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I just bought a 1968 firebird. It has the 350 hood and Im trying to id the engine. I found a stamp on the right side of the engine below the head. PXN. I also found a id # to the left of the timing cover 28l141143. My heads are marked 01. I think these are junk 301 heads from the 70"s. I'm hoping that the block is not a 301.Can you use 301 heads on a 350? Any help will be greatly appreciated.
 

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301 150 Hp Px4,px6,pxl,pxn
Not being smart, only honest, 301`s make good boat anchors, that`s about all there good for.
 

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Pontiac Heads

I just bought a 1968 firebird. It has the 350 hood and Im trying to id the engine. I found a stamp on the right side of the engine below the head. PXN. I also found a id # to the left of the timing cover 28l141143. My heads are marked 01. I think these are junk 301 heads from the 70"s. I'm hoping that the block is not a 301.Can you use 301 heads on a 350? Any help will be greatly appreciated.
A good head for a pontiac 350 was the #48 series. You can get very good results from a 6x or 4x head. I have 6x heads on a blown 428 pontiac and 6x heads on a 455 built to super duty specs which's runs 12.01 in the quarter mile in a 1969 pontiac grand prix. You can get these heads all over cheap. But I agree replace the 301 parts.
 

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Head I.d.

vettedreams2001 said:
I think the casting numbers on a lot of pontiacs were on the back top near the tranny.
THEIR IS A CASTING NUMBER IN THE MIDDLE OF THE HEAD OBSERVED ABOVE THE EXHAUST MANIFOLD AREA. EXAMPLE MARKINGS..6X,4X,670,13,16,6H ETC. USUALLY THE CASTING SIZE IS ABOUT 5/8 INCH IN SIZE. SOMETIMES IF YOU HAVE HEAT SHIELDS FOR THE HEAT RISERS TO THE AIR CLEANER THEY WILL BLOCK THIS VIEWABLE NUMBER.
 

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JDG 38 pontiac said:
A good head for a pontiac 350 was the #48 series. You can get very good results from a 6x or 4x head. I have 6x heads on a blown 428 pontiac and 6x heads on a 455 built to super duty specs which's runs 12.01 in the quarter mile in a 1969 pontiac grand prix. You can get these heads all over cheap. But I agree replace the 301 parts.

6x heads have a reputation for being a great flowing head, pontiac guys are always drooling over them, but I wouldn't say they're all over and I wouldn't say they're cheap. 5c heads are the same casting but with hardened seats for unleaded fuel. they are as common as mud and few people realized they are the same as a 6x. not to go off on a tangent here, but it might be something to keep in mind if you're looking for heads.
 
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