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Old 11-06-2004, 03:22 AM   #1
DAMN, I love Big Blocks!
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Location: New Mexico, USA
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BBC "781" Cylinder Head Chamber Volume.

Does anyone have an absolute positive spec for the factory combustion chamber volume on unmodified "781" casting heads off of a 454 BBC? Some books say 109cc, some say 110cc, while others say 119cc. I know the only "true" way is with a burette and a cylinder head cc'ing kit, but I'm just looking to know if anyone has noticed all these varying figures and has an absolute answer. Again, my heads have never been planed or had the chamber fact, they've never even been off the engine! Anywho, thanks in advance, folks.
Marc Bona
Hobbs, New Mexico
1976 1/2 ton GMC High Sierra.
454 c.i.d./ TH400. *Soon to get a mild warming over.*
3.40 rear.
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Old 11-06-2004, 06:03 PM   #2
Grande Rojo
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I've got the same heads and was told they are 118cc but I have never checked.
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Old 11-06-2004, 06:45 PM   #3
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They are 116 to 118 cc. If they've had big valves installed the right way, they'll often be between 112 and 114 cc. If they've been milled, they will be lower. You cannot flat mill those heads more than about 0.030" without hitting the intake valve seat, by the way.
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Old 11-07-2004, 11:57 PM   #4
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i've got two sets in my garage...and a set of "049"s ....these two flow awesome man..... :p

perfect street head....there both 119cc's with stock valves

i remember reading somewhere that the 781's flow around 260 stock

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