Thread: Cubic Inches

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someone told me once that for all small block chevys it is the same block just different rods and other various things but i was not sure is this was true. i mean what makes a 327 differ from a 350 i mean the 327 has longer rods right that what makes less c.u. and the 350 has shorter rods.

and what does it mean to have and engine bored and stroked i know what it means to bored and engine but what does it mean to stroke one.

and that brings me to my last question what is a 383 stroker engine what does it mean to be a stroker.

SBC Bore and Rod Specs

Pretty sure a 383 is a 350 bored .030 over with a 3.75 stroke(r).

Strokers have longer con rods which equals longer strokes. 305's and 350's are same block I know but that's about it... Not sure, good question!

The con rod length alone will not necessarily change the stroke depending on the pin location in the pistons. Stroking means to use a crankshaft which has a longer throw. The SBC 350 has a throw of 3.48" while the SBC 400 has a 3.75" throw. In the past 400 cranks were adapted to 350 blocks but today there are a number of places to just buy a 3.75" throw crankshaft new. After the throw is changed care must be taken to match up the new crank with the proper rod length and pin location in the pistons to keep the piston near the deck height of the block at top dead center. Stroking the engine increases the swept volume of the engine displacement and usually improves the low end torque but may reduce the top rpm. I don't know much about 327s but I think the stroke was 3.25" so the 327s tended to rev higher while the 400s have a lot more grunt but a lower rpm limit. An interesting additional factor is that if the pin hole is raised and longer rods are used the tendency to detonation (ping) is reduced but often the same 5.7" length rods are used with a 3.75" stroke; this leads to a slight bit more of side slap of the pistons in the bore and also does not help reduce detonation, so 6.0" rods are better with a 3.75" stroke if you can buy the longer rods. I am a novice with the SBC having only helped build my own 350 but I recall when the Ford flathead V8 had a standard stroke of 3.75" and had good low end torque which became montrous when a 4" stroke crank from a '49-53" Mercury was swapped in, so I have great respect for the effect of stroking. In the case of a SBC 350 swapping in a 3.75" crank requires some clearencing at the bottom of the cylinder bores to clear the longer crank throw. I could not afford to pay for this and did not want to chance grinding the block myself so I just settled for a 0.030 overbore rebuild for a 355.

Don Shillady
Retired Scientist/teen rodder

To make it simple:

The difference between a 350 and a 327 is the bore and stroke. A 327 has a small bore and a short stroke.

To stroke an engine is taking the 3.48" stroke of a 350 and making it 3.75 with longer stroked crank... You can also DESTROKE...A common destroke is 350 crank is a 400 block. This makes 377.

There are some interesting facts about different engines. The 292 I6 has a ton of grunt because it has a 4" stroke. When bored out, it has a bore of a 305 (roughly) and the stroke of a 454...TORQUE!!!

"The difference between a 350 and a 327 is the bore and stroke. A 327 has a small bore and a short stroke."

Not quite right. The 350 and the 327 both have a 4.000" bore. The 350 stroke is 3.480" while the 327 is 3.250".

" Strokers have longer con rods which equals longer strokes. 305's and 350's are same block I know but that's about it."

Not quite right. Strokers don't necessarily have longer rods, although most builders will opt for a longer rod to improve the rod length-to-stroke ratio. 305 and 350 blocks are pretty much the same externally, but the 305 uses a 3.736" bore, while the 350 uses a 4.000" bore.

Good explanation Don.

thanks for the correction tech. I would rather be corrected than wrong. Thumbs up!

but if you get longer rods dosent that decrease c.u.

and just for my own vehicle i was told i have a 350 but i have 327 rods in it plus it it bored .60 over so what do i have for c.u. and it my engine still a bored out 350 or do i have to say bored out 327 because of the rods.

The rods make no difference to the stroke. Rod length determines how far up the bore the piston goes at TDC, and thus affects the compression ratio, but the stroke and displacement remain the same.

ooooohhhhh thank you

Originally posted by Nineftfreak
and just for my own vehicle i was told i have a 350 but i have 327 rods in it plus it it bored .60 over so what do i have for c.u. and it my engine still a bored out 350 or do i have to say bored out 327 because of the rods.

Nineftfreak - here's the deal on displacement:

A standard 327 and 350 both have 5.7" rods. So you must mean you have a 327 crank.

Lets assume you have standard 327 crank and rods (5.7"), pistons (.060 over) and a 350 block bored .060 over:

A 350 has a 4" bore.
.060 over (not .60 as thats greater than 1/2 inch) is a 4.060 bore.
Assuming a 327 crank and stock rods and cylinders, your stroke is 3.25".

So the volume of one cylinder is its area*stroke.
Bore = 4.06 (350 bored .060 over)
Stroke = 3.25 (typical 327 stroke)
pi=~3.14 ( a constant value, the ratio of a circle's area as compared to its radius (1/2 diameter or bore) squared)

Area = pi*r*r, where r is 1/2 of the bore (diameter).
Area (of one cylinder) = 3.14*2.03*2.03 = 12.94 (rounded to 2 decimals)
Volume of one cylinder = Area*stroke
Volume of one cylinder = 12.94*3.25 = 42.05 cubic inches (rounded to 2 decimals)
Total volume = Volume of one cylinder * number of cylinders
Total volume = 42.05*8 = 336.4 cubic inches.

Assuming this what you actually have, someone more knowledgeable that I will have to comment on this particular combination's potential.

my bad on the .60 i always forget that its .060 and i was just told that i have 327 rods so the 350 and the 327 rods are the same then that person is wrong and i found out i do have a 327 crank, so that means i have a bored out 327 not a 350, well that suck but oh well this engine is supposed to have 400 hp and i guess that all that matters right.

The last two letters in the number on the tab on the front of the block facing up on the passenger side will help id the block.

SBC Block ID

327 bored .060 over is still 336 CI.

302,327, and 350 all have a 4" bore a 400 has a 4.125 bore
302 has a 3" stroke
327 has a 3.25 stroke
350 has a 3.48 stroke
400 has a 3.75 stroke

302,327 and 350 all have 5.7" rods a 400 has a 5.5 rod

a 383 is a 350 block bored .030 with a 400 crank you can use a 5.5 or a 5.7 rod depends on which piston you use

the bore is the size of the piston, the stoke is how far the piston goes up and down in the bore.

hope this helps