I would like to build a 406 sbc. I have been told about 3 different ways to do this. 1 400 block .030. 2 400 block 350 crank with 5.7 inch rods. 3 400 block 350 crank with 6inch rods. Does any one now what works best. I would think stroking it would be best! But which rods? Thanks for any and all answers. Jason 1968 Chevelle.

A 400 block with a 350 crank = 377 cid.

406 is a 0.030 over 400.
Guy

400 block, keep the 400 crank or even better buy a Scat 6" rod 400 crank (will neutral balance like a 350) and Scat's Pro Comp 6" rods, 2-ICR6000-7/16. They are tough as nails, light, and clear most camshafts by a mile.

For your average street/strip car, more cubes wins every time.

Street Car?? Do a 406

A 406 works good with 5.7 rods {thats what we run in our 406}

Race car?? Do a 400 block with a 3.48" or 3.25" stroke crank, parts more available for 3.48" stroke over 3.25". If a race car you will be building 11.5:1+ compression and i would use a long rod such as a 6" rod if N/A to get that piston to dwell @ TDC

What's the difference in "dwell' between the 5.7" rod and the 6" rod? At what crank angle is there more than 0.001" difference in piston position? How about 0.005" difference?

What's the difference in "dwell' between the 5.7" rod and the 6" rod? At what crank angle is there more than 0.001" difference in piston position? How about 0.005" difference?
=
:D :D

I get so tired of going into this I have about given up Mike
I could dig up one of my old posts I suppose,,,,
My favorite internet non issue rears it's ugly head again :pout:

30 over 400 block with 5.7" rods, stock stroke crank will be fine. What you need to focus on is heads, cam and intake combo.

=
:D :D

I get so tired of going into this I have about given up Mike
I could dig up one of my old posts I suppose,,,,
My favorite internet non issue rears it's ugly head again :pout:

Be calm son, take a chill pill and be calm! :thumbsup:

There are about as many ways to go when building a SB400 as you can imagine.
For an all around, dependable, long lasting, street/performance SB400, I have a favorite combo. My experience with SB400s is about 25 engine builds in the past 30+yrs, and here is what I like best.
ANY 400 block, with the 2bolt version being preferred, using studs for the main caps instead of bolts. Pistons are available for .020, .030, .040, .060 over bore. FOR A REGULARLY DRIVEN STREET-PERFORMANCE ENGINE, I strongly recommend a MAXIMUM bore of no more than .040 over!!!! For a street performance driver, hypereutectic pistons are a good choice. Save your money on forged pistons for serious performance applications. Head selection will determine the shape of the piston dome. Flat tops for heads with 76cc chambers, dished tops for 64cc heads. This will keep you in a compression range that will work with today's pump gas.
If the 400 comes with a good factory crank, use it. It may need to be turned, .010-.010, .020-.020, or whatever. If lucky, it may only need to be polished.
You CAN certainly rebuild a SB400 with the short 400 rods, but I prefer to replace them with the longer 350 rods that have been resized with new bolts. This will require a SLIGHT clearancing of the head of the rod bolt which faces the cam. NO BIG DEAL! There is certainly nothing wrong with buying aftermarket rods. FOR A STREET ENGINE THAT IS TO BE A DEPENDABLE DAILY DRIVER, I prefer to avoid the 6in rods. The reason is because the piston is so short, plus the wrist pin hole will be into the ring groove for the oil ring. I just flat don't like this! The shorter the piston is, the more it tends to rock back and forth in a cylinder--------------not so good for a long lasting street-driver. Otherwise, for a limited driven, performance engine, go for the 6in rods.
Camshaft? Well, the sky is the limit, but here is my preference. Your dealing with a 400+cubic inch engine. A 400ci engine can easily handle a bigger profile cam than a 350, so something with a range between .488 and .510in lift will work, AND, you can stay with stock size 1.25in valve springs. If you go with much more lift than that, it may be necessary to step up to 1.45in valve springs (this will require opening up the spring pockets on a factory head). A duration of somewhere between 230deg and 245deg @ .050 lift will make a nice combination that will perform well and you can live with in a street-driver.
For this kind of an engine, I buy all my parts from the aftermarket vendors such as Summit, JEGS, etc, and I shop, shop, shop (learned this from the wife :D ), and I buy generic, in-house parts rather than the big brand name parts such as cams, lifters, oil pumps, timing sets, etc. WHY?????? Well, for example, today's cams are ground on computer controlled machines which have a profile programmed into the machine and then the machine takes all the human error out of the grinding. So why pay for a big brand name cam when a generic in-house cam is most likely ground on the same machine!
REMEMBER, I'M TALKING ABOUT A DAILY STREET DRIVEN PERFORMANCE ENGINE HERE-----------------NOT A HARD CORE RACE ENGINE!!!!!! There's a difference! ;)

LAST
Well, here is what you have been saving your hard earned $$$$$$ for.
Heads. For the best performance, an engine needs to breath efficiently! Put your extra dollars in heads. You can go budget, or you can go crazy.
READ THIS CAREFULLY!!!!
If you use factory Chevrolet production heads, DO NOT use anything later than a set of heads from a 74 model engine!!!!!!!!! (I'm NOT talking about over the counter heads such as Bowtie heads) In 1975 model cars with a SB, GM started cutting corners on the heads, and by 1977, SB heads were thin walled junk----------------which either have cracked, or will crack after you spend your hard earned $$$$$ on them!
If you have a GOOD set of 70-74 SB400 heads (have them thoroughly checked and magnafluxed by your machinist), they can be made into very nice budget heads. You can do a straight valve job on them with new springs, or, you can have the seats opened up for 2.02/1.6 valves (GO WITH STAINLESS VALVES). At one time we all had hard exhaust seats installed in early heads. There is now enough experience in the gearhead world to conclude that it IS NOT NECESSARY to install hard seats in early heads, especially with stainless valves.
With a cam that has over .445 lift, you SHOULD replace the pressed-in studs with screw-in studs. Guide plates are good to add, but not mandatory. You can spend a little extra and have the bowls cleaned up and port match the intake runners. BE CAREFUL SPENDING $$$$$ ON STOCK HEADS, you can end up with the price of budget aftermarket heads.
If you want to step up to aftermarket heads-----------FOR A DAILY DRIVER--------stay with cast iron heads. Since your working with a 400+ci engine, bigger ports/valves would help. I personally like (FOR A 400 ENGINE) something like a DART Iron Eagle with 2.05/1.6 valves and 215cc intake runners. I think their biggest runners are about 230cc, but that is a little too much for a street driver 400. The last ones I bought (after shopping around), COMPLETE, were just over $1000.
Build the engine just as you would build any SB. You'll of course need to have it balanced (usually a little more for an external balanced engine). If the 400 harmonic balancer is good, use it. If not, buy a new one. For an auto tranny (YUK, YUK, YUK) you'll need a flexplate with the added weight. For a manual tranny :hurray:, you'll need a 168 teeth flywheel with the added weight.
ALLLLLLLLLLLLLLLLL normal SB parts/hardware (water pump, pan, timing cover, fuel pump, intake, etc, etc) will bolt right up to a SB400 and it will literally drop right in place for a 283-305-327-350. Everything fits.
FORGET exhaust manifolds (too restrictive), use a decent set of headers. :thumbsup:

Beyond the above, you can go as far or as high as your heart--------and budget permits. But something like the above will perform well, last a long time, run on today's gas and fit most budgets.

Now, a word of caution.
In a heartbeat, you can get into a SB400 REAL DEEP before you know it! And suddenly, you will discover that what you have spent would pay for a nice rebuild on a 454! So, shop wisely for parts, decide up front what you REALLY want out of the SB400 and find a good machinist that is VERY familiar with SB400s. Except for the serious machine work like checking the block, heads, crank, boring, turning the crank, fitting rods/pistons, head work, etc, I do all the small stuff myself at home.

Oh ya, I don't care how well your machinist cleans up your parts for you when he's done----------WASH EVERYTHING WITH HOT SOAPY WATER, BLOW DRY EVERYTHING QUICK--------ESPECIALLY THE OIL GALLEYS AND OIL PASSAGES IN THE CRANK!!!!!!!!!!!! With light oil, wipe out the cylinders and lifter bores to prevent surface rust.
I personally paint the block and heads BEFORE engine assembly. I install an old cam/lifters to keep paint out. After painting, I use a rag/thinner to wipe overspray out of the cylinders/main bores, cylinder deck. I paint the entire engine (lifter valley, timing area, flywheel area) to seal everything. Done it this way on ALL engines for 40+yrs, ZERO problems.

I like what Tom (DZAuto) has to say.

My 406 was with stock heads (1.94/1.6),9.5:1 w/ dished pistons,280H CompCam (230 @ .050/ .486 lift), and 5.7 rods on a stock 400 crank.

Torque monster it was. 13.2 @ 101.7 in a 3450# car.

200cc (2.05/1.6) aftermarket heads (no other changes) went 12.3 @ 110 in same car :D

Has a solid roller now with only a hand full of track pass' (not tuned yet) and times below.

I built my 406 before I ever knew about Tom Parsons...but...his advice above is pretty much exactly how I built my engine.

I have a more-mild cam--224/224 @ .050; and 1.6 rockers. Beyond that, everything he posted is what I did.

Smooth idle; I can out-accelerate normal traffic from a stoplight and never have less than 10" of manifold vacuum.

Heads are everything on a big-inch small block!

If I had it to do over again, I'd have started with a 454. A big-block at the same performance level or even somewhat more power would have been much cheaper.

Here is an example of how I paint my engines.
http://i65.photobucket.com/albums/h219/DZAUTO/enginepaintfrt.jpg

This is the block that was in the boat, 10yrs later.
http://i65.photobucket.com/albums/h219/DZAUTO/100_0081.jpg

Under the valve cover of the 56 Vette about 8yrs later.
http://i65.photobucket.com/albums/h219/DZAUTO/Driveline/dualholes.jpg

And here is inside the 400 in the Chevelle about 9yrs later. Nothing was wrong with the engine. There was a tiny pin hole in the #2 combustion chamber (probably been there for MANY years) which kept leaking water into the cylinder. As you can see, the paint in the lifter area is just fine.
http://i65.photobucket.com/albums/h219/DZAUTO/0091031-R1-020-8A.jpg

You may say there is not a difference between the 5.7" and 6" rod guys but there is. I have ran the same engine combo with a different piston/rod with the same dome and deck height when we went with longer rods and the engine ran best with 200-300rpm more than the 5.7" rod engine

The longer rod engine will move the powerband up, Mike you may not see it on the dyno, i cant say here as i dont use a dyno but i can say in the car with the same heads and all the ET slip will show the 6" rod like 200-300rpm more, mine liked the 6" rod but it had to be turned higher, little difference but when you have a heavy car a little here, there and over there adds up

I like what Tom (DZAuto) has to say.

My 406 was with stock heads (1.94/1.6),9.5:1 w/ dished pistons,280H CompCam (230 @ .050/ .486 lift), and 5.7 rods on a stock 400 crank.

Torque monster it was. 13.2 @ 101.7 in a 3450# car.

200cc (2.05/1.6) aftermarket heads (no other changes) went 12.3 @ 110 in same car :D

Has a solid roller now with only a hand full of track pass' (not tuned yet) and times below.

Doug, if no rain Sunday you gonna be racing at Mason ? We may take the Camaro up to the bracket race Sunday

Be calm son, take a chill pill and be calm! :thumbsup:

There are about as many ways to go when building a SB400 as you can imagine.
For an all around, dependable, long lasting, street/performance SB400, I have a favorite combo. My experience with SB400s is about 25 engine builds in the past 30+yrs, and here is what I like best.
ANY 400 block, with the 2bolt version being preferred, using studs for the main caps instead of bolts. Pistons are available for .020, .030, .040, .060 over bore. FOR A REGULARLY DRIVEN STREET-PERFORMANCE ENGINE, I strongly recommend a MAXIMUM bore of no more than .040 over!!!! For a street performance driver, hypereutectic pistons are a good choice. Save your money on forged pistons for serious performance applications. Head selection will determine the shape of the piston dome. Flat tops for heads with 76cc chambers, dished tops for 64cc heads. This will keep you in a compression range that will work with today's pump gas.
If the 400 comes with a good factory crank, use it. It may need to be turned, .010-.010, .020-.020, or whatever. If lucky, it may only need to be polished.
You CAN certainly rebuild a SB400 with the short 400 rods, but I prefer to replace them with the longer 350 rods that have been resized with new bolts. This will require a SLIGHT clearancing of the head of the rod bolt which faces the cam. NO BIG DEAL! There is certainly nothing wrong with buying aftermarket rods. FOR A STREET ENGINE THAT IS TO BE A DEPENDABLE DAILY DRIVER, I prefer to avoid the 6in rods. The reason is because the piston is so short, plus the wrist pin hole will be into the ring groove for the oil ring. I just flat don't like this! The shorter the piston is, the more it tends to rock back and forth in a cylinder--------------not so good for a long lasting street-driver. Otherwise, for a limited driven, performance engine, go for the 6in rods.
Camshaft? Well, the sky is the limit, but here is my preference. Your dealing with a 400+cubic inch engine. A 400ci engine can easily handle a bigger profile cam than a 350, so something with a range between .488 and .510in lift will work, AND, you can stay with stock size 1.25in valve springs. If you go with much more lift than that, it may be necessary to step up to 1.45in valve springs (this will require opening up the spring pockets on a factory head). A duration of somewhere between 230deg and 245deg @ .050 lift will make a nice combination that will perform well and you can live with in a street-driver.
For this kind of an engine, I buy all my parts from the aftermarket vendors such as Summit, JEGS, etc, and I shop, shop, shop (learned this from the wife :D ), and I buy generic, in-house parts rather than the big brand name parts such as cams, lifters, oil pumps, timing sets, etc. WHY?????? Well, for example, today's cams are ground on computer controlled machines which have a profile programmed into the machine and then the machine takes all the human error out of the grinding. So why pay for a big brand name cam when a generic in-house cam is most likely ground on the same machine!
REMEMBER, I'M TALKING ABOUT A DAILY STREET DRIVEN PERFORMANCE ENGINE HERE-----------------NOT A HARD CORE RACE ENGINE!!!!!! There's a difference! ;)

LAST
Well, here is what you have been saving your hard earned $$$$$$ for.
Heads. For the best performance, an engine needs to breath efficiently! Put your extra dollars in heads. You can go budget, or you can go crazy.
READ THIS CAREFULLY!!!!
If you use factory Chevrolet production heads, DO NOT use anything later than a set of heads from a 74 model engine!!!!!!!!! (I'm NOT talking about over the counter heads such as Bowtie heads) In 1975 model cars with a SB, GM started cutting corners on the heads, and by 1977, SB heads were thin walled junk----------------which either have cracked, or will crack after you spend your hard earned $$$$$ on them!
If you have a GOOD set of 70-74 SB400 heads (have them thoroughly checked and magnafluxed by your machinist), they can be made into very nice budget heads. You can do a straight valve job on them with new springs, or, you can have the seats opened up for 2.02/1.6 valves (GO WITH STAINLESS VALVES). At one time we all had hard exhaust seats installed in early heads. There is now enough experience in the gearhead world to conclude that it IS NOT NECESSARY to install hard seats in early heads, especially with stainless valves.
With a cam that has over .445 lift, you SHOULD replace the pressed-in studs with screw-in studs. Guide plates are good to add, but not mandatory. You can spend a little extra and have the bowls cleaned up and port match the intake runners. BE CAREFUL SPENDING $$$$$ ON STOCK HEADS, you can end up with the price of budget aftermarket heads.
If you want to step up to aftermarket heads-----------FOR A DAILY DRIVER--------stay with cast iron heads. Since your working with a 400+ci engine, bigger ports/valves would help. I personally like (FOR A 400 ENGINE) something like a DART Iron Eagle with 2.05/1.6 valves and 215cc intake runners. I think their biggest runners are about 230cc, but that is a little too much for a street driver 400. The last ones I bought (after shopping around), COMPLETE, were just over $1000.
Build the engine just as you would build any SB. You'll of course need to have it balanced (usually a little more for an external balanced engine). If the 400 harmonic balancer is good, use it. If not, buy a new one. For an auto tranny (YUK, YUK, YUK) you'll need a flexplate with the added weight. For a manual tranny :hurray:, you'll need a 168 teeth flywheel with the added weight.
ALLLLLLLLLLLLLLLLL normal SB parts/hardware (water pump, pan, timing cover, fuel pump, intake, etc, etc) will bolt right up to a SB400 and it will literally drop right in place for a 283-305-327-350. Everything fits.
FORGET exhaust manifolds (too restrictive), use a decent set of headers. :thumbsup:

Beyond the above, you can go as far or as high as your heart--------and budget permits. But something like the above will perform well, last a long time, run on today's gas and fit most budgets.

Now, a word of caution.
In a heartbeat, you can get into a SB400 REAL DEEP before you know it! And suddenly, you will discover that what you have spent would pay for a nice rebuild on a 454! So, shop wisely for parts, decide up front what you REALLY want out of the SB400 and find a good machinist that is VERY familiar with SB400s. Except for the serious machine work like checking the block, heads, crank, boring, turning the crank, fitting rods/pistons, head work, etc, I do all the small stuff myself at home.

Oh ya, I don't care how well your machinist cleans up your parts for you when he's done----------WASH EVERYTHING WITH HOT SOAPY WATER, BLOW DRY EVERYTHING QUICK--------ESPECIALLY THE OIL GALLEYS AND OIL PASSAGES IN THE CRANK!!!!!!!!!!!! With light oil, wipe out the cylinders and lifter bores to prevent surface rust.
I personally paint the block and heads BEFORE engine assembly. I install an old cam/lifters to keep paint out. After painting, I use a rag/thinner to wipe overspray out of the cylinders/main bores, cylinder deck. I paint the entire engine (lifter valley, timing area, flywheel area) to seal everything. Done it this way on ALL engines for 40+yrs, ZERO problems.

A 400 will run great with GM heads. We have a 400 in the Camaro with 283 castings we had at the shop. We had 2.02 valve installed and bowl ported them. No runner or exhaust work. Milodon valves. Milled to bump compression up to 11.5:1 USING KB flat top 2 valve relief pistons with 5.7" 350 rods and stock 400 crank. Heads were cut for Crane 1.46" valve springs with steel retainers

We run a solid flat tappet cam spec'd at 256/264 @.050 .545/.563 105° lobe seperation installed @ 102° Intake Centerline. Vic Jr. intake with a 850BG modified by us

ATI powerglide transmission, 4,500rpm stall with transbrake and 32" rear tires with 4.88 gears. Best pass thus far 10.436 @127.4mph. Car weight is 2780 with driver after pass

So yes you can make a 400 run well with cheap cheap parts. We have WELL over 100 runs on it this time. Im not scared to say the KB hypers have 400-450+ runs on them

You may say there is not a difference between the 5.7" and 6" rod guys but there is. I have ran the same engine combo with a different piston/rod with the same dome and deck height when we went with longer rods and the engine ran best with 200-300rpm more than the 5.7" rod engine

The longer rod engine will move the powerband up, Mike you may not see it on the dyno, i cant say here as i dont use a dyno but i can say in the car with the same heads and all the ET slip will show the 6" rod like 200-300rpm more, mine liked the 6" rod but it had to be turned higher, little difference but when you have a heavy car a little here, there and over there adds up
=
Butch
If it moves the power band up how the hell am I not going to see it on the dyno?
Are you telling me that with all the varibles of going down a track including air conditions, traction, shift points,,,,, the list goes on that you are going to see a few HP improvement better than you will under controlled conditions on a dyno?
That is just insane :sad:

I have been building these things since before you were born & I can tell you without a doubt that you are not going to see any real measurable difference in power between a 5.7 & a 6" rod simply because of the rod length change
And you for sure are not going to move the powerband 300RPM, this is a function of the heads & cam not rod length regardless of what engine you want to discuss.

You can read & repeat all the crap that is floating around forever & this is not going to change
If you saw a difference with the so called longer rod there was something else going on
Like how much lighter did the piston get?
How much did it change the cam timing?
Now what happens if you can run slightly more duration with the "short rod" because it comes off of BDC slower?

This is not just my opinion, it comes from both my experiences as well as many other builders
Ever hear of Darin Morgan or a place called Reher Morrison?
They tested rod lengths for GM some 20 years ago with the same results.

I am not saying I don't like the longer rod just that I know what it does & does not do when you are talking about any reasonable change.

As for your more top end with the longer rod,,
Here is a direct quote from Isky with a better explanation than I could do

"In fact, this may surprise you, but I know of a gentleman who runs a 5.5" Rod in a 350 Small Block Chevy who makes more horsepower (we're talking top end here) than he would with a longer rod. Why? Because with a longer dwell time at BDC the short rod will actually allow you a slightly later intake closing point (about 1 or 2 degrees) in terms of crank angle, with the same piston rise in the cylinder. So in terms of the engines sensitivity to "reversion" with the shorter rod lengths you can run about 2-4 degrees more duration (1-2 degrees on both the opening & closing sides) without suffering this adverse affect! So much for the belief that longer rod's always enhance top end power! "

=
Butch
If it moves the power band up how the hell am I not going to see it on the dyno?
Are you telling me that with all the varibles of going down a track including air conditions, traction, shift points,,,,, the list goes on that you are going to see a few HP improvement better than you will under controlled conditions on a dyno?
That is just insane :sad:

I have been building these things since before you were born & I can tell you without a doubt that you are not going to see any real measurable difference in power between a 5.7 & a 6" rod simply because of the rod length change
And you for sure are not going to move the powerband 300RPM, this is a function of the heads & cam not rod length regardless of what engine you want to discuss.

You can read & repeat all the crap that is floating around forever & this is not going to change
If you saw a difference with the so called longer rod there was something else going on
Like how much lighter did the piston get?
How much did it change the cam timing?
Now what happens if you can run slightly more duration with the "short rod" because it comes off of BDC slower?

This is not just my opinion, it comes from both my experiences as well as many other builders
Ever hear of Darin Morgan or a place called Reher Morrison?
They tested rod lengths for GM some 20 years ago with the same results.

I am not saying I don't like the longer rod just that I know what it does & does not do when you are talking about any reasonable change.

As for your more top end with the longer rod,,
Here is a direct quote from Isky with a better explanation than I could do

"In fact, this may surprise you, but I know of a gentleman who runs a 5.5" Rod in a 350 Small Block Chevy who makes more horsepower (we're talking top end here) than he would with a longer rod. Why? Because with a longer dwell time at BDC the short rod will actually allow you a slightly later intake closing point (about 1 or 2 degrees) in terms of crank angle, with the same piston rise in the cylinder. So in terms of the engines sensitivity to "reversion" with the shorter rod lengths you can run about 2-4 degrees more duration (1-2 degrees on both the opening & closing sides) without suffering this adverse affect! So much for the belief that longer rod's always enhance top end power! "

Mike,

In bold, this is a fact not repeating crap. This is stuff we have seen in engines in our car.

In blue, This may very well be. It may have been due to the piston being lighter. Not saying its not, you may have hit the nail on the head {about 50grams lighter off the top of my head}. How much did it change the cam timing, Well the centerlines were left alone along with the cam BUT the valve would have more lift with the piston at TDC due to the longer dwell which may have gave us more port velocity through BDC to keep the air/fuel mass moving? Is this what it caused, I dont know. Maybe it was a combo of this and lighter parts from the longer rod

In bold blue, Come on Mike !! Thats like asking you if you ever heard of Lee Sheppard or Warren Johnson.

[/color]

Mike,

In bold, this is a fact not repeating crap. This is stuff we have seen in engines in our car.

In blue, This may very well be. It may have been due to the piston being lighter. Not saying its not, you may have hit the nail on the head {about 50grams lighter off the top of my head}. How much did it change the cam timing, Well the centerlines were left alone along with the cam BUT the valve would have more lift with the piston at TDC due to the longer dwell which may have gave us more port velocity through BDC to keep the air/fuel mass moving? Is this what it caused, I dont know. Maybe it was a combo of this and lighter parts from the longer rod

In bold blue, Come on Mike !! Thats like asking you if you ever heard of Lee Sheppard or Warren Johnson.
=
Butch,
My opinion along with many others I regard as a lot smarter than myself & who's opinion I do not take lightly is
Rod length within a reasonable ratio is nothing but fodder for "internet experts"

Your post above is exactly my point,
You cannot say the rod changed the RPM range of the engine with a rod length change that is damn near impossible to graph which is what you did.

You cannot say this is what you have seen in your car so it is the rod, you have no clue if it was the rod.& as you know I hate misinformation misleading confusing information
So again, & since you like bold stuff,,,, :p
Within the bounds of anythiing we are discussing here rod length within a reasonable ratio is a non issue
As for the cam timing if you left it alone it changed slightly as far as the engine is concerned
Read what Ron Iskenderian wrote
How do you explain this if a longer rod supposedly makes

Now tell you what
Since you mentioned Warren Johnson,, ask his opinion on changing rod length within a reasonable range to gain power from just the length of the rod ;)
I already know the answer,,, I have heard it along with the opinion of some of the top NASCAR crew chief's in a roundtable discussion at the ATEC conference a number years ago
And I have stated it on this forum many many times.

BTW, this is part of why I say you are not going to quantify these kinds of changes on the drag strip, way too many variables to see a couple of HP
This is dyno territory and even then it is only with ABA testing you can be reasonably sure of the results

You like to have stuff to study go play with these for a while :p

http://www.chevelles.com/forums/showthread.php?t=168167

http://speedtalk.com/forum/viewtopic.php?t=2066&postdays=0&postorder=asc&start=0

http://speedtalk.com/forum/viewtopic.php?t=1914

http://speedtalk.com/forum/viewtopic.php?t=2398

http://speedtalk.com/forum/viewtopic.php?t=2177

http://speedtalk.com/forum/viewtopic.php?t=2066&postdays=0&postorder=asc&start=0 (http://speedtalk.com/forum/viewtopic.php?t=2066&postdays=0&postorder=asc&start=0)

I thank you all for the great info. Also so for all the chit chat, you all sound like a fun bunch. I think I can build something for my needs off of what you have told me. I again thank you all. Can't wait to go to the strip. Cordova Dragway Park. Cordova Ill. You all have a good one. P.S. you know it Tom #3 forever. Jason 1968 Chevelle.

I thank you all for the great info. Also so for all the chit chat, you all sound like a fun bunch. I think I can build something for my needs off of what you have told me. I again thank you all. Can't wait to go to the strip. Cordova Dragway Park. Cordova Ill. You all have a good one. P.S. you know it Tom #3 forever. Jason 1968 Chevelle.
=
Jason
If this is primarily a street deal build the 400" engine, there is no good reason to give up cubic inches by destroking with a shorter stroke crank
You can build it with 5.7 or 6" rods & with a forged crank it will internal balance
If you use a cast crank none I know of will internal balance without using the 6" rod without added expense & my preference is to always internal balance if possible

I almost always used to recommend the 6" rod combo but this has changed as the newer cranks balance internally with 5.7 now with no issue with a decent piston so either one is going to be fine with the 5.7 slightly less expensive due to piston pricing.
There are slight advantages to either setup which tend to get way overblown on the internet except possibly the piston weight thing & even this is a non issue for most anything we are doing here.

So,,, pick your poison & have fun,,, :beers:

Either way I would recommend you use decent parts, the Scat cranks with the Scat Pro Comp 7/16" bolt capscrew rod is my favorite as it has a ton of cam clearance even with standard base circles.

If you are going to build this & I can help you with any of the parts like a complete balanced rotating assembly or whatever just shoot me an email & I will be glad to see what I can do, we have done a few for folks here & we balance everything in house, I do not sell the so called "mail order" assemblies. ;)

Mike's balanced Scat crank is jewelry :)

Mike's balanced Scat crank is jewelry :)
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Thank's Rick, gald we could help you :beers:
But it might be a bit heavy to wear around your neck :D