461X SBC Heads and other Rare SBC Heads

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461X SBC Heads and other Rare SBC Heads

from SpeedTalk other Thread Link :
https://www.speed-talk.com/forum/viewtopic.ph ... 75#p728375

this "Rarest 461X version of the various 461X versions" have these Features :

[1] = Largest Intake Port Volume CC's out of the other 461X versions
NHRA Legal Specs for 461X are :
Intake Port Volume CC's = 172.0 maximum ( very rare #461X = 173.5 to 175.0 CC's making it Illegal for NHRA as is )
Exhaust Port Volume CC's = 64.0 maximum

the largest Intake Port Volume CC 461X version actually CC's larger than NHRA Legal Specs
so i'm guessing NHRA never saw or measured that ultra rare version ???

the 2 Intake Ports i measured with "Kimax brand Class A Buret " purchased from Mr. Red Anderson, then Div 4 Tech Director
one = 173.5 CC other = 175.0 CC
did not CC the other Head , nor any Exhaust Ports, but i measured the width of the Exhaust Port + wrote all the info ontop the Heads
20+ years ago ... a little faded to read, but still can make out the text

[2] Contoured Intake Valve Guide Boss in Bowls ( no other #461X versions i've seen have a contoured guide boss )
[3] Lower + wider Floor at Apex , with a maxed out Roof height at the Short Turn
[4] the widest Pushrod Pinch width of all the cast-iron OEM SBC Heads produced

this "Rarest 461X version of the various 461X versions" have these other unusual Features :
[1] have little "x" stamped on the center machined Pad in valve spring area side of Heads
[2] has Fin coming off that machined Pad , along with little "x" stamped on the center machined Pad
[3] Large unmachined as cast integral Exhaust Valve Guide Boss
[4] plain casting number
[5] has NO machine mark or notch on that center Fin pad

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Best of the #461X versions and rarest , have the 461 numbers orienated this way on the bottom of the Intake Runners :
461 Number orienated Lengthways or horizontal across the Head (upside down in this view )

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Contoured Intake Valve Guide Boss in Bowls :

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Contoured Intake Valve Guide Boss in Bowls ( another view ) :

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2nd the best largest 461X version has ragged Intake Valve Guide Boss in Bowls :
....... i installed 0.502" solid Steel Guides w/Phosphor/Bronze Liners in this Head , but you can still see the Guide Boss shape difference

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Little "x" stamped of the center Pad and the Fin coming off that Pad ( of the rarest #461X version )
Note: that Pad has no machined notch or marks on it

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Little "x" stamped of the center Pad and the Fin coming off that Pad
Note: that Pad has no machined notch or marks on it
..... another view angle :

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the Famous "X" in the end Cylinder portion of Head :

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only the "61" numbers out of the 461 number ....in the other end Cylinder portion of Head :

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the "461" numbers orienated differently on the bottom of the Intake Runners on another X version :
...... 461 numbers orienated vertically across the bottom of the Intake Runners

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the plain wide center Pad without a Fin on the regular #461 non-X versions :

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Little "x" stamped of the center Pad and the Fin coming off that Pad
Note: that Pad has no machined notch or marks on it
..... another view angle :

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Compare the top 2 previous Pictures against the 2nd Best Largest Port Volume CC Intake Port #461X versions :
this #461X version has a little machine notch in the center Pad , and no little "x" stamp, and still has the Fin off the Pad

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the following rest of the 461 Pictures are about the various ways GM/Chevy cast-in the "casting numbers" on the different #461 versions :
1st = the very Best + Largest #461X version casting number

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