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#1
05-08-2005, 08:11 PM
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I looked closer at my 6X heads again today and realised
that it wasn't an X on the little pad but an angle #4 that looked like an X. Sorry for the misleading info,I still want to know if they used leftover early 70's 400 BLOCK to build these W72 engines. Thanks! Pontorquer |
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#2
05-08-2005, 08:11 PM
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I looked closer at my 6X heads again today and realised
that it wasn't an X on the little pad but an angle #4 that looked like an X. Sorry for the misleading info,I still want to know if they used leftover early 70's 400 BLOCK to build these W72 engines. Thanks! Pontorquer |
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#3
05-08-2005, 08:43 PM
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No early engine parts used in the 78 -79 engines.
what you have is the 6X-4 heads that all the W72's came with.
__________________
72 Firebird, sorta green, mostly gray with a red trunk lid. 14.9 @ 95mph in the Quarter mile. Street tires, highway gear open rearend. PRO Series True Street 15 second index winner 2003, 2004 Cordova, Il. 
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#4
05-08-2005, 09:09 PM
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I was just curiousto know why the block casting code was XX 481988 (481988 like early 70's 400)
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#5
05-10-2005, 04:56 AM
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Yhe XX block is a 78-79 only block, it was only used for the W72 engines.
__________________
66, 68, 69, 70 GTO's, 76, 77, 78 Y82 TA's 79, 80, 81 Y84 TA's 77 Macho 5, 79 Macho Turbo 22 78 W72 Y88 79 W72 W66 W50 |
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#6
05-14-2005, 08:45 PM
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I took my 400 apart for inspection a couple days ago and was impressed with the thickness of the main webbing and caps, beefier than the 76 firebird 400 I had before ! This engine was previously rebuilt with .030" 8 reliefs casting pistons.There is a ring scratch on one of the cylinder wall,hopefully it will clean up with a hone. Too bad the bearings were not in good shapes and the crank has been cut 030" on rods and .020" on mains. What the heck, I will trow a lighter 350 crank into it ! I am pretty convinced that the 481988 XX were leftover
early 70's block that they use for the hipo W72 400's.The 6X#4 heads were rebuilt as well and are still in excellent shape. PONTORQUER |
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#7
05-15-2005, 04:59 AM
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For unknown reasons Pontiac used the earlier style 400-cid blocks for the last run of the W72 engines. I do not think these were leftover earlier blocks from early 1975 as Pontiac produced 43,579 W72 Firebirds with the XX 481988 casting number. The casting of these blocks would have occurred between Aug 1977 and Nov 1977. The 400-cid was being phased out of production at that time.
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#8
05-26-2005, 10:50 PM
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xx 400 blocks were in 1970 (first year for xx, i have one, 979914)drilled for 4 bolt, and 1971... rated at 265 hp...the lowest 400 hp ratings for those years...not hi perf...those are the only years im showing...
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'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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