1971 383, is it B or RB? 440 mount the same? Confused...

[chapel40]

1971 383, is it B or RB? 440 mount the same? Confused...
I bought a 1971 Charger with factory 383. Want cubic inches and trying out how to either stroke it or go to a 440. Would like the hemi but don't have the funds for that. Can someone explain what a B and RB is and what I need to either stroke the 383 or go with something else?

Thanks in advance

[Nacho-RT74]

B blocks are low deck big blocks

RB are higher deck big blocks ( Raised B )

Both are commonly grouped and named Big Blocks ( BB ) while Small Blocks ( SB ) are the A blocks and LA blocks ( Lightweight A )

Engine mounts are the same between both big blocks except the Hemi what also changes the crossmember against the rest of BB cars.

Engine mounts and crossmember changes since 73 ( spool mount kind ), but once again, they are the same betwen B and RB. No Hemi mounts or Crossmember available for these years ( stock at least ) since the Hemi was long gone by 72.

SB got same engine mounts within all the block family too ( once again considering same year change ) but 360 which got one side different ( can't recall which side )

About your engine setup... MY OPINIONS.... stroke it or go with 440 is a matter of prefferences. If is the original matching block ( so then an original big block car ) could be interesting stroke it and keep the stock/factory engine bay parts thinking on a nice restore car job. Stroke it can be a bit expensive than a regular rebuilt and "spice up" job on your 383. But maybe close to same cost than buy the 440 and spice it up on stock stroke. However on a 440 you can also stroke it and will get more cubic inches.

Stroke it requires the larger stroke crankshaft and the pistons for it. You can get a stock 440 crankshaft and rework it ( cut the mains from the RB size to the B size, cut the counterweights to 7.5 diameter and rebalance it ), or get an aftermarket crankshaft already made for that. Get the stock 440 crakshaft limits to the 3.75" stroke UNLESS you modify also the rod journals cutting offset and get non stock rods. There is a larger stroke posiblilities on the aftermarket market ( go 440source.com as an example here http://www.440source.com/strokerkits.htm ). Also there is a harder steel pieces on the aftermarket pieces, but the stock forged RB crankshaft is hard enough for a street/strip car ( wasn't enough with the HEMI too ? LOL )

You can get several rods lenghts for the stroke, either keep stock rod lengths ( B or RB ) or get diff aftermarket options on this too. Pistons must be set accordingly too whetever pices you choose to go for.


Myself, due funds and parts availability ( not being in USA ), went for stroke on stock 440 forged crank what got in hands by casuality, reworked it and installed on my matching numbers 400 with the car ( which is the same than a 383 but larger bore ). Just got the right pistons for it ( Keith Black ) and rest of parts were stock pieces ( but newer performance camshaft and some other miscelaneous parts ). My stroke job was a "cheap" one. At the end I simply got a 440 engine but larger bore built and hidden on my matching numbers 400 block with the car ( so a RB stroke into a B deck height ) even with the stock factory 400 look, which is what I wanted. As a told you, matter of prefferences. Could I get more juice from it? Yes, but didn't need more ( neither had more money for that LOL ), I built it just for fun on the "cheap" and being different from the rest locally, not for race


And welcome.

I'm not an expert, so wait for more opinions.

There is a discussion area here where lot of ppl post their engine experiences and post the dyno charts.

[Bronzedodge]

Low deck big blocks - 350, 361, 383, 400
Raised deck big blocks - 413, 426 wedge, 440

There was a raised deck or RB 383, it was produced 1958-1960.  Seldom seen.

[Nacho-RT74]

426 Hemi is also a RB with of course way diff engine configuration, but same RB deck height and stroke lenghts. Same crank too, but 8 bolts on rear intead 6 of the rest of the blocks

[71charger_fan]

Here's a good write up on the low deck big blocks (other than having an unrelated photo of a '55 engine in it): http://www.allpar.com/mopar/b-engines.html

[chapel40]

Thanks for the replies, guess I have a B low deck wedge block with 4.25 bore.  Not a lot of stroker options for that one huh. 431ci 30 over scat rotating assy is what I found PN  1-48082BI

[XH29N0G]

For the 383, Muscle motors has 3.9 stroke and 4.25 stroke
440 sourse has 3.75 and 4.25 stroke kits.  There probably are others.

[chapel40]

Thanks!!

[alfaitalia]

For the 383, Muscle motors has 3.9 stroke and 4.25 stroke
440 sourse has 3.75 and 4.25 stroke kits.  There probably are others.

Be quick though....they are closing down.  http://board.moparts.org/ubbthreads/ubbthreads.php/topics/2302642/muscle-motors.html

[chapel40]

Im about to rebuild my 383 and trying to decide what to do. Like the Idea of getting almost 500ci out of the 383. Has anyone done the 500 ci stroker? Any overheating problems? Will be a street car. Want to keep the cyl. at .030 so it will have some life if something goes wrong or I live long enough to need to rebuild it again.

[cdr]

Im about to rebuild my 383 and trying to decide what to do. Like the Idea of getting almost 500ci out of the 383. Has anyone done the 500 ci stroker? Any overheating problems? Will be a street car. Want to keep the cyl. at .030 so it will have some life if something goes wrong or I live long enough to need to rebuild it again.

Drive my 512 all over & has ac, runs nice & cool down here in Southeast Texas, built out of a 400 low deck, you should have similar results with a 383 block.

[chapel40]

Thanks