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Hey, Is a 400 sbc bored 30 over a 427, Wanna know

 
swaluda
V-6 Camaros rule!
Posts: 71
Joined: 11/12
Posted: 02/10/13 11:27 AM

Confused  Confused Do you need to do anything to the crank? When i was a tad younger i had a big  block ( truck motor ) 427 with work done it came to 550 horse at the flywheel in a 64 chevelle ss. My heart shudders to think i only paid $1500 for the car with the stock motor, another 1200 for the motor work. All GTO interior. Midnight Blue, Cragars all around, Jeez, those days were good for prices. Well today i find myself with a body off restore on a old plymouth ( 1950 ) I need to fab a bunch to convert to sbc and thought a 427 sbc might be a good choice. Just dont know how to get there. Callin on my Buds to give me a clear road with a goal of about 450 horse, give or take. Dont really want to bore too much, hear a 400 block dont like it and tends to run too hot. 5 speed trans. 373 gears in back, 26 inch tires, shorty headers, might try long headers though, quarter race cam with 58cc 2.02 etec heads. 750 double pump carb, dual plane edelbrock intake, Hydraulic rollers Thanks for your input Stan in NE Pa.  

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68scott385
I mow my lawn and find Chevys
Posts: 1994
Joined: 10/09
Posted: 02/10/13 11:32 AM

400 sbc bored .030 is 406

std bore 400 w/4" stroker crank is 427

400 bored .030 w/4" stroker crank is 434  
68scott385 68scott385 68scott385

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76Skylark
Big Block power for the win
Posts: 868
Joined: 12/11
Posted: 02/10/13 12:09 PM

Cubic Dollars ...It's all about the Machine work, so start with a dart Block Made for that purpose,but it can be done.  

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swaluda
V-6 Camaros rule!
Posts: 71
Joined: 11/12
Posted: 02/10/13 12:50 PM

whats the stroke of a standard 400 crank, and can we get to a 4in stroke by cutting the crank. Stan  

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68scott385
I mow my lawn and find Chevys
Posts: 1994
Joined: 10/09
Posted: 02/10/13 01:05 PM

The standard 400 stroke is 3.75". You'd have to ask your machinist if he can offset grind it .250" and expect it to live to 6000rpm. If it was me, I'd buy an aftermarket 4" stroke crank. You'd also have to clearance the factory GM block to accept the longer stroke's bigger swing. Places like the bottom of the cylinder bores and the oilpan rails. It CAN be done but the doer better know what they're doing, like NOT hitting water jackets, or the block will be scrap metal.  
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tuffnuff
Moderator
Posts: 7841
Joined: 12/09
Posted: 02/10/13 02:13 PM

+1 Scott
There can be rod bolt/cam lobe interference.,. small base circle cams address this, to some degree.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

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Dave632
I mow my lawn and find Chevys
Posts: 2253
Joined: 07/08
Posted: 02/10/13 02:42 PM

If you are going to try for that much stroke I would suggest an aftermarket block.
You are much less likely to hit water with one of those.
I went with a Dart big M on my last 4 & 3/4" BB stroke. I did my own rod clearance and did not have any problems. They are built with more strength in important areas too.  
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swaluda
V-6 Camaros rule!
Posts: 71
Joined: 11/12
Posted: 02/11/13 10:43 AM

Hmmm. Is it the same issues of putting a 400 crank in a 350, or are we talking about a different ball game here. I realize on the 400 crank on 350 engines the block needs a fine grind where the crank might rub, and also the rod ends might slap the cam and need a touch taken off. Hopefully not enough to throw balance to hell. Are the water jacket locations the same as the 350? A Dart block would be nice but the price difference between a stock GM block and a Dart is quite a bit. I'm talking an old 70's block, pre smog, old style mill. Maybe a 3 grand build. Thanks Stan  

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