lets say your doing a new ENG. it's all paid for...you add a few more parts..and the shop sends you Updated paper work, showing a 421cid. and you orderd a 427 cid. now they tell you no prob, we can just do the 427.. But! THE 421 RUNS BETTER ON THE STREET. with it's 3.875 stroke. and the 427 has a 4.00 stroke.. now i know better.. as more stroke = more Torque but why try to Pull that one off My email to Him Hi Reid looking at the Update.. it should be 427 you have listed 421. could you check that... Thank you Jeff Brown ********************************** His reply to Me in Email Hi Jeff, We can change it to a 427 for you if you like. I put it in there as a 421 because the 3.875" stroke in the 421 is more street friendly than the 4.00" stroke in the 427. The rod to stroke ratio is better. If you would like me to have it built as a 427 though just let me know. Thanks, Reid *************************************************************** now i have not replyed yet, but i could never see anything listed any place that the rod-length-to-stroke ratio (L/R) is better on the street eng (myth) to me. 421cid 6" rod 3.875 stroke= a L/R of 1.55:1 427cid 6" rod 4.00 stroke= a L/R of 1.50:1 so any of you ricky race eng guys.. what do you think?? any PROOF the L/R of 1.55 is better on the street then a L/R 1.50 i have never seen any

427 all the way.

427.

it will be a 427..

they sent me that email back on Jan 18th.. have not emaild them back yet.. no rush.. as i orderd and paid for the 427.

it's nice of them to look out for me. and redo my paper work from a 427 to a 421, with out asking... No biggy..

im easy going..layed back.. paid for this back in Oct 15th.. no rush..
old eng still in the car.

for the same price i could get a 454 small block chevy..
but always wanted to have 427 in and on my Camaro

and the combo with my parts will be over 560 fpt
and after all we know torque is what moves the car.
and at 6000rpm i dont think a .5 diff in the L/R will make a diff.

I bought a 427 because I really wanted a 427. My engine builder really tried hard to steer me towards a 3.875 stroke. The shorter stroke gives more cam clearance and apparently less stress on the caps, rods,crankshaft and block . For the same quality of parts you can spin a shorter stroke to a higher rpm and make more horsepower. One downside is the larger initial bore size limits the amount of material left for a rebuild.
My thoughts are for a street engine that is not going to be built for the absolute highest power possible, more cubes and a longer stroke will make a more street friendly motor for the same horsepower. The shorter stroke is more suited for a race motor built for maximum possible power.
The rod to stroke ratio difference is probably important once you start spinning 7000 or more rpm.

Torque:
when you make 500 + FPT from 1600rpm all the way upto 6000rpm
HP takes a back seat. on the street.
and making close to 560+ Hp. at 6000 your fine

as for the parts this 427 is with a Brand New Dart Block.
Mech roller under .590 lift, so there is lots of room in the bore.
for a make over in a few years. could go to 434 or 454

this is not a all out drag car.(even if it has all the parts of one) so most the RPM it sees will be in the
2000 to 6200 RPM ball park. with most it's life in the 2000 to 4000rpm
on the street, and it's nice when you have 500 FOOT lbs of Torque
to play with even at 2000 RPM. a eng that revs to 7000rpm making power.
will never see 500+ FPT at 2000 RPM.. now you take and add a

9" 3000 stall covrtr. with 4.10 gears. You will need a Big Set of sticky tires. cars like this. can run low 11's in the 1/4 mile. like backing out of the driveway to do it..

iv done the 8000rpm eng's in the past... i like, the long life Big Blocks,
making Gobs of Torque. under 6200rpm

and the chicks dig it when you have a 427 under the Hood.
(and they can drive it)

but your right.. for the street, Ya want Big Cubes long strokes
and Gobs of torque!
after all Hp is Just Torque over time.

Wow! All this drama for 6 little cubic inches... and thats all it comes down to. There would be no real difference in power between the two.

Both suffer from pretty bad rod/stroke ratios, stroke dose not make torque sespite "common sense" it simply makes more displacement.

If you actualy do the math you'll see that the idea that a long stroke inherently makes torque while a short stroke makes power violates several laws of physics.

it's not Drama.. Its Facts.

a 427 with the same parts will make more power then the 421
and make more torque even if it's 6 Hp more..it's more

and the L/R is not bad..
a 383 with a 5.56 rod = a L/R 1.48:1 (stock 400 rod)
use a 5.7 rod it = a L/R 1.52:1
use a 6.0 = a L/R 1.60:1

and the 427 with it's 4" stroke and 6" rod is L/R 1.50:1
and iv never see any Proof anyplace that thats Bad.

the L/R is just under a 383 L/R with a 6" rod
and lots of 383 have 6" rods. and just over a 383 with a 5.7 rod.
and ther have been lots of 383's with 5.7 rods..

ill stick to the 6"rod and 4" bore. and make more power with the 427

Hp is Torque Over time.. we take the time off and just make Torque.. Hp will follow...Math is Fantastic!

take a 550 fpt 575 Hp eng with a 3200lb car
and race a
480 fpt eng with 600hp in a 3200lb car
who do you think will be faster

with all the gears and parts the same
more Hp or More Torque..

my Votes on the Torque
just me

427. 4.125" bore 4.0" stroke = 427/428

100 engines built as 427s may on average make more power than 100 engines built as 421s on average... but 6 cu-in (less than 1.5% difference in displacement) is close enough that an individual 421 could actually make less power than a 427.

The real issue is what your mechanic said, the rod to stroke ratio is better with the 421 so it may make more power with the same combination of parts because there will be less cylinder wall friction. I doubt you can run a 6" rod in a 427 because the longer stroke of the 427 ussually requires a 5.85 rod. The 421 may be able to use a 6" rod so its rod to stroke ratio will be better. The 421 also has the advantage of a larger bore that can allow the heads to flow a little better. All things considered it may mot make much of a difference but you engine builders argument is a valid one. The 427 will have a rod to stroke ratio of 1.46 and the 421 will have a ratio of 1.54.

427 with it's 4.0" stroke and 6" rod is a L/R 1.50:1

the 421 has the shorter 3.875 stroke is a L/R of 1.55:1
same 6" rod.

Close enough to make no measurable difference.

BINGO.. thats what im sayn

this is all going together with a Aftermarket Block.
My old 383 is on a BowTie block. (will see whats wrong with it)
this could be the nexed 440 small block

this new 427 will be on a Dart block (thats what im paying for anyway..lol)

I do not believe you can get a 427 with a 6" rod, that is why I listed the commonly available 5.85 rod for the 427. You can do whatever you want, you asked for our opinion on what you would buy, and I gave you my opinion and the reason why.

If you are using an aftermarket block why not build the other 427? Use a 4.185 bore and a 3.875 stroke and you still end up with a 427 yet you retain all the advantages of the 421 engine layout. Slightly better rod to stroke ratio, better breathing, and you still have 427 CID? Just a thought.

If you really want to build something crazy (but good) use the aftermarket block with the 4.25 bore (I believe it is made by Mowtown, but any of the good aftermarket blocks can work with this bore, you just need to check for core shift) and use a 383 crank offset ground .010 for a 3.76 stroke. This will also give you 427 CID and it has many advantages. (Big bore, best rod to stroke length of any of these combinations, and classic dimensions of the 427 BBC) This is what I am planning to build for my drag week car in the SB NA class.

thanks for your imput.. and info.

i like to Keep my bowtie and dart blocks. low on the Bore, when they are New. so if i ever want to reuse one, and need to bore it, it's there to use.
and can be bored even More.

even at this time i might upgrade to a alum block and drop another 90lbs off the car.. am looking more into that has well..another $1500 bucks!

Absolutely you can:

http://www.summitracing.com/search/P...keyword=piston

As a matter of fact, there's 8 different pistons returned for the 4" stroke/6" rod combination, but only one for a 3.875" stroke/5.85" rod, which says something about the relative commonality of the two combinations.

http://www.summitracing.com/search/P...keyword=piston

On the other hand, that one piston is only $81.95, compared to $113.39 for the cheapest of the others with their ring support button requirements. In the end that's slightly offset by the lower price of a common 6" rod compared to the oddball 5.85".

Depending on the block you might be better off with a 421 versus a 427 because of the sacrifices you might have to make to get the extra cubic inches. Those sacrifices might cost you some power such as in the camshaft. I would listen carefully to the builder.

I would go with 434. Little M block?

A 434 is a 427... same block, same stroke.

thats why you start off with a smaller bore. with a new after market block.
if you ever have to rebore. you have the wall to do it with.
and can go up in CID.

427 cid =4.125 bore 4.0" stoke <(first time the block is used)

434 cid =4.155 bore 4.0" stroke

440 cid=4.185 bore 4.0" stroke

UPDATE:
today i got a email.. this is what was in it.

Hi Jeff,
I know you said you were in absolutely no hurry but I just wanted to let you know that your short block left yesterday via Southeastern Freight Lines. The tracking # is 43581395-1 & you can track it at www.sefl.com. Thanks again & let me know if you have any questions.

Now. remember the last thing he sent me was updated paper work listing a 421
NOT a 427.(see first post)

i orderd and paid for a 427.
they did not get my cam or any of my parts to try out.
i sent them a email reply. letting them know to make sure it's a 427 not a 421.
will not use or take a 421.LOL

looks like it will be at my door on the 24th lol im sure the Fright lines can stop it and send it back,.there Dime not mine.

looking forward to the Email i get back from them Monday.

if you order and pay for an eng.
you better get the CID you pay for.
not what they think you need.
hell why not just send me a 305...lol

did they send me a 421 or a 427, I do not know.?
will have to see what they say Monday, im thinking with the way things are going its a 421.

what amess

I dont know if this has already been said or not but a 427 and a 421 do not share the same bore size either.

The 427 having the 4.125" bore with the 421 having a 4.155 or 4.165" bore.

So possibly he is trying to pawn off a blemished block (where an overbore would clean it up) or maybe even a used block to you. Or maybe its a 4.125" bore thus being a 414 but by him calling it a 421 maybe he thought you would be more willing to accept the motor.

Either way, something is fishy. I would get my money back and head to CNC-Motorsports, they have great deals on 427's.

bore 4.125 stroke 4" =427 (closer to 428)new aftermarket block.
there is no way im getting anything less then the eng I paid For.

I did not order A 421..

my last email to them was letting them know.
the paper work is wrong with 421. and needed to be
listed has a 427.

i have all my emails to them, it's them trying to get me to Buy a 421.
so it's not My prob, if they sent the wrong Eng.

they will just have to make Good, on what I orderd, and paid for,is all.

who knows,monday they could email me,letting me know in fact its a 427,

but i never got the update from the 421 paper work to the 427 paper work,thats Bugging me. we will see.

update:

it is a 427 with all i wanted done to it. and my cam should be fine.
but will check just to make sure.

427 cid
4.125 bore x 4.0" stoke
11.5.1 (listed has 11.9.1)..lol
Forged Pistons
file fit rings
Dart M block
H Beam Rods
forged Crank
and all the Good stuff

if this one runs good. ill get the same with a alum block..(what the heck)