Well fellas it turns out on the backside of the intake manifold there was a machined threaded hole that I did not remove anything from when I removed the intake manifold from the car. After removing and reinstalling the intake manifold twice and adding red RTV I still could not get it to idle. I cut off the ends to all of the vacuum lines to give them fresh beginnings, still nothing. So I started looking over the intake manifold for something I had missed and noticed a hole in the back. I stuck my screwdriver in it and it went straight to the bottom. So I wadded up a piece of paper and stuffed it in the hole and the car started right up and idled perfectly. I spoke to Russ and he asked me for the number on the intake manifold which turns out that it was from a 1966 engine. So the first picture here is the number on the intake manifold, the second is the whole and the third is a downloaded picture of the intake manifold. If anyone can tell me what this little Supply plug with the two little nipples is for I would appreciate it.

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I have a few 66 cars, and no hole there.  plug it.  

Wow That is one beautiful engine bay !

1966 California Cadillacs came with the Air Injection Reactor (A.I.R. System) to help reduce emmissions. This required an air pump, and about a dozen other parts that interfaced with the carb, air cleaner, cylinder heads. etc. This required modified components including the carburetor, where a tube for the A.I.R. system was fitted on the back of the carb in place of where you would normally have the vacuum fitting for the power brake vacuum hose and transmission vacuum modulator pipe. On 1966 A.I.R. equipped cars, this brake vacuum and transmission vacuum was instead pulled off a fitting off the back of the intake, which is what you have. 
I have seen several of these, and you can just plug it, or use for vacuum for brake and transmission and plug the fitting off the back of the carb. Either way it is just an extra outlet for intake vacuum. 

I can't believe the car has been running without it all these years.

I guess whatever plugged the hole fell out when you were working on the intake. Hopefully it is outside the manifold instead of inside.

Joe D 

That is one hell of an  interesting story and  big surprise for sure 

Very glad you solved this unusual problem  about  a 66 manifold having this additional  hole 

Glad the car is back to running as it should 


Thank you Tony as you can imagine I am quite pleased.

I've pulled in more than one CA 1966 intakes with a plug like that. There ya go! It would be curious to see what you had in there before?.... piece of cork, cousin Vinnie's cut-off middle finger, or someone's pork sausage! Didja ever take a gander back there or take some pics when the engine was rebuild and put back together?

I didn't think to do that. But I will take a look and see if I have any pictures that would show that area. But I'm pretty doubtful.



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