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#1
01-23-2007, 12:37 AM
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6X Head Conundrum
I have started collecting various Pontiac parts and one of them was a '76 350 to play around with. When I pulled the heads off I looked at the codes on them. The driver side was a 6X-4 and the passenger side was a 6X-8. Is that normal? They both look like original parts for the motor.
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#2
01-23-2007, 12:54 AM
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That is odd.
I have two 6X-4s available. Nether is great but you can look at them if you want. Where in MD are you? |
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#3
01-23-2007, 02:28 AM
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while abnormal, this isnt the first time ive heard of this...i guess the only way to see whats going on is to cc them both...are they cast with a wrong #, or are they really different size heads...hmmmm?
__________________
'74 formula 400, w/shaker (3 scoops) black deluxe interior, '70 406 balanced assembly, .30 trw slugs, moly rings, 4x heads 2.11/1.77 stainless valves, ra 4 cam, e-rpm intake, holley 750 vac. sec, msd hei, hooker headers w/ dual 3'' flowmaster 50 series ending at axle, t400 w/ GM6 convertor, transgo shift kit, b&m starshifter, 3.08 gears, centerlines, 265/50-15 bfg's rear and 235/60-15 front...yes im over cammed but it is still very fun... |
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#4
01-23-2007, 10:14 AM
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More than likely, somewhere in its' life, the engine "hurt" a head. It was replaced by the same casting number. Rebuilders are generally unaware of secondary codes...
Jim |
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#5
01-23-2007, 10:26 AM
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Jack, can you provide the casting dates on both heads along with the Engine Serial Number located above the block code?
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#6
01-23-2007, 10:31 AM
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I can do that when I get home tonight.
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#7
01-23-2007, 03:55 PM
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Ok, thanks. That may help us clarify if it's a production error, or possibly a situation like Mr. P-body suggested.
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#8
01-23-2007, 03:56 PM
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Ok, thanks. That may help us clarify if it's a production error, or possibly a situation like Mr. P-body suggested.
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#9
01-24-2007, 09:34 AM
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The date code off of the 6x-4 is C156 and the 6x-8 is E106. I couldn't get to the block due to time and stuff being in the way but I was told the motor came out of a 1976 Firebird Esprit w/auto.
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#10
01-24-2007, 10:02 AM
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wow how much would that hurt the performance? and could it simply hurt the engine? i would think so
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#11
01-24-2007, 10:02 AM
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Jeff, 8 to 9 weeks is quite a while between the cast dates of the cylinder heads. I would guess that the situation was as Mr P-body suggests, some where at some point in its life the engine had a cylinder head put one bank.
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#12
01-24-2007, 10:16 AM
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I was thinking the same thing after I read Mr. P-Body's post. Thanks for all of the investigation work!
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#13
01-24-2007, 10:24 AM
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Only if you get a chance post the ESN. Since we have an idea of that the 6X-8 was installed after initial assembly, the ESN may better tell us if the 6X-4 is actually an original or if neither head is original to the engine.
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#14
01-24-2007, 02:18 PM
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im fairly certain that all 350s in 76 had the 6x-4 heads.
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#15
01-24-2007, 02:22 PM
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I think Rocky meant that possibly both heads might have been replaced with the wrong ones, and not just the 6X-8 head added.
__________________
John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
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#16
01-24-2007, 11:09 PM
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This is a fairly common proplem as most folks not familiar with Pontiacs see the big 6x on the center exhaust port and assume that the heads match. I've got a nice set of rebuilt heads that are mismatched and of no use unless I can find someone to trade a 6 or 8 with. Anyone close interested?
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#17
01-25-2007, 03:48 PM
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That motor must of ran like total crap!
Unless the 6x-4 head was ported so the chambers matched! One side would have a good amount higher compression. Ugh! |
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#18
01-25-2007, 04:00 PM
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Quote:
I guess I will sell them seperately on eBay. |
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