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Discussion Starter #1 (Edited)
Hey guys. a feller in my area who runs a body shop, built a 472 smallblock chevy for his girls El Camino . At the time when his daughter told me i thought she was telling me wrong numbers. I checked it out and her dad laughed and said i knew her friends would say it couldnt be done. Since then I have read alot about these big bore smallblocks. Still i would like yall to explain to me how this is done. I get tired of hearing "350". I have a complete 350 that i would like to build into somthing a little less traditional.

Thank ya
 

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Yes, you have to use an aftermarket block of course, but you use a 4.25 stroke and somewhere around a 4.2 bore.

Adam
 

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big displacement SBC

That engine would be based on a 400 SBC, as it would be extremely difficult to get that kind of displacement out of a 350, the bore being a major limitation. It could be done by boring the engine out to the water jackets and using larger bore sleeves, but the cost isnt going to be miniscule.

The 400 has a 4.125 bore and with a .060 over bore would have 4.185 bore, with a stock stroke of 3.75 would yeild a 413 CID displacement. There are stroker kits on the market to get as much as 440 cubes out of them, but they arent low cost.

Running a 60 over bore, or bore of 4.185, would require a stroke of 4.29 inches to achieve 472 cubic inches.

It sounds like a no standard production block, one that is aftermarket in order to accomplish that.
 

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The largest you can go with a production/factory 400 block is 430 (434) and that is not recommended. There are durability issues.

Last I heard the largest small block people were building was right at 460". All of these large small blocks (427, 434, 454, 46*, etc... use an aftermarket block).

Using a an Olds 350 "Rocket" block you can also build a large cube small block.

As Kieth said to try to do it with a factory block the cost is a HUGE issue. You are better off just buying an aftermarket block. They are designed for big displacements. They are better castings for this type of engine.

From a production 350 the largest you can got is 391ci this is done with an offset ground crank. They are not popular because they are not as good as 383's The 391's are not a good performance engine.

Royce
 

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472 from 400

I totally agree with Camaroman. One of the biggest problems with going with these huge stroker kits in the SBC is that they have a 9 inch deck height, and to go with such long strokes creates problems with rod and piston combinations , having to run extremely short rods creates problems with piston skirts, the bottoms of the cylinders, as well as severely increased side thrust on the cylinder walls, due to the small rod stroke ratio.
You are better off to go with an aftermarket block or seek out a production block that can tolarate such modifications, without costing you the entire national budget.
 

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Bil Mitchell has a 454 kit. I wouldn't use it. The rings are way up into the piston pins. I would rather stay with my 5.7" rod 400 and have it last a while.

If you want 472 cubes why not just go big block?
 

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Discussion Starter #12
Ok. Fellers i was interested in 472 for how impossible it seemed. "why not go big block?" Boys, its gotta fit in a Vega ....lol. Im wanting to build a durable streetable smallblock somthing a little less tradional. Im not even set on lots of cubes, just want to try sopmthing different. I have a complete stock 350. Let me know what u think , thanks for all the great info.
 

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Hi folks, first post for me but given I have run a 454 small block for the past 4 years and freshen it with new details almost every year I thought I could add a little value to this thread.

The only way you are really going to get super big cubes with durabiity our of a small block is with the aftermarket blocks out there. A few details make these blocks much better than a standard 400 core. First the pan rails are spread to give clearance for up to a 4.250 stroke crank, which you need for displacement over 454, I run 4.125. Next the deckheight is taller, up to 9.5, so you can get a loooong rod in there and keep the pin height down. Next the oiling system is priority main. Next bore sizing, depending on brand can be up to 4.25 or so. Next the cam tunnel is raised so clearance with the big cranks is not an issue, plus most come with big block bearing sizes for the cam as well so running .700 lift like I do on the street is no problem. Strength is also far superior with an aftermarket block, basically throw whatever you have the balls to throw at it for power and it will take it. Finally weight, my bare aluminum block weighs 98 lbs, nearly 100 less than a standard aftermarket cast iron small block.

There are a ton of good reasons to build a big small block and a ton of good reasons not to. I did it just to be different and beat up on the big blocks at the track. If I had to do it over again I'd do a Brodix aluminum big block with 18 degree heads and a turbo.

A reason though to do it is with good heads and around 11:1 compression you'll smack the chassis dyno silly with 500 ft lbs of torque at 3000 RPM and spin up around 550 to 600 HP on the top, with pump gas. Then you always have the nitrous to pelt those pesky turbo big blocks.

Building a motor like this and living with it year to year does take maintenance. I typically will tear it down every year for inspection. Of course my buddies that run serious big blocks do that as well. Making big HP has those downsides.

To do a build up like this the two blocks I would consider would either be the Dart or the Brodix.
 

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Humble opinion

In my humble opinion, I would suggest, since you are wanting to use a Chevy engine, either go with a 350 with a 383 stroker kit, or run a 400.
 

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Discussion Starter #16
Bracketeer, I love the sound of the 377. how do they run? pros and cons? it has to be quick AND different. The idea sounds great let me know more please. thanks you. How would it run with a lopin cam and such?
 

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Dart Tall Deck Iron Eagle 4Bolt HP Block with Raised Cam & Splayed Steel Billet Caps

Dart Tall Deck? Iron Eagle 4 bolt HP?

Which is it? A Dart or Iron Eagle?

What's a Dart Tall Deck?

What's an Iron Eagle HP block?

Why have I never heard of this before?
 

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A 377 is a destroked 400, so you would have to get a 400 block first.

Adam
 

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These are killer Sb's , i wouldn't go bigger than the 427 , 434, built with the GM Rocket blocks, These are no longer available from GM ? and the Motown Blocks about $1800.00 for the block only. add the rest of the lower end and machine work $5000 to $12000 depending on the strength of the parts used. Starting to see a lot of the 434s at the track , most folks will not tell you, Its just a 350 or 383 !! Right! Add a good set of aluminum heads and thats a Lot of weight saved over The BIG Block for sure. I have found one used Motown Block last summer for $800 so they are around used if you look.
 

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johnsongrass1 said:
Dart Tall Deck Iron Eagle 4Bolt HP Block with Raised Cam & Splayed Steel Billet Caps

Dart Tall Deck? Iron Eagle 4 bolt HP?

Which is it? A Dart or Iron Eagle?

What's a Dart Tall Deck?

What's an Iron Eagle HP block?

Why have I never heard of this before?
The Iron Eagle is a cast iron high performance block made by Dart.
The Iron Eagle name differentiates it from the Dart aluminum version.

A tall deck is simply that, a taller deck than stock. Stock deck height is 9.025. A tall deck would be either 9.325 (.300 taller) or 9.5. The taller deck height gives you room to run a longer rod to keep rod ratio reasonable with a bigger stroke.

I don't know why you have not heard about ti before. These blocks are used for serious build ups in late model, dirt modified, drag race, and street applications. These blocks retail from $2000 up to over $4000 depending on sbc, bbc, iron or aluminium versions.
 
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