Stock SBC block w/ 4" stroke?

[4OfaKind]

Guys I am trying to "HIDE" as much displacement as possible in a SBC motor. I know you can put a 3.75" and a 3.875" crank in a stock 350 block. I know aftermarket blocks can easily swallow a big crank, but they are also easily recognizable too. So, can you stuff a 4" crank in a stock block?
The cam is not a concern, I have a solution for that if I go this route. What I want to know is what size rods to use between 5" & 6"? And is a low compression dished piston out of the question because of pin / ring clearance? And are the oil pan rails too thin to clearance for the stroke? What is the affect on cylinder walls of all this extra stroke?

Thanks for the engine building lesson,

Mal

[chicane]

4" in a stock block... gonna be real hard... you have the pan rails to worry about.

You want cid in a small package ?? Go 4.125+ bore with a shorter stroke. HP rules afterall...

[XcYZ]

It's not uncommon to see stock block 434 and 440 SBC's in dirt racing, but the blocks are partially filled with Hard BloK or something similar. As Tom said, you really get into the rails, lots of clearancing.

[Scotch]

Are you trying to hide it, or simply make it fit?

It depends on the application, too. Is it a low rpm street deal, or a high rpm endurance deal?

Is the vehicle heavy or light?

A bunch of stroke will help low-end torque but will take longer to get to a higher rpm level. A big-displacement small-block will require sufficient port size to feed it at the target rpm level, which means you could be getting into offset rockers etc to make it work as well as possible.

Share more info, and more specific details can be researched. Is there a budget for this?

~Scott Parkhurst~

[deuce_454]

A big-displacement small-block will require sufficient port size to feed it at the target rpm level.... Is there a budget for this?
~Scott Parkhurst~

i doubt that you can do the whole engine for what a nice big cube crate SBC costs... a 595 hp 434 from schafiroff costs 9K, less carb and ignition... and it works and comes with a warranty... i sincerely doubt you can develop a big cupe stock block SBC with matched heads and cam.. that just performs at that level with same durabillity.. for that amount of money.. so i guess you have to decice how badly you want to hide displacement

i mean i installed a set of OLDSMOBILE ROCKET valve covers, welded to sbc rails on a friend of mines 31 ford.. and 1 out of 200 spoted that it was a chevy engine...

if you grind the obvious "Dart" casting off a crate engine, paint it orange and install plain jane tin and perhaps even an aircleaner with a 327 sticker.. no one will notice...

and if yoy cheat at the track.. they will catch you no matter which block you use!

[4OfaKind]

It's not uncommon to see stock block 434 and 440 SBC's in dirt racing, but the blocks are partially filled with Hard BloK or something similar. As Tom said, you really get into the rails, lots of clearancing.

That makes sense with the short rod length to stroke ratio; alot of pressure on the cylinder walls. Hard blok is not a route I want to go since I will drive this thing on the street.

Ok but I am confused on the clearancing issue. Dart, World, and others stuff 4" cranks in their blocks. They make thier blocks w/ raised cams and thicker pan rails OK given, but they still use stock deck height am I right? I would think rod ratio and piston pin clearance would be an issue for them.

How are they or their customers getting around that?


Mal

[4OfaKind]

Are you trying to hide it, or simply make it fit?

It depends on the application, too. Is it a low rpm street deal, or a high rpm endurance deal?

Is the vehicle heavy or light?

A bunch of stroke will help low-end torque but will take longer to get to a higher rpm level. A big-displacement small-block will require sufficient port size to feed it at the target rpm level, which means you could be getting into offset rockers etc to make it work as well as possible.

Share more info, and more specific details can be researched. Is there a budget for this?

~Scott Parkhurst~


The application is for a street driven car that will see time on road courses. So the rev range will vary. No endurance stuff, maybe 5 laps at the most. The vehicle will be heavy about 3500lbs.

The heads are a whole different story that will require another thread, so for now assume they are big enough and exotic enough to feed the need. My focus is the ability to stuff a large crank in a small block and how long it will stay in there. Basicly doing it because I can (if I can :_paranoid ).


Mal

[4OfaKind]

and if yoy cheat at the track.. they will catch you no matter which block you use!

The only track I plan to "sneek" in at is the local friday night test and tune. There is always someone willing to donate money to help me break my automotive customizing addiction.

Mal

[XcYZ]

Ok but I am confused on the clearancing issue. Dart, World, and others stuff 4" cranks in their blocks. They make thier blocks w/ raised cams and thicker pan rails OK given, but they still use stock deck height am I right? I would think rod ratio and piston pin clearance would be an issue for them.

How are they or their customers getting around that?


Mal

I had a Dart Iron Eagle tall deck (9.325"). The rails were spread and the cam raised. With a 4" stroke, 6.200" rods, the CH was 1.125". The drawback of the block was that it required a special pan, intake manifold, and adjustable slip collar distributor.

[Scotch]

The application is for a street driven car that will see time on road courses. So the rev range will vary. No endurance stuff, maybe 5 laps at the most. The vehicle will be heavy about 3500lbs.


So a low-rpm torque monster is really what you're after. Pump gas, lots of throttle response, and no need to go past 6,500 rpm or so. How's that sound?


The heads are a whole different story that will require another thread, so for now assume they are big enough and exotic enough to feed the need. My focus is the ability to stuff a large crank in a small block and how long it will stay in there. Basicly doing it because I can (if I can :_paranoid ).


I get it. While I appreciate your angle, the capabilities of the big-inch small-block crate engines out there serve the need. Otherwise, if you really want to build this within the confines of a stock small-block, there's plenty of potential in a 406 to make the kind of power you're looking at.

The thing is...once you decide to go after that other 40-50ci, you really want the raised cam/taller deck to make it work for you. You need to give that crank room to swing and you want to run good connecting rods, and they need clearance too! You don't want to be grinding the rod bolts down or notching the bottom of the cylinder bores if you don't have to. To get a bunch of stroke into a stock block would require these kind of clearancing techniques and while they've been done before, they are also the reason the aftermarket tall-deck/raised cam blocks were engineered in the first place!

So, I'd have to recommend either a very serious 406 or an aftermarket block-based 450-ish inch setup. Based on what I know, which ain't as much as lots of other guys, but is a little more than most, building torque will not be your challenge here. Putting it to the ground will be. I think if you've got 500-550 ft-lbs being put down without tire spin, you will be a happy guy. You can make that kind of power with a very serious 383 or a very good 406. A mild aftermarket block-based 450-plus inch SBC can do even better at lower rpm.

~SP~

[4OfaKind]

I get it. While I appreciate your angle, the capabilities of the big-inch small-block crate engines out there serve the need. Otherwise, if you really want to build this within the confines of a stock small-block, there's plenty of potential in a 406 to make the kind of power you're looking at.

The thing is...once you decide to go after that other 40-50ci, you really want the raised cam/taller deck to make it work for you. You need to give that crank room to swing and you want to run good connecting rods, and they need clearance too! You don't want to be grinding the rod bolts down or notching the bottom of the cylinder bores if you don't have to. To get a bunch of stroke into a stock block would require these kind of clearancing techniques and while they've been done before, they are also the reason the aftermarket tall-deck/raised cam blocks were engineered in the first place!

So, I'd have to recommend either a very serious 406 or an aftermarket block-based 450-ish inch setup. Based on what I know, which ain't as much as lots of other guys, but is a little more than most, building torque will not be your challenge here. Putting it to the ground will be. I think if you've got 500-550 ft-lbs being put down without tire spin, you will be a happy guy. You can make that kind of power with a very serious 383 or a very good 406. A mild aftermarket block-based 450-plus inch SBC can do even better at lower rpm.

~SP~

Thanks SP,

You nailed the requirements above dead on. I guess I should have said "I want 400 ci w/o a bore bigger than 4.060". I looked at my cylinder heads again and if I were to use a 400 block, the cylinder bore and bore centers would be all wrong for the heads and the head gaskets. (Don't ask me to explain; just take my word for it :_paranoid ) I already have a stock block so I was looking at 396 and 401 combos w/ a 3.875 stroke or just maybe a 402 w/ a 4" stroke. Oh well 383 it is for now. :mad:

Thanks again guys for the help.

Mal

[G-Body]

Save yourself the headache and block clearancing and build an awesome little 406 with a 3.75 crank and go woth 6" rods trust me will be all you will want to handle if you can hook it up! ecs mated with a good set of heads 215cc would be just right, this is the exact combo im building for my prostreet keep your cam under 270 ish @.050 with a good single plane and you will A. save your self the price and headache of clearancing your motor and B. will most likely out perform the set up you mentioned beacause increasing the bore to 4.0 will indead at torque but like mentoned not with out problems with cam clearnace etc

[R67Chevelle]

In the fall issue of Chevelle by super chevy the is an article on a 408 chevy that is a stock block with a 4" crank by T&L Engines ( tandlengines.com )

They can go up to 414 on a stock 350 type GM block. Heres their spec sheet. Not bad for under 5K

408 Chevy A-2 510 HP 500 Torque - $4784
•
4.00 stroke 4340 forged steel crank
• 4340 6” H-beam rods
• Mahle forged pistons
• Mahle file fit rings
• GM 4 bolt block
• Dura-bond cam bearings
• Block plug kit
• Oil filter adapter
• Hydraulic roller cam
• Roller timing set
• Custom gasket set
• Chrome timing cover
• Professional products balancer
• Balancer bolt
• Melling high volume oil pump
• Melling oil pump drive shaft
• Melling oil pump pickup
• Hydraulic roller lifters
• Dart or RHS aluminum heads
• 7/16 screw in rocker stud
• Comp cam push rod
• Aluminum roller rockers
• Edelbrock RPM Air Gap manifold
• ARP head bolts
• Chrome valve covers
• Chrome oil pan
• Autolite spark plugs
• Oil filter
• 12 pt bolt kit

Labor

• All parts hand cleaned
• Block sonic checked for thickness
• Block pressure tested @40 psi
• Block stroker clearanced
• Block square decked w/BHJ fixturing
• Aligned hone mains
• Bored and honed w/torque plates
• All clearances checked to the nearest .0001”
• Rotating assembly balanced
• Engine blueprinted w/specs sheet on file
• Engine fully assembled and dressed to customer specifications
• Dyno tested


Blessings,

[68sixspeed]

Here's a picture of what the dart alum. block is notched from the factory and it clears my 4" stroke, 6" rod combo (callies crank/rods) just to give you some idea of packaging. You will need a pan with notches too unless you want to get real creative. (pan spacer, etc.)

It does raise a lot of 'why' questions though on the 350 block-- there is a lot of HP to be gained by that extra 1/8" of bore, not just cubic inches, but in unshrouding the valves. One of the reasons why '358' cid busch/cup motors are big bore, short stroke.

[4OfaKind]

In the fall issue of Chevelle by super chevy the is an article on a 408 chevy that is a stock block with a 4" crank by T&L Engines ( tandlengines.com )

They can go up to 414 on a stock 350 type GM block. Heres their spec sheet. Not bad for under 5K

408 Chevy A-2 510 HP 500 Torque - $4784
•
4.00 stroke 4340 forged steel crank
• 4340 6” H-beam rods
• Mahle forged pistons
• Mahle file fit rings
• GM 4 bolt block
• Dura-bond cam bearings
• Block plug kit
• Oil filter adapter
• Hydraulic roller cam
• Roller timing set
• Custom gasket set
• Chrome timing cover
• Professional products balancer
• Balancer bolt
• Melling high volume oil pump
• Melling oil pump drive shaft
• Melling oil pump pickup
• Hydraulic roller lifters
• Dart or RHS aluminum heads
• 7/16 screw in rocker stud
• Comp cam push rod
• Aluminum roller rockers
• Edelbrock RPM Air Gap manifold
• ARP head bolts
• Chrome valve covers
• Chrome oil pan
• Autolite spark plugs
• Oil filter
• 12 pt bolt kit

Labor

• All parts hand cleaned
• Block sonic checked for thickness
• Block pressure tested @40 psi
• Block stroker clearanced
• Block square decked w/BHJ fixturing
• Aligned hone mains
• Bored and honed w/torque plates
• All clearances checked to the nearest .0001”
• Rotating assembly balanced
• Engine blueprinted w/specs sheet on file
• Engine fully assembled and dressed to customer specifications
• Dyno tested


Blessings,

Hey thanks,

I'll look that issue up for some more details. I knew I was not crazy :willy: when I saw all of World's block specs had stock deck heights but stated they accpeted 4" cranks! Now I have to ponder a decision again 383 or 400? :_paranoid

On another note 67Chevelle I sent you a PM. Did you see it?

Mal

[jsr69]

You might want to check out this book. I found it very useful in helping me decide how to proceed with a big-inch small block that I wanted to build.

http://www.cartechbooks.com/vstore/showdetl.cfm?User_ID=1963572&DS_ID=2&St=907&St2=-90846&St3=29517&Product_ID=3166&DID=6

[XTRMEASURES]

are you still working on this engine build 4ofakind, if so would you have pics.

i have a 400sbc(509#block) that i plan on putting a 3.800'' crank in it. i also plan on having it filled half way with block filler.

good luck with your build

[rocketman]

Very few racers use a stock block unless its a stock type class, all Modified, late model, bracket racers all use aftermarket blocks, many of the street engines I build are aftermarket blocks.

[4OfaKind]

are you still working on this engine build 4ofakind, if so would you have pics.

i have a 400sbc(509#block) that i plan on putting a 3.800'' crank in it. i also plan on having it filled half way with block filler.

good luck with your build

Thanks xtream,

I was just thinking out loud as I plan my motor direction. I have a 350 2bolt block sitting in my garage waiting for me to get done mounting my body so I can locate my engine and trans mounts and start rebuilding the engine.

I just bought a 4L80e last week. After Christmas the car will go in the shop to get body, engine, and trans mounts. Then I have to buy a set of cylinder heads. Engine rebuild will probably start in June. I'm leaning toward a 383, but I won't rule out a 3.875" Stroke w/ a 4.060" bore for a 401ci displacement. Check back then. I will have lots of pics.

Mal

[TonyG]

are you still working on this engine build 4ofakind, if so would you have pics.

i have a 400sbc(509#block) that i plan on putting a 3.800'' crank in it. i also plan on having it filled half way with block filler.

good luck with your build

I have a 400-509 casting block also and was just going to do the same as you but with the standard 3.75 crank. topped with the dart iron eagle heads I already have, a victor jr. and my demon 750 and stab it with a solid roller lunati. and try for somewhere around 10.5-11:1 comp. gotta love 93 octane..