1985 big block 454, California emissions, exhaust manifold tubes, any plugs out there - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**57NAPCO** · 01-12-2017, 07:28 PM

The previous owner cut and pinched the tubes off, they leak

I'd like to just plug all 8 of em with a plug or bolt, anyone know where to find such a thing? Seems to be an odd ball size...napa has no such thing and that's my only resource in our small town.
Thanks!

100%Chevy · 01-12-2017, 07:49 PM

I have the same engine.
Someone before me removed the tubes,kept the nuts and put pennies in the holes!
It's still working!
And,I ain't taking them out till it leaks!

Mike.

**57NAPCO** · 01-12-2017, 07:52 PM

burban nate · 01-12-2017, 08:51 PM

Quote:

Originally Posted by 100%Chevy

I have the same engine.
Someone before me removed the tubes,kept the nuts and put pennies in the holes!
It's still working!
And,I ain't taking them out till it leaks!

Mike.

If they are still solid copper pennies it'll probably last forever but if they are the copper plated zinc pennies it may not last long. Not sure what year the gov't went to the zinc pennies tho.

Nate

EDIT: just looked it up, all US pennies after 1982 are copper plated zinc.

tinydb84 · 01-13-2017, 01:56 PM

I thought they were NPT but could be wrong. I would take the nuts out and weld the holes shut.

raceman6135 · 01-13-2017, 05:37 PM

They're not an NPT thread because it is not the threads that do the sealing; it is the 45-degree flare that does the sealing. Regardless, when I removed my A.I.R. (Air Injection Reactor) tubes, I used BRASS pipe plugs (common hex head that you can find at auto parts stores, hardware stores, plumbing supply places, etc.). I believe mine used 1/4 inch NPT.

Example:

The reason I used brass plugs is that they will thread in a turn or two, and when you put a socket on them and tighten them down another turn or so, the soft brass will deform and do a good job of plugging the hole in the cast iron manifold, and will not leak.

NOTE: you will have to completely remove the existing leaking tube and tube nut for this to work. If you can't remove the remnants from the previous owner's "modification," I'm not sure what will work, other than maybe welding/brazing the ends of the tubes better than what the other guy did.

01-12-2017, 07:28 PM	#1
57NAPCO F’B’D guy Join Date: Feb 2004 Location: Texas/Maine Posts: 2,234	1985 big block 454, California emissions, exhaust manifold tubes, any plugs out there The previous owner cut and pinched the tubes off, they leak I'd like to just plug all 8 of em with a plug or bolt, anyone know where to find such a thing? Seems to be an odd ball size...napa has no such thing and that's my only resource in our small town. Thanks!

01-12-2017, 07:49 PM	#2
100%Chevy Registered User Join Date: Jun 2008 Location: Moss Point,Ms. Posts: 1,439	Re: 1985 big block 454, California emissions, exhaust manifold tubes, any plugs out t I have the same engine. Someone before me removed the tubes,kept the nuts and put pennies in the holes! It's still working! And,I ain't taking them out till it leaks! Mike.

01-12-2017, 07:52 PM	#3
57NAPCO F’B’D guy Join Date: Feb 2004 Location: Texas/Maine Posts: 2,234	Re: 1985 big block 454, California emissions, exhaust manifold tubes, any plugs out t

01-13-2017, 01:56 PM	#5
tinydb84 Registered User Join Date: Jul 2009 Location: San Jose Ca Posts: 2,871	Re: 1985 big block 454, California emissions, exhaust manifold tubes, any plugs out t I thought they were NPT but could be wrong. I would take the nuts out and weld the holes shut. __________________ David Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991 My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985 Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557 Instagram: myfabguy

01-13-2017, 05:37 PM	#6
raceman6135 Dino burner Join Date: Nov 2002 Location: Calgary, Alberta, Canada Posts: 602	Re: 1985 big block 454, California emissions, exhaust manifold tubes, any plugs out t They're not an NPT thread because it is not the threads that do the sealing; it is the 45-degree flare that does the sealing. Regardless, when I removed my A.I.R. (Air Injection Reactor) tubes, I used BRASS pipe plugs (common hex head that you can find at auto parts stores, hardware stores, plumbing supply places, etc.). I believe mine used 1/4 inch NPT. Example: The reason I used brass plugs is that they will thread in a turn or two, and when you put a socket on them and tighten them down another turn or so, the soft brass will deform and do a good job of plugging the hole in the cast iron manifold, and will not leak. NOTE: you will have to completely remove the existing leaking tube and tube nut for this to work. If you can't remove the remnants from the previous owner's "modification," I'm not sure what will work, other than maybe welding/brazing the ends of the tubes better than what the other guy did.



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