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10-03-2017, 02:37 PM
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#1 |
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Registered User
Join Date: Mar 2016
Location: Bransgore. Dorset. United kingdom
Posts: 61
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427 big block aluminium heads
Hi guys, just bought a set of 3946074 heads date stamped late 73, bought em off a ford guy who had no idea what he had for just shy of 450 bucks. I can see they've been ported but I'm just trying to figure out how much they might have been milled and if they're even usable. any help is much appriciated
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10-03-2017, 02:45 PM
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#2 |
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Registered User
Join Date: Mar 2016
Location: Bransgore. Dorset. United kingdom
Posts: 61
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Re: 427 big block aluminium heads
Can get more photos if required
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10-03-2017, 06:17 PM
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#3 |
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Moderator
 
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,204
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Re: 427 big block aluminium heads
These heads have obviously been machined down "decked" to an extremely low tolerance on the intake valve verge....the area of the valve closest to the deck of the head.
Take a look at the pic I have attached, showing brand new un-decked heads,,,there is at least 1/8" of deck surface in the intake valve area. These heads may very well be ok if a very very experienced engine builder assembles the engine...the piston deck clearance will have to be "down the hole" to prevent piston to valve interference. There may also be block area contact requiring a small machined cutout crescent in the top of the block deck itself...again, to ensure the valves dont hit an immovable object. If its too good to be true, it usually is.... 
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10-03-2017, 07:08 PM
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#4 |
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Registered User
 
Join Date: Feb 2007
Location: Star Valley, WY
Posts: 2,038
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Re: 427 big block aluminium heads
i cant tell for sure but those look flat milled, can you tell? id rather have them angle cut. has the intake side been cut? either way that valve proves those have been cut a lot.
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Steve 1971 GMC Longbox. Full Roller Stroker 489 w/ FiTech EFI, Chris Straub Cam/NV4500/205/D60/14B w. Grizzly Locker and 4.11's. 2" Lift on 33's |
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10-03-2017, 07:49 PM
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#5 |
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Moderator
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,204
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Re: 427 big block aluminium heads
They actually look like they have been reverse angle milled as the depth in the chamber looks stock, but the intake edge is non existent...
These will need at least a 60 - 80 thou in the hole slug, plus I suspect some crescent relief on the intake side of the bores... Even a thick gasket wont compensate for that much... If you look close on the surface you can see where the head gasket is so close to the chamber, it will be hard to keep these sealed... Oh well...
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10-03-2017, 08:52 PM
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#6 |
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Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,891
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Re: 427 big block aluminium heads
Go get your money back. Somebody ruined a good set of heads
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10-03-2017, 09:05 PM
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#7 |
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Registered User
Join Date: Oct 2006
Location: Orland Park Il
Posts: 2,041
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Re: 427 big block aluminium heads
He knew what he had.....
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68 GMC C3500 Longhorn DRW 67 Chevy C10 LWB 90 Mustang Gt 90 Mustang Notchback |
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10-03-2017, 10:08 PM
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#8 |
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Registered User
Join Date: Nov 2006
Location: KINGSPORT,TN.
Posts: 3,035
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Re: 427 big block aluminium heads
I have a n.o.s. Set of c-port gm aluminum heads in gm boxes , had em for several decades
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I BELIEVE IN JOHN 3:16 |
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10-03-2017, 11:19 PM
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#9 | |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,724
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Re: 427 big block aluminium heads
Quote:
 And I found the Lost Dutchman Mine!...umm "D" ports?
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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10-03-2017, 11:25 PM
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#10 |
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Registered User
Join Date: Nov 2006
Location: KINGSPORT,TN.
Posts: 3,035
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Re: 427 big block aluminium heads
No c ports
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I BELIEVE IN JOHN 3:16 |
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10-04-2017, 05:10 AM
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#11 |
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Registered User
Join Date: Mar 2016
Location: Bransgore. Dorset. United kingdom
Posts: 61
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Re: 427 big block aluminium heads
The guy was owed a lot of parts for his falcon so he cleared out the guys workshop of what he could unfortunately it looks like he thought he picked up some heads, turns out he just had a couple of paperweights ���� and then this chump bought em �� thanks again guys
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10-04-2017, 01:06 PM
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#12 |
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Registered User
Join Date: May 2009
Location: Canton, Tx
Posts: 175
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Re: 427 big block aluminium heads
try to CC them and see what your combustion chamber is. the make thicker head gaskets to help with that type of thing. I would carry them to a machine shop before I just gave up on them.
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10-04-2017, 03:45 PM
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#13 | |
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Registered User
Join Date: Oct 2006
Location: Orland Park Il
Posts: 2,041
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Re: 427 big block aluminium heads
Quote:
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68 GMC C3500 Longhorn DRW 67 Chevy C10 LWB 90 Mustang Gt 90 Mustang Notchback |
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10-04-2017, 04:43 PM
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#14 |
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Registered User
Join Date: Nov 2006
Location: KINGSPORT,TN.
Posts: 3,035
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Re: 427 big block aluminium heads
probably gonna need custom pistons to run these heads
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I BELIEVE IN JOHN 3:16 |
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