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Hello. I have a '67 Mustang (San Jose built) with a 289/2bbl. I am now in New Mexico and want to remove the smog system as I have no plans to move back to California. I did some research and got some plugs for it only to find out that they were way too small for the openings I need to plug. I recently found out that I probably have one of the original thermactor systems and was told to just use freeze plugs with a non-silicon sealant to close those off. As best as I can tell it would require a 7/8 size freeze plug, but I can't find any locally. I'm attaching a picture and hope that helps. Does anybody know if there is a better way of plugging up the hole, and whether or not 7/8 is the correct size? I don't want order something online until I'm assured of what I'm needing.


Thank you.
 

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Okay. I'm still looking for some help with these. I'm attaching a couple more pictures, in addition to the one I posted with my previous post, hoping someone is familiar with this set up that could help me figure out how to plug up the holes. The picture in the previous post shows where these are located, and the two with this post show both the inside of the hole and the bolt that goes into it. From what I understand, these apparently are not the typical thermactor holes to plug as there are only two of them, one in the side of each head. The plugs I was told to get don't seem to fit as they would be for the other set up.

Help!!

Thank you.
 

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The early Thermactor systems were on Cleveland built engines where each cylinder had an air pipe connection. What you have is the standard Thermactor hardware used on the Windsor built engines that had a single pipe connection on each cylinder head. Windsor didn't start making engines until halfway through the '66 model year. The plumbing to each cylinder for those was machined inside each head. The plug kits are usually for the 8 holes of a Cleveland engine.

That connection originally had a brass gasket seal to the head that Bob Mannel describes as 0.92 x 1.18 x 0.021" thick. After it was attached the entire connection you show was painted Ford corporate blue as was the entire engine. If you can't find commercial plugs for those holes you will need to have a machine shop make a pair of cylindrical plugs of the appropriate size and attach them with 5/16" bolts similar to the ones you removed. They may have to also make the brass gaskets for you. Its a fairly easy job for anyone with a lathe.

To make it easier you could cut brass plugs that combine the plug and gasket function into one chuck of metal. Its not like you plan to ever remove them.
 

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Discussion Starter #4
The early Thermactor systems were on Cleveland built engines where each cylinder had an air pipe connection. What you have is the standard Thermactor hardware used on the Windsor built engines that had a single pipe connection on each cylinder head. Windsor didn't start making engines until halfway through the '66 model year. The plumbing to each cylinder for those was machined inside each head. The plug kits are usually for the 8 holes of a Cleveland engine.

That connection originally had a brass gasket seal to the head that Bob Mannel describes as 0.92 x 1.18 x 0.021" thick. After it was attached the entire connection you show was painted Ford corporate blue as was the entire engine. If you can't find commercial plugs for those holes you will need to have a machine shop make a pair of cylindrical plugs of the appropriate size and attach them with 5/16" bolts similar to the ones you removed. They may have to also make the brass gaskets for you. Its a fairly easy job for anyone with a lathe.

To make it easier you could cut brass plugs that combine the plug and gasket function into one chuck of metal. Its not like you plan to ever remove them.
Okay. Thank you. Now I have something to go with. :) Thank you very much!!! :)
 

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Okay, this is what I finally ended up doing, and so far it seems to be working great. I want to post what I did just in case someone else has the same issue as I did with this.

I got four 1 1/4" hardened metal washers that the bold would go through okay. I also got two bolts 3/4" shorter than the original bolt and some "Form A Gasket" stuff.

I used two washers on each side, in addition to the small washer that was on the original bolt, and put some of the "Form A Gasket" stuff between each washer and between the washers and the head. I hand-tightened it first and let it set for a few minutes before tightening them up further.

So far it seems to have worked great with no apparent exhaust leaks.

Hope that helps someone else. :)
 

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I did one that way too. I used orange high temp silicone on mine. No leaks. I've seen them plugged with a 7/8 ths pipe plug too. Other than the clutter it's surprising how little the power is improved when it's removed.
 

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I did one that way too. I used orange high temp silicone on mine. No leaks. I've seen them plugged with a 7/8 ths pipe plug too. Other than the clutter it's surprising how little the power is improved when it's removed.
Yea, I heard there wouldn't be much of a performance gain from doing that, but I wanted to get rid of the clutter since I no longer have to have it. Also makes working in the engine compartment easier. :)

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Not a chance back in the day. Now the rule in California is '75 and later must be original and working plus bi annual inspection/certification.
Cars that are '75 and older are completely smog exempt in California. No inspection is required. Which means you can do whatever you want with it with no penalty (other than noise complaints?)

Unless that's what you meant when you said '75 and later, I may have misunderstood.
 

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Just as an aside...your '67 would have been legal with no smog equipment, even in California.

https://www.dmv.ca.gov/portal/dmv/detail/vr/smogfaq
You are wrong. The car needed the equiptment to be legal IN 1967.. Now in the present day, things are different, as you probably meant to say the '67 is legal NOW, not "WOULD HAVE BEEN" legal in '67 without. It

It's impossible for us to tell from your use of the past tense, if you meant past as in "1967" or past as in, the recent past, say " last week your car was legal without the smog equiptment".

Z
 

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To the OP, I'd check over in th concours forum to see if any of those guys are needing your smog take offs. They like to present the cars just as they rolled off the assembly line.

ConcoursMustang Forums - Index

Z
 

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Cars that are '75 and older are completely smog exempt in California. No inspection is required. Which means you can do whatever you want with it with no penalty (other than noise complaints?)

Unless that's what you meant when you said '75 and later, I may have misunderstood.
Yup, '75 and later. ('75 to current must retain full smog earlier , none required.
 
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