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#1 |
Registered User
Join Date: Jan 2004
Location: Whitehorse YK Canada
Posts: 2,651
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Replacement Exhaust manifold plug size
Truck is a 1968, C20 with the factory 396. Left exhaust manifold cracked so I bought a replacement and installed it. The new manifold has the AIR holes and the large threaded home near the exit point. I have straight pipe plugs in the 4 AIR holes, and that works great.
Any idea what size and thread the hole is near the exhaust exit? Posted via Mobile Device |
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#2 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,431
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Re: Replacement Exhaust manifold plug size
Do you have a picture? I'm not familiar with anything but the 4 A.I.R. ports and the exhaust port. Maybe it's for an Oxygen sensor?
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#3 | |
Registered User
Join Date: Jan 2004
Location: Whitehorse YK Canada
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Quote:
Looking for the plug that is pictured on the left side of the photo. Posted via Mobile Device |
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#4 |
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#5 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,549
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Re: Replacement Exhaust manifold plug size
Actually for the smaller tube holes, the size is 5/16'' tubing plug. If you tighten the pipe plugs too much you can crack the manifold. Yeah, big hole is for an O2 sensor. Size as stated---should have had a plug in the box when you purchased it, just like mine did
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#6 | |
Registered User
Join Date: Jan 2004
Location: Whitehorse YK Canada
Posts: 2,651
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Quote:
I didn’t use tapered pipe thread I used straight pipe thread. So it wouldn’t tight and has to use something to lock the threads in place. Posted via Mobile Device |
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#7 |
Who Changed This?
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Location: Simi Valley, CA
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Re: Replacement Exhaust manifold plug size
There are 5/16" plugs that have the same thread as a tubing B-nut, and have the inverted flare on the end to match what is machined into the exhaust manifold. Straight pipe plugs will probably work fine, though I haven't ever done it that way. Looks like you have a universal manifold that fits a ton of years.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#8 | |
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Location: Falls City, Nebraska "100 Miles From Nowhere"
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Re: Replacement Exhaust manifold plug size
Quote:
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Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" ![]() "Be American, Buy American" ![]() |
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#9 |
Registered User
Join Date: Jan 2004
Location: Whitehorse YK Canada
Posts: 2,651
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Re: Replacement Exhaust manifold plug size
Found a oxygen sensor plug yesterday and it fits great. One quiet ride again.......
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Blaine 59 GMC 9314 a.k.a. Whoopee 68 C20 50th Anniversary a.k.a. The Rat http://www.flickr.com/photos/northerngmc/ http://www.members.tripod.com/P-wee/index_032.htm 1.61803 is one H of a lot better than 3.14159, no really it is! |
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#10 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
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Re: Replacement Exhaust manifold plug size
Excellent!
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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