Joe, or any body else, can you help me id these heads. They are 1401177 aluminum heads with casting dates of 310611 and 308611. What is this date. Joe. you gave me the 076 heads info in the past, is this the newest casting. They have 2.19 and 1.88 valves in them. Can you give me the flow rates. they are said to have 114 cc combustion chambers that are open chamber. Do these heads have round or D shaped exhaust?
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Re: 1401177 L88 heads
Jeff-----
I think that you may have the casting number incorrect. Most likely, it's 14011077. This is the CASTING number for the GM PART NUMBER 14011076 cylinder head.
These heads have 2.19/1.88 valve size, 118 cc combustion chamber, 295 cc intake runners, rectangular intake ports, and "D-shaped" exhaust ports with lower "vane".
The 14011076 cylinder head was a SERVICE replacement head for the earlier casting number 3946074 and PART NUMBER 3946072 cylinder head. However, they were not identical heads. The 3946072 cylinder head had the same valve size, combustion chamber volume and intake port configuration, but the intake runners were 325 cc and the exhaust ports were round.
The 14011076 cylinder head was never used on a PRODUCTION engine; it was available in SERVICE only. It became obsolete about 4 years ago.
For a while there was no replacement for this cylinder head from GM. Recently, however, a replacement has been released. This cylinder head is GM PART #12363408. This head is the best of all of the previously described cylinder heads. It uses an advanced-design semi-open combustion chamber of 118 cc, 2.19/1.88 valve size, 315 cc intake runners, INTERLOCKING HARDENED VALVE SEATS, and "square" exhaust ports. This head does have a somewhat different external configuration from earlier cylinder heads, but all original parts will bolt up to it. This is THE one to use.
I don't have any idea what the decoding would be for the dates you've provided. However, it's pretty immaterial since these heads were NEVER used in PRODUCTION. They were produced from about 1982 until about 1996.In Appreciation of John Hinckley -
Re: Joe, what is the casting number
Joe, can you give me the casting number of the GM part # 12363408 if it differs from the part number. Can i purchase this set of heads from GM? Can you tell me the part number of the 71 LS6 iron heads? someone is selling a pair of these with a part number ending in 990 and are they the same as the aluminum 3946074 heads. Joe, thanks alot for all of your help today and in the past, I know that all of your info is right on every time. I am trying to make my 71 LS5 an LS6 clone and want the aluminum rectangular port heads that will work the best regardless of the casting number as the number will not make it run any better or worse.My LS5 has an LS6 bottom end and cam already, why not go all the way. I want to make sure that i get the correct heads the first time. Thanks again, you are the best!!Comment
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Re: Joe, what is the casting number
Jeff-----
The CASTING number for the PART number 12363408 heads is 12363401. However, several different heads are made from this casting. The 12363408 is a DIRECT REPLACEMENT for the 14011076 head. However, there are even better finished heads made from the 14011076 casting. The other ones have larger valves and/or CNC-machined ports. You won't find too many of these heads for sale here-and-there; they're all very recently released GM heads, so GM will be about the only source at the present time. There are several different ones available; some sold as bare heads and some complete. The GM #12363408, which is the direct replacement for the 14011076, is a bare head. This particular head is not sold complete. These heads are NOT INEXPENSIVE. The 12363408 BARE HEAD GM lists for $849.00 each. The others are more expensive.
The cast iron equivalent of the LS-6 head(and, in fact, the direct successor head to the LS-6 Chevelle cast iron head) is GM #6260482. This head has casting number of either 6272990 or 14096188. It currently GM lists for $445.54 each.In Appreciation of John HinckleyComment
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