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Discussion Starter #1
Its Sunday, the garage is warming up, and I have been pondering Larger Dave's endearing references to 400 c.i. sbc's. If you have 2 paths to choose from, a 400 based 427 sbc maybe starting with a Dart block or a 427 based on Mitchell's sbc/LS hybrid which way would you go? A no bottle, no boost, enough gear, torquer able to go on a power tour if wanted.

I look on my harley motor as being the last 2 cylinders whacked off a sbc. Its a bored 88 running flatties, .002 in the hole with a .030 cometic gasket, with the heads done to get around 10 static with a HD 204 cam straight up. Its a torque monster easily ridable for an old guy too lazy to downshift. Looking for the same in the above choice.
 

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The Dart set up is great but when you consider what the LS motors have to offer in all their refinements based on the original sbc , the choice is clear.
The LS is a different animal . Also you need to determine where you are in this decision, part bought or on hand and what is yet needed vs. the LS set up. If you have nothing of either, I would go LS.
 

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Agree with Don, but, should one add in the $ for changeover of ancillary systems and equipment?
Or is this scenario starting from an empty engine bay?
Always go for the stroke - torque wins on the street.
 

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I will agree with Don. Dart 427 SBC if you want/need to stay "old school".

BUT, no need to go 427 in a LS motor....one guy on another site with a 403" LS is pushing 700+HP and not really that radical of a build. A 427" LS would be cool, and might as well just go LSX454 from GM for the $$$$, that is unless you can find a LS7 at a good price l:)

Here are the dyno results from my latest build: 707 HP at 7100 RPM & 578 Ft. Lbs. of torque at 5500 RPM.

403"
4.005" LS2 Block
Callies Compstar 4"crank and 6.125" Compstar rods
Bullet CP 11.5:1 compression flat top pistons
Dart Pro1 LS3 heads milled to 65 cc.
FelPro 1161-.041 MLS gaskets
247/259 110.5+3.5 .660"/.650" Cam Motion Low Lash Roller
Edelbrock Victor Jr. intake
835 CFM 4150 Holley
1 7/8" ARH headers
Melling 10295 pump and a Mast Oil Pan.
 
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Discussion Starter #5
Starting from an engine bay set up for a sbc. The common element in the motors is the lack of an LS block.
 

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Discussion Starter #7
Now dont go fogging up the discussion with logic. The crate motor option is excluded.
 

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I've had dreams of a 400 SBC build since the late 70's and have been holding a block since then. The choice is an easy one for me. Old School Rules!

Jeff
 

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Maybe the thread should be started over with a set of rules and what is on hand in starting this project?
But, this said, I like the crate engine because it's proven, comes with oil, broken-in, EFI, and has a warranty.
 

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Discussion Starter #10
All i am interested in with this is a comparison of the two possible build paths in the original post. sbc based 427 with a likely aftermarket block and a Mitchell hybrid LS 427.
 

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You can not compare the LS-x series of motors to the earlier SBC design. It is the cylinder head that makes power, not the short block; and the LS enjoys twenty five years of engineering research to reduce emissions. We as hot rodders generally care less about emissions, but getting the engine to run stoichiometrically at any RPM offers an advantage. The days of a big block roaring down the strip putting out more black exhaust smoke than a diesel are long gone.

Yes a carburetor equipped motor will make more overall horsepower than a car equipped with EFI (not because the carb is better at metering fuel, but because it is far more forgiving of a radical cam). But the EFI equipped motor enjoys constant monitoring that keeps the air fuel at predefined limits, adds or removes spark based upon engine load and if it hears any detonation, as well as having the latest innovation in internal combustion engines; variable cam timing.

I would not buy the Bill Mitchell LS block that allows you to build an old school 427 in a standard SBC block package that accepts the then newer LS-1 heads for the reasons I pointed out above; as the advantages of EFI over old school carb and vacuum advance distributor.

The ability to change the cam's timing dynamically alone nearly doubles the power of a 324 cid (5.3L) small block (compared to a 210 horse 327 from 1967) so that I can not tell from the driver's seat that it isn't a ZZ502 under the hood (except for the lack of a poor idle and better gas mileage). It's power when combines with a six speed tranny will spin my rear posi shod in 275R55x20 tires at will off the line, and tows as if it where a 454.

I still do not like EFI (especially drive by wire), but I can respect the inherent advantages of the new Gen six free breathing heads combined with variable cam timing, and coil on plug ignition timing.

There is one package that hasn't been addressed and that is the short lived SB II reverse cooled SBC from 1994 through 1996. It was an EFI tuned port 350 that motivated a two ton barge of an Impala to impressive performance levels. It could easily be converted to a 383, and not so easily converted into a 406-421 small block with some machine work and creative programming of the factory PROM that controls the OBD II computer. Once again like with the Apple II GS and the Mac you have two engineering teams developing advanced technology in total isolation of each other simultaneously to developed a competing product.

Just because the LS won out doesn't negate what Chevrolet engineers accomplished with the SBC II. Get rid of the questionable Opti-Spark distributor, and you have a reliable efficient small block that shares technology; if not necessarily the same parts (because of the reverse cooling) with the conventional SBC package. It could be a cheap build platform that could yield impressive results, and be a unique engine for car shows. (I'm sure there would be a lot "what the heck is that questions?"). You don't have to retain the EFI as the distributor gear is still on the cam and there is a socket in the block to accept a standard HEI distributor with a carburetor on an old school VORTEC intake manifold (what would have been used on the light trucks).

Big Dave
 

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Dollar for dollar of course the ls wins. I like when old cars use what they came with but that's me. They put ls engines in everything these days but most of them had bad engines to start with so of course the ls is a major improvement. Our old Camaros came with good engines even the straight 6. I am not sure exactly what answer you are looking for?
 

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Discussion Starter #13
Not really looking for an answer, just the discussion. I am a good ways along in the process of bringing my 67 back to life yet i have decided what i want to do for a motor. This scenario cant go on much longer. I have a couple of 350's i could throw in it. At this point i know better what i dont want then what i do. I dont want a bbc, fly by wire, hydraulic clutch, automatic trans. It kinda funny when you go to a car show and hear , its just another LS conversion. I dont mind doing something different, prefer it. I dont care about a warranty. I would likely assemble whatever it is myself. Mitchell block caught my eye. I worried more about it from its rep than the engineering Dave mentioned. I think the latest version of it can run the electronic pack and newer top end should you choose but not vvt. I have to look into the SBll. That came and went while i was twisted up in Harley's.
 

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Different ?

SBC with some SB2 heads :yes:

 

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Know how to make 700 horsepower with a NASCAR SBC2.2 Chevy small block engine?

Pull one of the spark plug wires off!

The 18° degree Chevy heads are phenomenal.





And the price for them is dropping like a stone since the R07 replaced them in racing nearly a decade ago. Joe Gibbs racing has two sets of ported and massaged heads bare for $2000, though you can buy brand new a set of new Pro-Filer Air Strike 12° SBC Heads for about the same price (once again bare). Smaller teams that are not as famous as Joe Gibbs or Hendrix have them for sale for less complete.

Might have a few hood clearance issues either way if you have a flat hood but it would be worth it in my opinion.

Big Dave
 

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Not really looking for an answer, just the discussion. I am a good ways along in the process of bringing my 67 back to life yet i have decided what i want to do for a motor. This scenario cant go on much longer. I have a couple of 350's i could throw in it. At this point i know better what i dont want then what i do. I dont want a bbc, fly by wire, hydraulic clutch, automatic trans. It kinda funny when you go to a car show and hear , its just another LS conversion. I dont mind doing something different, prefer it. I dont care about a warranty. I would likely assemble whatever it is myself. Mitchell block caught my eye. I worried more about it from its rep than the engineering Dave mentioned. I think the latest version of it can run the electronic pack and newer top end should you choose but not vvt. I have to look into the SBll. That came and went while i was twisted up in Harley's.
What kind of power are you looking for. I would imagine building omne of those 350's(maybe with a stroker kit) could easily get you 500 hp. Put a power adder on it and even more yet.
 

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Basically it comes down to preference and what you like. Obviously the new LS motors are better on fuel, reliable and if you ever need a fix you can just roll up to the local GM dealer. While all of that is great and all, I am still an old school guy at heart and when I pop the hood, I want to see that old school look. Like mentioned above, everyone is doing the LS thing and rightfully so to each his or her own. But one thing I will say, that rumble and feel of that old school motor cannot EVER be replaced!
 

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The Bill Mitchell hybrid is expensive to build. More then a full LS by far without the advantages of a complete LS.

Your don't wants rule out an LS. Your wants lead you logically to a Dart based 427. The next decision is heads. The rest is easy.
 

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Big SBC 427" would be fun,
mine's only a 421" and a can be a handful with my street set up and little 275-35-18" tires if you attempt spirited acceleration in 1st or 2nd.
I have a lot of $$ in the engine,it snowballed on me a bit, if I could do it over,

600+hp ls for sure.
 
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