hi
i've always wondered what the true meaning of the big block and small block were. what are the actuall differences in them, and how do you determine if they are or not, other then just know from books ect.
thanks for any information
and remember

 

Big blocks include, but are not limited to
all FE's, even though some are smaller than the
larger small blocks, and the 370/429/460. There
are also MEL family of engines that are considered
big blocks also...
Small blocks come in the following sizes...
221/255/260/289/302/351W,C,M/and 400.
Mod motors are 4.6/5.4/6.8 L sizes...
There is also the Y-block family of engines,
256/272/292/312, and the Lincoln Y-block but
I don't remember the sizes...

Steve & the Rockette
'63 F100
'68 F100
'72 Capri 2L
'73 Capri 2.6L V6
'73 MG B GT 2.6L V6(Ford)
'98 Contour SVT 2.5L V6 (Mods)
'01 ZX2 (No Mods yet)

 

I think he's looking for " What is the criteria to determine if a engine is a small block or Big Block".

The Ford 400 cu " engine is a small block
The Ford 390 FE is a Big Block
But a GM 396 Cu" is a Big block
A Mopar 383 is a Big Block

Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"


78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon

 

Funny thing is that all the high-perf catalogs I've seen so far doesn't group the 351C/M and 400 as the small blocks. 400 is kinda odd as it has larger displacement than some of the "big blocks" and also have same bell housing pattern as the big blocks and also uses same disturbuter as the big blocks, but has the same bore size as the small blocks. So I'm not quite sure where the 400 falls under, but in the Chubby Land, they consider the 400 to be a small block.

 

That's kind of how I have viewed the difference was in the change in bell housing bolt patterns...that would make the 351W and 351C small blocks and the 351M and 400M big blocks....but they are really neither...

 

I believe the spacing of the bores of the block would be a big deciding factor whether to catagorize it as a big block or small block. Since the 351c/351m/400 have the same spacing as the 302/351w, then they are grouped with those engines("small block"). I can't seem to find the exact dimensions in any of my books, but the big blocks certainly must have a wider spacing between the bores because alot of them have pistons that are bigger than 4 inches.

 

Bore spacing for the FE's + 4.630"
Bore spacing for the 335's and Windsors + 4.380"
and, for the 385 series, 4.900"

Steve & the Rockette
'63 F100
'68 F100
'72 Capri 2L
'73 Capri 2.6L V6
'73 MG B GT 2.6L V6(Ford)
'98 Contour SVT 2.5L V6 (Mods)
'01 ZX2 (No Mods yet)

 

Here's another topic to branch off on. Do you guys prefer small blocks or big blocks in your trucks? I kinda like small blocks because they spool up faster, but you can't beat the torque of a 460 stroked out to 509 with a blower and twin carbs up on top.

-Jon

 

hi
thanks for the information. but it still seems to be a mystery! maybe be with all of our minds together, we can figure it out. it really seem to be in the dimensions. I prefere certin engines for certin applications. small block for racing with lighter cars and big block where towing and long range abuse is nececary. At work we pull fifth wheel trailers alot. one truck is a 199? somthing crew cab 460 and the other is a 78 bronco and a 400M. Beleave it or not the bronco with the same weight can out accerlerate the crew cab. And the crew cab is a 5 speed, low geared f350!

 

General rule of thumb. If an engine series was available over 400 cubic inches it was considered a big block. eg 396/454 chev= big block
265/400 chev=small block. FEs were available over 400 cubes=big block,335series up to 400= small block Bountyhunter

 

Beleave it or not the
>bronco with the same weight can out accerlerate the crew
>cab. And the crew cab is a 5 speed, low geared f350!


Something you must remember is that you are dealing with a lot heavier truck in the F-350. Whether it's a 460 with a 5 speed or not. It out weighs the Bronco. I have a 65 F-100 with a big block 390 that can out accelerate a new chevy truck from a rolling start (there's one or two around here, that found out the hard way.) But not off the line, because due to the torque of the motor, it would just melt the hides off of the rear tires.

 

This is probably how Ford would word it in their literature:
"the largest smallblock available in 19XX is the 400 CID 2V."
or
"The smallest big block available for 19XX cars is the 352 CID 2V."

If anyone is familiar with Ford advertising in days gone by.
Mark

 

According to the "How to hot rod ford engines", it refers to the 351C,351M, and 400M as a "Mid block". This is because of the exterior dimensions of the blocks.

 

> According to the "How to hot rod ford engines", it refers
>to the 351C,351M, and 400M as a "Mid block". This is because
>of the exterior dimensions of the blocks.

That's a silly book considering the "C" has a .3" SMALLER deck heighth than the Windsor. The 400 and the M do have a larger deck but bore spacing and bore are the same as the "small block" 302/351.

 

The outside dimensions of the "C" and "M" blocks, are larger than the 302/351. The 302 Boss, which had "cleveland" heads, was considerably smaller than the "cleveland" block (width, not deck height).
I believe they refer to these blocks as "mid-blocks", because the outside dimensions are quite larger than "windsors", not just considering the deck height, but the width of the blocks, which also indicates a different degree of V angle.


>That's a silly book considering the "C" has a .3" SMALLER
>deck heighth than the Windsor. The 400 and the M do have a
>larger deck but bore spacing and bore are the same as the
>"small block" 302/351.