1968 thru 1974, excluding 1970 smog pump head hole cup size

[Scot Minesinger]

Working on a 1974 Cadillac and the smog pump was removed, but the head holes are not plugged, and I would like to take care of that. 

Does anyone know what size and where to buy them?

["Cadillac Kid" Greg Surfas 15364]

Measure it Scott. If I am not mistaken I have found a couple different sizes on these castings.
Greg Surfas

[The Tassie Devil(le)]

If I am not mistaken, one of your American coins fits perfectly in there.

It was mentioned some time ago, and I mean a really long time ago.

Bruce.

[Scot Minesinger]

Will measure and report back.  This is probably a 74 engine because it has the smog pump head holes and an EGR, only year for both I believe.  Where do you buy the cups?

[cadillacmike68]

Are you referring to the holes in the heads? I just use freeze plugs.

Remember the fun I had with the plugs in my 1968?

http://forums.cadillaclasalleclub.org/index.php?topic=156624.msg437548#msg437548

[Cadman-iac]

Working on a 1974 Cadillac and the smog pump was removed, but the head holes are not plugged, and I would like to take care of that. 

Does anyone know what size and where to buy them?

The ones In my 69 472 and also my 72 use a 11/16" cup plug, like a small freeze plug. Any decent parts store should have them or be able to get them for you.

[Cadman-iac]

If I am not mistaken, one of your American coins fits perfectly in there.

It was mentioned some time ago, and I mean a really long time ago.

Bruce.

I just checked, it's a dime that fits the hole. Never thought of trying that. Definitely a cheaper fix!

[The Tassie Devil(le)]

That's the one.

Here is what I did to fill the hole when I removed the AIR stuff.

I cut up the crossover, and welded up the fitting and simply placed them in the hole.

On the Left side, one has to use the retainer as it assists in the alignment of the Power Steering Pump.

Bruce.

[Scot Minesinger]

The holes are there, but the air piping is gone.  Does anyone know where to  buy the cups?

[Cadman-iac]

The holes are there, but the air piping is gone.  Does anyone know where to  buy the cups?

Places like Napa, or another reputable chain, but there are also some really good independent companies that you can find them at.

[35-709]

If you can't find them at NAPA (which would surprise me) you can get them at the old MTS - now Cadillac High Performance.
https://cadillachighperformance.com/

Also eBay ---
https://www.ebay.com/itm/11-16-Steel-Expansion-Freeze-Plugs-Cup-Style-Plain-steel-Lot-of-20-Pcs-/151893522219

Should be EZ to find.

[cadillacmike68]

I got mine at NAPA and a couple,spares at mt local Cadillac dealer. 

Now I can't remember where I put them.

Somewhere on the garage wall...