Author Topic: big block heads  (Read 4038 times)

Offline mitch184

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big block heads
« on: July 08, 2005, 02:19:00 AM »
I was looking to get rid of my little peanuts in favor of some larger oval port heads.  I know that the 049's and 781's are supposed to be the best, but what about the 820's or even 427 tall deck heads.  Are the 781's really that much better than the other large oval port heads?  I plan to port match and polish whichever heads I do get and was just wondering whether I really need the more expensive to find heads.  Thanks


Offline roundedline

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Re: big block heads
« Reply #1 on: July 08, 2005, 12:09:00 PM »
The tall deck BBC's are going to have peanut ports also.  ANY head is going to flow better than peanut ports, but they can make power as long as you don't plan to spin past about 5000.  Larger valve are REQUIRED though.

820's are comparable to the 781 in flow, but they have a smaller combustion chamber.  113 vs 118

For the street, stay away from rectangular unless you plan to run high rpms. (above 6500)

At the bottom of this page is a BBC cylinder head testing database of a number of heads that were flow tested.

www.carcraft.com/techarti...index.html

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project


Offline mitch184

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Re: big block heads
« Reply #2 on: July 08, 2005, 09:04:00 PM »
I'm really only looking to make power up until about 5500.  I'm putting about a 213-218 cam in it with headers, intake, 750 carb.  Just basically for towing.  Just wondering how much a benefit the large oval port heads will give me. Also, does that sound like a pretty good size cam for my setup.  it's around 256-262 advertised and around .515" lift.  Thanks


Offline roundedline

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Re: big block heads
« Reply #3 on: July 11, 2005, 09:13:00 AM »
For brute towing, I would probably go with a smaller cam, but that is just me.  The one you listed probably has a redline of about 5000rpms, so I would keep the stock peanut port heads.  They were designed to make power at low rpms for towing.  Adding oval ports are going to move the power curve up.  This is my personal opinion though.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project


Offline RSBAD454

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Re: big block heads
« Reply #4 on: August 15, 2005, 11:15:00 PM »
keep the heads you have if you want pulling power......the peanut ports were designed specifically for this reason. They have a higher velocity at lower RPM. You also want a short duration big lift cam for torque.

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