Author Topic: 1968 smog manifolds  (Read 2488 times)

fireZ

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1968 smog manifolds
« on: October 21, 2010, 10:48:52 PM »
Anyone know the thread size for a smog fitting on a 68 Z. I need to run a tap through to clean up my thread to put smog tubes in.
1968 Z28 LA Built
LIC # RPO Z28

Boston14

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Re: 1968 smog manifolds
« Reply #1 on: October 21, 2010, 11:04:20 PM »
Check this post;     http://www.camaros.org/forum/index.php?topic=7067.0   



boston14
boston14

1969 SS/RS 350 Convertible
Dover White with Black Top and D90 stripe, Red Standard Interior

fireZ

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Re: 1968 smog manifolds
« Reply #2 on: October 21, 2010, 11:07:21 PM »
I can not seem to pull it up on the site
1968 Z28 LA Built
LIC # RPO Z28

Boston14

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Re: 1968 smog manifolds
« Reply #3 on: October 21, 2010, 11:14:38 PM »
I didn't know how to insert it as a link ....... just copy it and paste it in your browser and that will take you there.
boston14

1969 SS/RS 350 Convertible
Dover White with Black Top and D90 stripe, Red Standard Interior

Gramps69Z

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Re: 1968 smog manifolds
« Reply #4 on: October 22, 2010, 12:18:44 AM »
Captain John Wykoff
Destin Fire     5 months  to go

I'm sick and tired of mismanagement and disappointment. 
I'm a COWBOYS fan.

acelr8

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Re: 1968 smog manifolds
« Reply #5 on: October 22, 2010, 01:01:56 AM »
1/4 Straght pipe not taper pipe is correct.Jeff

169INDY

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Re: 1968 smog manifolds
« Reply #6 on: October 27, 2010, 04:29:28 AM »
I just went thru something similar.
One of the A.I.R Trees rotted out from the inside and required replacement.
Twisted off two of the 4 nuts and had to machine out the thread (Nut) while not intruding i.e. damaging the manifold.
I used a series of drill bits up to the correct tap size and pulled the 'treads' of the nut out of the manifold holes,,,
then purchased (appx 40$ ouch) a 1/4-18 NPSF 4FLT STR D/S Pipe tap from Fastenal (pn 16356 Brand Greenfield Tap & Die) and chased my manifold thread for a clean fit on the new tube nuts.

P.S. also machined some custom hidden plugs that seat below the tubes as my pump is de-vaned and need to seal exhaust gases from the check vlv etc.

Jim
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS

JohnZ

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Re: 1968 smog manifolds
« Reply #7 on: October 27, 2010, 02:41:34 PM »
P.S. also machined some custom hidden plugs that seat below the tubes as my pump is de-vaned and need to seal exhaust gases from the check vlv etc.

Jim

You can also use #10 x 1/2" flat-head machine screws in the holes in the exhaust manifolds (after knocking out the stainless tubes) instead of having plugs custom-made; the air manifold tube nuts then tighten down to the same dimension as if the tubes were still installed.
'69 Z/28
Fathom Green
CRG

169INDY

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Re: 1968 smog manifolds
« Reply #8 on: October 29, 2010, 01:44:24 AM »


You can also use #10 x 1/2" flat-head machine screws in the holes in the exhaust manifolds (after knocking out the stainless tubes) instead of having plugs custom-made; the air manifold tube nuts then tighten down to the same dimension as if the tubes were still installed.
[/quote]

Ya, I have even heard of folks suggesting (I would not) installing roofing nails to block the passage. Not very durable in my opinion.

I removed the tube, extensions. Machined (On a Lathe I have) a tight tolerance -plug- with shaping to really seal it up good. The "head" height was calculated to acquire the same standoff distance on the smog air manifold tree tube nuts. It was fun making CHIPS! The plugs do not intrude into the exhaust manifold chamber area at all.
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS

JohnZ

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Re: 1968 smog manifolds
« Reply #9 on: October 29, 2010, 04:35:51 PM »
Ya, I have even heard of folks suggesting (I would not) installing roofing nails to block the passage. Not very durable in my opinion.

I've done lots of them using stainless steel machine screws - they'll last forever, and won't corrode in place.
'69 Z/28
Fathom Green
CRG

169INDY

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Re: 1968 smog manifolds
« Reply #10 on: March 07, 2011, 04:09:55 AM »
Pic post: Pic of smog plug fabrication.

Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS

rszmjt

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Re: 1968 smog manifolds
« Reply #11 on: March 07, 2011, 04:23:22 AM »
3/16 blind trailer rivits inserted into the smog rails and rivited. They never move and seal up.