seeking 66 Riviera 425 smog removal advice .

Discussion in ''Da Nailhead' started by JayTee, Sep 1, 2016.

  1. JayTee

    JayTee Active Member

    I am bringing this 1966 Riviera out of retirement that has a Rube Goldberg California smog equipment set up that must have been designed by a plumber. It could not have been a GM design. The Vin # says it was made in the Flint plant while the Fisher plate says it was assembled in the EUC plant. I suspect that the smog equippent was put on at the EUC plant before sending the vehicle to California. ,
    Anyway, I feel the car is an original car without the smog equipment since it was an add-on and I would like to remove this ugly mess and make it look like all the other Rivieras that left the Flint plant.
    By the way, I.know it ran for 3 years without the belt connected to the pump.
    The main reason I want remove this equipment is because the bracket that holds the pump is bolted onto the water thermostat housing so that you have to remove the air pump aand whole bracket (6 bolts) in order to change the thermostat (what a stupid design).
    So my questions : what goes in the exhaust ports when I remove the tubes? Is there anything else I need to change?
  2. wkillgs

    wkillgs Gold Level Contributor

    You can use set screws to plug the holes in the exhaust ports.
  3. SpecialWagon65

    SpecialWagon65 Ted Nagel

    Check out the threads on this 67 A I R system. I bought plugs from Year One and they were just pipe thread.
    this is some weirdo thread!

  4. Schurkey

    Schurkey Silver Level contributor

    Only if you want a failure.

    Not "weirdo" at all. Standard issue inverted flare fitting. Brass inverted flare plugs are available at every auto parts store in America, in the Edelmann display. The sealing surface is the tapered end, NOT THE THREADS. They'll probably stock two or three of them, you'll probably need eight.

    I thought Arizona was anal-retentive about OEM emissions equipment.
  5. John Codman

    John Codman Platinum Level Contributor

    I have seen people just braze up the hole in the stock manifold fittings and reinstall them.
  6. 8ad-f85

    8ad-f85 Well-Known Member

    I've seen people braze the broken off steel fittings and leave them.
    Why braze up an iron manifold when a simple pipe plug will do the trick?
  7. lemmy-67

    lemmy-67 Gold Level Contributor

    Since when does the AIR system connect to the transmission cooler lines?

    I have the stock AIR system intact on my 67, and the check valve pipes to the heads look nothing like that.
  8. wkillgs

    wkillgs Gold Level Contributor

    Disagree... a simple bolt or set screw should work fine and not fail. Just use a thread sealer such as hi-temp silicone and it should seal.
    1/2"-13 straight thread.

    I took a closer look at my '66 AIR heads and there is not an inverted flare machined into the bottom of the threaded hole. There is a slight lip there for a tube to seat against, but no inverted flare.
    The threads are not fully cut to that lip.
    A set screw would reach the ends of the threads and should seal, via the threads.
    A brake line plug would work the same way... the threads would bottom out. A brass plug would have the advantage of being softer.

    The air lines go into the cylinder heads, not the exhaust manifolds. Brazing the holes closed would risk damaging the heads!
  9. Wildcat GS

    Wildcat GS Wildcat GS

    These have a tendency for the nuts to break off as they are very thin gauge. What one is left with is an open tube (assuming one used a cut-off tool to cut off the tubes first to get a socket over the nut) with the threaded part of the nut remaining behind in the exhaust manifold or the head...not good! The simple solution is to cut off the tube close to the nut, flatten the tube and braze the flattened end closed.
    Tom Mooney
  10. Schurkey

    Schurkey Silver Level contributor

    Looking at the previously-posted photo, what you have is EXACTLY what I'd expect if those holes started out machined for inverted-flare fittings, then corroded a bit over the decades of use. Especially the part about the threads not going all the way to the lip--look at the photo of the inverted-flare nuts!
  11. 8ad-f85

    8ad-f85 Well-Known Member

    Thanks for the clarification!
    I've dealt with literally tens of thousands of heads and try not to get into specifics of basic repair work...
    My point was NOT to braze up iron when a really simple solution the mods to the steel parts.
  12. telriv

    telriv Well-Known Member

    I installed regular bolts. I believe they were 7/16ths. course thread. Tightened them up then ground them off flush.
  13. JayTee

    JayTee Active Member

    Great discussion on this subject guys! Lets see how its going.

    Walt says to use set screws in the exhaust ports which makes sense to me.
    Schurkey thinks the use of set screws will end up with my being in trouble but doesent say why he thinks this.
    Specialwagon65 showed us a picture of the pipes that were inhis 67 that looked like mine confirming that a plumber must have designed this system.
    Schurskey in formed us that these are not plumbing fittings but are inverted flare fitting and inverted flare PLUGS are available at auto parts stores.
    By the way Schurskey, Arizonia doesn't care about emmisions if your car is more than 29 years old or if you do not drive into Phoenix.
    John Goodman & 8ad-F85 say they have seen people just braze the end of the pipe to seal it off.
    To me that would lookalittle ugly. 8Ad-F85 says why not just use a pipe plug? Now that makes sense to me.

    Len asks a question about the transmission line connected to the A..I. R system. where did this come from?
    Len I have a question for you is the air pump bracket in your car bolted onto the water thermostat housing like mine was?
    I like Tom's approach its simple enough except for grinding off the heads of the bolt (I don't have a machine shop) I could cut the bolts short & leave the heads flush with the block at least it would look better than it does now and easer to get at the plugs.

    Question: Did Buick cast a special block for access to these exhaust ports?
    Another question: since this was the last year for the 425 does anyone know the date and serial number of the last engine?
  14. wkillgs

    wkillgs Gold Level Contributor

    Here's a pic of the set screw/plugs I put in my '66 401. They are 1/2"-13 thread, 1/2" long. It's a straight thread, not a tapered pipe thread!
    Find ones that don't have serrations on the end, just a plain flat end.
    Easy fix and it doesn't look too bad. You can fill in the allen wrench hole with silicon if you don't like the look of the recess.

    I checked the thread size twice. Trust me!:grin:

    DSCF1509 (Copy).jpg
  15. telriv

    telriv Well-Known Member

    Sorry, was wrong about the size. I checked & Walt is correct in that they are 1/2". Cut them off with a hacksaw & finish with a grinding wheel on a Dremel tool.
  16. SpecialWagon65

    SpecialWagon65 Ted Nagel

    I am inclined to trust you. I bought a 66 Ford that has had the A I R removed...previous owner used 1/2" bolts for plugs.
    Ugly, but functional.
  17. Schurkey

    Schurkey Silver Level contributor

    Set screws may have the correct thread size, but the wrong sealing method. They aren't designed to seal a hole, they're designed to secure something from vibrating loose.

    You need inverted flare fittings if you're interested in not screwing-up the sealing surface of the casting.

    But what the hell. Ram in some easy-to-source set screws or bolts or pipe plugs like everyone else. If they leak, they aren't tight enough. Who cares about fifty year old castings that will be difficult to replace? Cutting, folding, and brazing the existing tubes at least has the advantage of being the correct fit in the casting. The castings may/may not have existing damage in those holes anyway via heat cycling and corrosive exhaust eroding the iron. You've been told what the correct product is, and you've been told how to cheat when not using the correct product. Take your pick.

    "I" would have left the AIR system in place, especially if it wasn't full of rust and had the potential to be made functional again. But that's me. A thousand years ago, my SS396 got pipe plugs in the exhaust manifolds. I had no idea, and a bunch of high-school friends who thought pipe plugs would make the engine run better.

    No, because AIR access to the exhaust ports is from the cylinder heads, not the block. The cylinder heads have bosses cast-in to make machining of the AIR ports practical, therefore the head castings are "special". Wild Guess: Not all castings had the bosses, not all castings with the bosses actually got machined for the AIR pipes.
  18. wkillgs

    wkillgs Gold Level Contributor

    Understand your point..... a simple plug will leave the original seat exposed, making it vulnerable to damage from corrosion.

    However, the SAE inverted flare fittings you mention are 1/2"-20 thread, we need 1/2"-13.
    Another issue is that the A.I.R. ports don't have an inverted flare seat.... there's just a small lip for the tube to seat against. (This is looking at the two sets of '66 A.I.R. heads I have here).

    Perhaps there are other fittings avail with the proper thread and an extended nose that will seal against the original seat.
    I'm thinking a brass set screw or plug with a flat end and a few threads ground off the end would allow it to fully seal against the original seat.
    McMaster-Carr is likely to be a source for something that will work.

    Drop in a 1/4" long piece of round stock to seat against the original seat and screw the set screw in on top of it.
  19. Lucy Fair

    Lucy Fair Nailheadlova

    I know it's kind of old thread but i have finally found pix of what i believe is an NOS A.I.R. plug for 66 nailheads.
    Like they say picture is worth thousand words.


    Attached Files:

  20. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    how often are you messing with the thermostat? doesn't seem worth it. while the air pump isn't real attractive under the hood, pumping fresh air into the exhaust isn't hurting performance a bit. it's a system that is very misunderstood.

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