Big Block or Small Block: For That is the Question?

[Kevin Shasteen]

No Guys; not for me/sorry to get your hopes up as I'm still an Inliner.

 

My question tho & this is merely for fun is this: With all the hotrodding of every Amercian Push Rod V8 since its inception, all the parts swapping & all the stroking of each & every engine Detroit ever put out.., what constitutes a Big Block from a Small Block?

 

I have my own ideas but wanted to lure all the thinkers in here to giving their opinions; doesnt matter how simple or complex..I'ld like to hear you thoughts!

 

Kevin,

(Yea,Still an Inliner)

[Michael]

As a big block Datsun adherent, here’s my brain dump on the issue....

 

Each of the “big three” Detroit manufacturers had basically two series of V8 engines – the small and the big blocks (specifically referring to pushrod V8s). Around 1954, the pushrod V8s started coming out (the first was from Cadillac (?) ), displacing around 300 cubic inches, and replacing their flathead precessors. Some 5 years later, new families of larger, beefier V8s came out; Ford had the FE series, Chevy had the W-motors (348 and 409). Ford kept changing their big block species, while Chevy settled on one block design around 1963, with a much-improved combustion chamber and head design over that of the W-series. That became their canonical big block, which was installed in passenger cars until 1976, and soldiers on even today, albeit only in 3/4 ton and larger trucks.

The distinction between BBC and SBC is a little weird, since often the largest small block displaces more than the smallest big block. From what I heard from “serious” hot rodders, the attraction of the big block, besides bragging rights, is considerably higher mechanical strength, better flowing cylinder heads, and greater potential for increasing displacement beyond stock. Typically, OEMs introduced their big block family only after the comparable small block was around for some time; so, the BBC design is often incrementally better. An example (Chevy) is the small block’s close-together middle exhaust ports, which evidently cause local overheating and blown head gaskets, vs. the big block’s evenly spaced exhaust ports.

Hot-rods equipped with big block conversions have a reputation for being unruly race-only machines, too extravagant for the street. This is unfair, as a stock big block can actually be smoother and more drivable than a small block. But, once you go BBC, the temptation to modify way beyond stock is just too great. After all that work just to make it fit, why keep it stock?

Unfortunately, the OEM big block is rapidly dying. Small blocks will soldier on in one form or another, even if GM does terminate the Camaro/Firebird line, and Chrysler never builds a [non-exotic] rear wheel drive car again. Undoubtedly they have the strength in numbers.

 

About big blocks and Datsuns…. Well, as I see it,

 

basic hot-rod V8 Datsun = SBC;

all-out race car V8 Datsun = BBC.

 

An entry level small block is MUCH cheaper to build than an analogous big block, which is where I choked in my own project. But, as the power level climbs, the costs begin to even out. At around 600 hp, I’d say that the big block is actually cheaper – and will have a smoother, flatter torque curve as well.

[Guest Anonymous]

Also:

 

SBC parts = $$

 

BBC parts = $$$$

 

 

Lone

[Mikelly]

....And another thing to mention is powerband... You don't need to twist a small block like you would need an inline 6 to get great torque and HP Numbers. Just like that comparison, You don't have to spin a big block as high as a small block to get the same, if not more power.

 

However, in a Datsun, where weight placement can be an issue, I wouldn't recommend building a big block unless you enlist the services of Michael and use his big block as an example. The man has a 50/50 weight distribution in that beast, truly a work of art... And the only way to go big block if you are doing more than quarter mile sprints!!

 

Mike Kelly

[Guest Fast Frog]

Michael;

 

I'm impressed with your BBC/SBC comparison! One of the many better posts I've read on this forum!! And Mikelly, your additional input is deserving as well!

 

Thanx much!!

 

Rick

[RPMS]

The way I see it, there are three main reasons not to go with a big block if you're either going to track race or street your Z...

 

1) Weight. The weight of a small block can be compensated for. Unless you're going to cut into the firewall to move a big block even further back towards the centerline of the car, you're going to be front heavy. If you don't choose to cut into your firewall, you'll adversely affect handling.

 

2) Expense. One look in the Jeg's catalog should tell you that, as LHDR says, BB parts ain't cheap.

 

3) Traction problems. Since traction is the limiting factor in most SBC Z conversions I've seen, I don't think plugging a BBC in there will help matters any, unless you're going to put in wheel tubs and drag slicks. in order to put all that torque to the pavement. With tubs and slicks, driving it on the street is somewhat silly, IHMO.

 

Of course, if you're going DRAG racing, then all bets are off. Buy the big block, install tubs and drag slicks, and embarass a few Camaro-driving rednecks at the strip!

 

I guess my position can be summed up thusly... Having a big block is like having a 15" wanker. It's fun to brag about, but when the rubber meets the road, what are you going to do with it???

[Guest Anonymous]

Pass out due to blood loss..

 

Regards,

 

Lone

[DavyZ]

If I was building a Chevelle or just about any "large" American car, I can have a relatively mild BBC and make it haul beans. I'd have to pump a SBC to get the same kind of performance in the large ride (IMO).

 

To a small car like a Datsun, the SBC is a HUGE engine in comparison to the I6!!!! It is a "big" block to the Datsun. Get it?

 

For my Z--SBC all the way, Baby!

 

David

[Guest Anonymous]

Yeah, I think I'd agree with Davy, the sbc will provide all the addrenelin a average speed junky will need. For the hardcore engine swapper and speed junky with a major fix, the big block is an option. The SBC will give you the visceral excitement you'll probably need though.

 

Regards,

 

Lone

 

Kevin, your in Texas right? You should hook up with the posse down there with the V8's and get a ride from em...

[Kevin Shasteen]

Thanks for the responses everyone; but for clearification purposes only-I'm not considereing a BBC for my Z. I intended for this thread to be something that determines or differentiates a BBC from a SBC.

 

The reason I posed the question is the result of my reading on perf.engines of Mopar, Ford & GM; wherein, each displacement of their V8's have ben honed, bored, stroked/blown & turbo'd to the max as we now have small blocks surpassing the displacements of the typical big blocks...so my question was more of a phylosophical question which usually leads to factual/reality type answers.

 

Since there are small blocks stroked to the hilt utilizing con.rods from big blocks which yield amazing torque.....at what point does a small block become a big block/or is the differential between the two merely one of outward dimensions? I liked Mike's trip down the history lane & found it insightful.

 

What I found interesting is that the crank journals are not that much larger nor are the connecting rod journal thickness of the crank that much different when going from a small block crank to a big block. The stroke/rod length ratio is however quite a leap when looking at stock small blocks & stock big blocks; as are the valves to port ratios & the valve to piston deck area ratio's.

 

My quesiton was hopefully posed from the angle of this: If we were able to shrink ourselves & enter the inside of a small block & walk around (no, I'm not on mind altering drugs!)...what would we find different from a big block if we did the same?

 

Just attempting to get all of us thinking; I like challenging questions; So again, what differentiates a Big Block from a Small Block-is it merely the engines ability to breath complimented w/a longer stroke & larger connecting rods because if that is the only thing we are going on, then there are a lot of stroked small blocks which could be considered big blocks(?).

 

Kevin,

(Yea,Still an Inliner)

[Guest Anonymous]

Physical size of the block is what makes one a big block over the other. You can poke and stroke a small block chevy as large as you want and its still going to be considered a small block chevy because thats what it is, its based on the 'small' block. Its not a term used to describe cubic inches, Chevy had the 396, 402 and yet they made a small block that was 400 inches (which wasn't considered a performance engine at all, even the 350 was shunned by many a rodder way back when the 327 was the 'happening' engine) why they did this I don't know.

 

Same with the Mopars, put a 383/440 next to a 273/318/340 and you'll see what the terms mean.

 

As boring and uncomplicated as it is, I think that is the meaning of the terms IMHO.

 

Regards,

 

Lone

[Kevin Shasteen]

Yea Lone, I tend to agree w/you; it all boils down to the outer dimension/measurements (size) of the L x W x H of an engine; still its an interesting concept to ponder(?).

 

Kevin,

(Yea,Still an Inliner)

[Michael]

Also, the big blocks and small blocks are two completely different families of castings. For example, in the Chevy line, the SBC as 4.4" cylinder bore spacing (centerline to centerline), while the BBC is 4.9" (I may have the exact numbers incorrect, but they're close). This is why there can not be a 4.5" bore small block - you just run out of block! There may, however, be aftermarket redesigns that allow nonstandard overbores. Companies like Merlin make "superblocks" - loosely based on the stock big block - that allow 700+ cubic inches. That's "two" 350's!

 

Parts from one family do not interchange with those of the other. The ONLY exception is the distributer. If you somehow use rods from a BBC in a SBC, you will at the very least have to do something about the main journal diameter, which is much larger for the BBC.

 

I do agree that for most Datsun conversions, big blocks are overkill. In my case, the fellow that did the welding was a BBC lover, and convinced me to follow that route. Otherwise, I would have bought a 383.

 

Mike Kelly - thanks for your compliments! - but the metalwork of my car was done by a hired gun - I would not have been able to get this project done alone. It's one thing to design, and quite another to actually build.... Now I'm learning that I can't even tune that engine properly. Ah, theory vs. practice.

[pparaska]

I think it was said above somewhere but I think the answer is simple:

 

Manufacturer A develops a V8 in the 50s. It's known as their V8. Then manufacturer A decides it needs a bigger engine (with the casting technology (minimum wall thickness) of the day) and develops their "Big Block" V8. The original smaller engine is then known as a small block.

 

I believe this is what happened at Chevy, Ford, not sure about Mopar. I think others (Buick, Olds, for instance) started with larger blocks and went smaller (or used the Chevy SB in their cars).

 

I think it really comes down to the manufacturers coming up with different sized engines at different times and the names being given to differentiate them. Remember, when the BB Chevy came out, the small block was only 327 cu in. (maybe only 283, not sure when the BBC came out).

 

[ May 30, 2001: Message edited by: pparaska ]

[Guest Anonymous]

I agree Pete. The SBC/BBC monikers came later, I don't think the factory called them that immediately. As far as Ford and Mopar they had engine series numbers and didn't refer to them as small or big block. For Ford it was 'Windsor' which became known as the smallblock, 'FE' (Ford/Edsel) which became known later as they're big block, Ford also used the '385' series of engines which was the 429 Thunderjet and the 460 used in lincolns (still used today in truck and aftermarket performance applications) both of which of course became known as big blocks.

Mopar smaller engines are a tad more messy as far as designations, but essentially you have the 'A' and 'LA' blocks. 'A' block being: 277 - 301 - 303 - 313 - 318 - 326, the 'LA' block being:273, 318 (5.2), 340, 360 (5.9) all known later known as smallblocks. Larger block designation were: 'B' 361, 383, 400 and 'RB' 383, 413, 426 Wedge (not Hemi), 440 which became known as big blocks. Also you had the Hemi which is a murky line of designations that spans a huge variety of engine sizes some way below 300", most consider the 331-392 big blocks none the less and the 426 later. Mopar's engine line was so varied, I didn't even touch on things like the Red Ram engines or the Poly headed engines (essentially a Hemi type block but without Hemi combustion chambers).

 

Whew... Clear as mud huh? My point being I think the Small block/Big block monikers were later used by enthusiast to distinguish a certain line of engines and was probably not used at the factory to designate an engine family.. (took me long enough to get to the point huh, but then again it usually does..)

 

Regards,

 

Lone

[Guest John Adkins]

Mopar V8 engine families aren't really that complicated if you think of it this way:

• The first mopar V8 was the early hemi ("red ram" "firepower" "whale motor")

• A("Poly")/LA-engine -- hemi heads were too expensive- so poly heads were introduced on on hemi block. The LA- ("Late A" or "small block")was an updated "A" engine with wedge heads, lighter block casting, other upgrades

• B engines ("Big Blocks") another engine design with wedge heads.. RB is the B engine with a raised deck(440). Late Hemi is based on B/RB design but with new hemi heads

with Chevys arent the families like this?

• small block --the LT1,ZR1, LS1 are based on the small block...

• w-motor big block (348 - 409)
• Mark IV present day big block (396,454, etc)

 

[ May 30, 2001: Message edited by: John Adkins ]

[pparaska]

lenster, yeah, you can tell by looking.

 

Me too. If I was building a bad 69 Camaro, It'd have a BB in it . Always liked that body style. If it was a 70 Cuda, it'd be an RB or Hemi - probably just settle on the 440 . Of course, I've got a special place in my heart for 427 Cobras and 428 SCJ GT500 Shelby Mustangs - had a ride in the former lately, and had buds with the latter in High School! Fun stuff. I'm an equal opportunity car guy.

 

Chevy calls there BBs Mark IV. Then the smallblocks are now called Gen I, Gen II, Gen III. Those are pretty much determined by when they were built, unless you have an early racing Gen III, I think.

[Guest Anonymous]

Thanks for the help on the Mopar line John, it did sound more complicated than it is really.

 

I've always liked the RB engines, nice to work on and are pretty strong runners, put in a cuda this is fun as all get out (you have to love the Hemi Cuda though).

 

For Ford stuff, I would these days go with the 460, its stout and a great performer (Love to have a Kaase built 460 in a tubbed 57 Ford 2dr).

 

For Chevy, wow, so many good ones, but would probably go with the 427 or the 502 crates (easier to get and plenty of power). Either of those motor in a early Camaro will give you all the excitement you can handle this side of a all out drag racer.

 

Maybe someday a BB in a project car, but not in the Z, to much work and to much weight IMHO.

 

Regards,

 

Lone

[fl327]

i always thought that you could just tell them apart by looking at them, a rat is just physically so BIG!!!! not necessary to be real fast in a z and retain some cornering though.. unless its 502 ram jet with nitrous in a 1990-96 300zx!!!!! if i were building an big domestic ie. ss nova, ss impala, vette, maro, chevy etc etc., i would go the biggity biggest block i could, but that is not the case with my aluminum can with a v8....

[Cable]

Bump.....