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RIP (12/27/60-7/18/15)
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767 Posts
Discussion Starter #1
Always wondered, what makes a 400 HO special from a regular 400?
thanks !!!:cheers
 

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64-67 Expert
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8,569 Posts
An 068 cam instead of an 067, and open element air breather, and special high flow exhaust manifolds. Oh yeah, the block code is different, too....WS instead of WT for the stick cars. For automatic cars, YS is the base 400, I forget what the HO auto code is, but it's easily looked up.
 

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Former Moderator
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2,895 Posts
I'm not sure if it's applicable to all years, but I believe HO's had large valve heads. My 69 has #48's which I believe they only put on stick shifts and Ram Air 3's. 428 used the same heads as well as the 350 HO that year. Pontiacs used so many different head castings it's almost insane.
 

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Former Moderator
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3,523 Posts
an 068 cam instead of an 067, and open element air breather, and special high flow exhaust manifolds. Oh yeah, the block code is different, too....ws instead of wt for the stick cars. for automatic cars, ys is the base 400, i forget what the ho auto code is, but it's easily looked up.
yz ........:)
 

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64-67 Expert
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8,569 Posts
All standard and HO GTO 400's had the same, big valve heads........#670's. Even some of the early ram air '67's used this head.
 
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