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

I'm cross posting from the CRG site as I'm not getting traction on this question. 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 Heartbeat City. Contrary to 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)

Wish I could help. I ran into the same issue as you. There must be a few out there. However, if it is used, it will likely get dinged pretty good when removed. I suppose you could get one out using a 1 inch wooden dowel instead of steel or brass as the drift.

What resto shop installed the wrong one ?

PM Sent.

how about machining the part to take out the stamp??

Eddie, machining a stamped plug to eliminate the stamp is a definite possibility if I can't source a nice, unstamped replacement plug. As we don't have a lathe in our shop it would be a job I'd have to outsource.

I got lucky some years ago and ordered them from McMaster Carr. Ordered 25 (smallest quantity to order) and half of them didn't come with the stamp. Sorry I told a few friends and they all got scooped up. That stamp in most of those freeze plugs is actually pretty deep. Some were almost 30 thousandths deep.

lloyd, send me a few and let me try at my machine shop

"That stamp in most of those freeze plugs is actually pretty deep'" Yes, I've experienced that trying grind it off.

Is it possible to pour some filler, resin, glue etc. on the stampings and then restore the freeze plug? Try to fill the stampings in and then sand out?

Would think normal expansion & contraction of a freeze plug would foil this over time.

i would machine the plug - at least try......send me a few

Thanks for the offer Eddie!

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

New intake expansion plug stamping, 1 1/4" unplated steel, no mfg markings:
https://farm5.staticflickr.com/4283/...9dc8ca8b_c.jpg

New Stamping vs Jobber zinc plated plug
https://farm5.staticflickr.com/4284/...97f2766c_c.jpg

Reverse side of factory original 472 manifold with expansion plug (unplated steel)
https://farm5.staticflickr.com/4262/...722613f9_c.jpg

They look great.

Well done. Now you can sell the extra plugs to the shop that restored your intake.


Jason

Installed.

https://farm5.staticflickr.com/4295/...732f6032_b.jpg

nice job!

So... you gonna offer some of your extras for sale on this site?

x2

Yes, I will, I have more plugs and to my knowledge they are not available repro or NOS in this size . Its a nice, high visibility correct detail. Send me a PM if you want one.

Lloyd.

Yes, send me a PM.

Lloyd.