1969 Z/28 Camaro "472" Intake Manifold Expansion Plug

[Edgemontvillage]

The original, steel intake expansion plug from my 472 intake manifold was lost. I sent the intake to a well known restoration shop for re-skinning and was surprised to see the replacement plug they used was stamped with manufacturers' marks.  The original, factory installed 1 1/4" plugs had no marks so what I now have is incorrect. I have been trying to source a correct replacement steel plug and have ordered them from eBay sellers as well as HBC. Despite the item photos they all arrive with some form of manufacturers' stamping marks. I have even tried to grind out the stamp however the result is not suitable for a quality restoration. The original 302 from my Z/28 which is being rebuilt needed a set of replacement frost plugs which I was able to source from a Corvette restoration parts supplier with no manufacturers' stamping marks however I've been unable to locate a correct replacement intake expansion plug. Anyone have a confirmed source for unstamped, 1 1/4" steel intake expansion plugs?  

472 Intake with an incorrect replacement steel expansion plug showing stamped manufacturers' marks highlighted (source: eBay)



Typical frost / expansion plugs with stamped manufacturers' marks (source: Google images)

[Edgemontvillage]

Anyone?

[ZLP955]

Not aware of a source for an unstamped plug, but I'm sure a CNC machining company could run a few off for you if provided with one of the replacements to ensure dimensionally correct. May cost a little up front, but a limited batch could probably be sold to like-minded restorers to recoup some $.

[68camaroz28]

Lloyd, don't know about manifold plug but for everyone's knowledge the "frost plugs" as you called them are still or were available from GM and still have the same look as originals with no other stampings.

[Edgemontvillage]

Lloyd, don't know about manifold plug but for everyone's knowledge the "frost plugs" as you called them are still or were available from GM and still have the same look as originals with no other stampings.

Chick, thanks, I've taken care of the frost plugs (casting plugs) however still trying to solve for the 1 1/4" intake manifold plug. Enio (Eddie) offered to machine a stamped plug to remove the stamping for me which sounds like a possible solution. I'd like to find an unstamped one.

[Edgemontvillage]

I received notice from Photobucket that their free 3rd party hosting (photo linking) is now fee for service only at $400 per year - wow.  I need another solution!

[KevinW]

I use fototime, links are still working for me

[Edgemontvillage]

I received this photo of an original, unrestored 472 intake (underside view) with its factory installed expansion plug. As with the original plug from my intake its unplated steel.


I wasn't able to locate a new or suitable mint expansion plug (1 1/4", steel, unplated, unstamped) contacted a small freeze plug company who did a custom run for me. I have several available.

[Edgemontvillage]

Out with the incorrect...

[ZLP955]

Looks good Lloyd

[Edgemontvillage]

Still experimenting with image hosting alternatives to Photobucket. Here are some Flickr hosted photo renderings:

New intake expansion plug stamping, 1 1/4" unplated steel, no mfg markings:
 

New Stamping vs Jobber zinc plated plug (haven't unwrapped the reskinned manifold...)
 

Reverse side of factory original 472 manifold with expansion plug (unplated steel)
 

[BULLITT65]

that looks good. WTG seeing this project through. Sometimes it the little things that get ya...

[Charley]

Maybe you can sell some of those plugs to the resto shop that put the wrong plug in your manifold so others don't have to do what you just did.

[Edgemontvillage]

Maybe you can sell some of those plugs to the resto shop that put the wrong plug in your manifold so others don't have to do what you just did.

Interesting thought, however if anyone needs a correct plug I still have plenty!

[Edgemontvillage]

Correct Plug Installed