Who has info on weight of big block vs. small blk

There's also a wildcard here. REPLACEMENT small blocks (R3, 340 Resto Blocks, etc.) are considerably heavier castings than original 318/340/360 blocks were. Most original blocks weighed in at around 165lbs with caps, replacement blocks are up around 220 (that's right in there with a vintage 440 or Hemi block!). Modern wedge and Hemi castings also wiegh allot more than vintage blocks.


So, it depends on which engine block you start with, not just which bolt on parts you use.

Out of the moparts tech archives.


Slant Six 475

273-340 "A" V8 525

360 "A" 550

361-383-400 V8 620

413-426W-440 V8 670

Street Hemi 765

lets use a 68 barracuda as the test car for this .
lets say you have a 340 barracuda with all stock parts(cast iron intake, exaust manifold and stock heads) and you put in a 440 with alum heads,alum water pump and wp housing, alum intake and tube headers. do you think that the 440 would weigh what the full dressed 340 was?

it appears that a 440 is 145# heaver than a 340

does anyone have real world # of the wight savings from 440 stuff like
headers vs exaust manifolds
alum heads vs stock 960's
alum intake vs cast iron(these could very depening on intake)
and alum water pump and housing vs stock cast stuff
and light weight start vs stock.


It would be interesting to see how close it comes to a stock 340 cuda weight

I know a factory Iron small block head weighs about 1 pound more than an iron big block 906

I figure aluminum from iron saves 20 pounds per head...a smallblock is more like 22.

BB Water pump housing saves 10 pounds, pump maybe 2. SB's already aluminum!

Intake I think I figure 35 iron 383 vs between 15 and 18 pound for aluminum.

aluminum radiator maybe 10-12

Lighter bobweight rotating assembly can easily save 6-8 pounds

B motor pushrods weigh ~1 oz less than RB....that's a pound right there!

Headers, too many variables, thick flange headers with 16 gauge tubes might be a wash compared to cast iron....cheapie 18 gauge with 1/4" flanges probably save 10 pounds each. Too many variables.

so I figure my installed aluminum low deck 517 with the radiator saves about 90 pounds over the the original 440 that the car came with.....or about the same as a factory 340 would weigh. it'd be a little lighter without the hard block but I'd rather have it in there

I don't think a bare 440 long block with an intake is really 120 pounds heavier than a 340, the block is roughly 60 pounds more but the heads and intake are probalby 10 pounds less (340 4bbls Iron is a comparatively heavy piece) but even adding the crank difference it's hard to find an answer that adds up to the other 60. But maybe it is over 100 with the manifolds.

Also Static weight probably isn't as big a factor as dynamic weight....stepping the aluminum heads not only lowers the mass and decreases the front weight bias...it also lowers the center of gravity. Dynamically taking off 10 pounds with an aluminum radiator hanging 2 feet ahead of the axle is like taking off 20 1 foot ahead

Your answers may vary but you really need to scale it if you want to know for sure. you can get carried a way...Ex: A holley is a few pouunds heavier than an aluminum carter

Thanks guys, I keep forgetting about the bazillion variables It sounds like a big block fitted with aluminum goodies gets it real close to an all cast iron small block(within a few pounds).