Author Topic: Z/28 production line heads  (Read 1051 times)

Stingr69

  • Hero Member
  • *****
  • Posts: 901
    • View Profile
Z/28 production line heads
« on: July 28, 2023, 01:37:20 PM »
I have a set of very nice "186" heads that look to be completely original and correct except the combustion chambers have the valve un-shrouding machine work on the intake AND exhaust valve walls of the chambers.  Not a deep cut by the exhaust valves but looks to be factory.  No port work mods at all.  The valves are the special GM swirl polished type so I think they are original to the heads.  Have any of you seen this exhaust valve wall cuts before? 

Stingr69

  • Hero Member
  • *****
  • Posts: 901
    • View Profile
Re: Z/28 production line heads
« Reply #1 on: July 30, 2023, 08:41:46 PM »
Do these cuts at the exhaust valve look factory?

cook_dw

  • Hero Member
  • *****
  • Posts: 3981
    • View Profile
Re: Z/28 production line heads
« Reply #2 on: July 31, 2023, 04:36:39 PM »
Here are some photos of heads I have for sale.  One head is uncut the other is.  As far as I know these are a matched pair or at least that is what I was told. 



'186 Heads For Sale on sYc




Stingr69

  • Hero Member
  • *****
  • Posts: 901
    • View Profile
Re: Z/28 production line heads
« Reply #3 on: July 31, 2023, 05:34:22 PM »
All factory big valve heads got the chamber mod around the intake valve at a minimum.  Glad to see you have at least one head that also has exhaust valve un-shrouding that looks to be original.

Who ever did the machine work on the ones you have for sale didn't cut the valve reliefs on the small valve head core.  They really should have cut them if you want them to match.  Need to also examine the throats behind the valves to see if they bowl hogged them open when they added big valves to the one head (originally small valve).  Maybe you can have that done locally?  Hard sell without that. They will not flow the same. 


One head looks like it has steam holes added between the bores?

cook_dw

  • Hero Member
  • *****
  • Posts: 3981
    • View Profile
Re: Z/28 production line heads
« Reply #4 on: July 31, 2023, 06:09:13 PM »
Machine work was done back in 2004 and I would have them checked out if I were gonna use them.  These are sold as is as I'm not messing with them.