Can someone tell me what these are for? I am rebuilding a pair of #3932461 exhaust manifolds for my 1979 L-82 and most of the parts I now have. But not these. They are not the AIR injection tubes; I have a nice set coming in. Apparently they are inserted into the manifold before the AIR injection tubes are screwed on. The Paragon listing shows them for 1966-78 applications. Did someone change in 1979? Thanks in advance for your help!
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
OK that link did not work. On the Paragon site they are part #1307K. -
Re: C3 AIR/Exhaust Manifold/Extension Tubes
There were tubes inserted in each hole (8) of the exhaust manifolds equipped for smog application. If you intend to disable the smog pump, just tap a lead sinker in each hole to block exhaust gases then bolt on your smog pipes for judging. I can't imagine the tubes changing between 78 and 79. have Paragon mic the ones they sell then mic the holes in your manifold before purchasing them, if your intent is to make the smog system functional. I used paragons tubes in one of my smog engines. I've also plugged holes in an engine that i disabled the smog pump good luck , mikeComment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
Mike:
What happens if you don't put these tubes into the manifold and hook up the smog system to be functional? Will something be damaged? Will the system not work as well? Could the exhaust manifold be damaged?
Thanks for your input.
Jeff SalzComment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
Mike,
My intention is to leave the AIR system functional. Will it work without those extension tubes?Comment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
That was my question of a few seconds ago . Those tubes are expensive!Comment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
As long as the holes are clean and not rusted shut so the air can pass through you do not have to insert the tube. I left mine out for years with no problem. They are stainless steel.Comment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
jeff and paul: the smog pump compresses fresh air and then injects it into the exhaust manifolds to ignite any unburned fuel arriving at the exhaust manifolds, ie the pump is injecting air only so if you leave out the stainless tubes from paragon, the only thing i can think of is the fresh air would n't be "centered" in the mass of unburnt gases so i'd suspect more enviornmental pollutants than you'd get with the tubes in place (to direct the fresh air( with O2) where it would do the most good at burning off the unspent gasoline). i don't think it would damage the manifold itself unless the point of combustion is nearer to the 8 holes drilled and tapped in the cast iron , in which case these areas of the manifold might be exposed to higher than normal temps. If $ is a considereation, one could probably make the stainless tubes themselves. get a stick of stainless pipe(after mivc'ing the I.D. of the 8 holes, then flare the ends with a flaring tool and fire the baby up. good luck. hope this dialogue wasn't too confusing.Comment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
Bob: are you sure they were stainless originally? only ever had one set of manifolds with the tubes still in place. got them from Noland about 15 years ago and he said he took them off a 66 Pass car chevy 396 K-19 orig car. seems to me the were carbon steel. had they been stainless , I'd have used them in my 67 L71 with K19 . however , its been about 12 - 15 years since i went thru that restoration. regards, mikeComment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
Thanks Bob. Paragon says "nickel material" and that may be SS.Comment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
Paul-----
The 1979 L-82 AIR extension tubes were different than earlier year models. Originally, these tubes were GM #14007363. However, those were discontinued several years ago and replaced by GM #12338013, which are still available from GM. Better news: these tubes list for just $2.38/each in contrast to the GM #3877484 used for most earlier small blocks which currently GM list for $8.90/each.In Appreciation of John HinckleyComment
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Re: C3 AIR/Exhaust Manifold/Extension Tubes
Mike
Thanks for the informative response. I intend to put my original AIR system back on this spring after the holes have been plugged up for 30 years. I was just afraid that by introducing the cold air into the exhaust manifold without the tubes (which I removed the last time the manifolds were off the car because they were all corroded), damage could occur. I think I will just hook it up without them.
Jeff Salz #13182Comment
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Re: Extension Tubes/ SS or?
Mike, I'm not sure if the tubes are stainless but they don't have a hint of rust. I have a set in my toolbox. Maybe they are steel or some type of metal that the heat doesn't hurt.
BobComment
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the manifold tubes
never leave the tubes in the manifolds if you remover the "spider" that feeds the manifold because the are a loose fit in the manifolds and i have seen the tubes hit on the back side of the valve heads. it you use "tubing fitting plugs" you will be ok because they will hold the tubes in place but just using tapered pipe plugs will let the tubes flip flop around. i have seen this happen and do to being lucky the only thing that happened was that the back side of the valve heads were clean from the tubes bouncing off them.Comment
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Re: Extension Tubes/ SS or?
if they are non magnetic they are some type of stainless as most but not all stainlees steels are non mag.Comment
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