds on them. Please correct me if I'm wrong.
Jay, would'nt the additional mass of the RB pistons actually rob that energy from the drivetrain rather than contribute to it?Cbody said:That doesn't really answer my question, but I'll go ahead and throw this out for discussion.
I hear the "faster reving" argument quite a bit in reference to the 383 vs. 440, and 451 vs. 440. For all intents and purposes lets assume that the lighter reciprocating assembly has a similar effect of a lighter weight flywheel.........now in a stripped A body I can very well see that it's a desireable trait, especially in race conditions, however, in a heavy truck I can't hardly see how the lighter mass of internal parts has much bearing on how the truck runs (or more specifically launches), in fact, it can tend to be detrimental as it will take more throttle application to accelerate the truck than if you had the inertia from the additional reciprocating weight helping to get the rest of the drivetrain in motion. End result, it'll take fewer RPM to move the truck from rest with an RB than a B block, or even a low deck stroker. How "fast" an engine revs in a no-load situation is really a moot point, how fast it revs when under load is what counts and in that situation the RB will always outperform a B when similar builds are compared.
Continuing fast and loose... ;-)Cbody said:Playing fast and loose here for a second the short answer is yes, the additional mass will effectively rob HP (using a 451 vs 440), and in a light weight car in a drag race situation it can make a difference. However lets make things more equal by using the same lightweight pistons in a 440 and the actual reciprocating weight difference is considerably less.
I am starting to see your point here but isn't the inertia of the crank maintained by good timing and combustion? That said, a lighter assembly should once again be superior because it would take less energy to keep in motion and quicker to respond to changes as well.Cbody said:That said, the HP required to spin an engine is far less than that required to accelerate a vehicle up to speed.......especially a heavy vehicle. Since the reciprocating assembly is in motion it's also in effect "storing" energy.....albeit not as efficiently as an actual flywheel. The effect of that extra mass rotating helps get the other drivetrain components in motion. Similar to a heavier flywheel, that stored energy is converted to motion once vehicle is accelerated.
A rather poor analogy (but apt) would be to compare a motorcycle engine to an automotive engine........the cycle engine can rev nearly instantaneously, while a stock automotive engine will seem rather sluggish in comparison.........but the cycle engine also drops back down to idle much quicker as well.....because it has little reciprocating mass. What that means in the real world is that it's considerably easier to stall upon launch unless the revs are up (using manual transmissions as comparison), whereas a large engine can nearly idle away since the rotating assembly helps by using it's stored energy initiate movement.
I'm not sure I agree with that but I know you have had both so I will take your word for it....Cbody said:End result.......with a smaller stroke or lighter reciprocating mass engine it'll take more throttle, and more rpm to accelerate. Fine in a race car, but not as good in a heavy vehicle. Seat of the pants feel, and actual acceleration #'s will bear that theory out I believe.