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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Stewart G Griffin on July 13, 2021, 08:49:39 pm

Title: O2 sensor hole size and thread
Post by: Stewart G Griffin on July 13, 2021, 08:49:39 pm

Would anyone happen to know the O2 sensor hole size and thread type for 87 and up trucks?

This is is on the exhaust "Y" pipe nearest to the left exhaust manifold.

Title: Re: O2 sensor hole size and thread
Post by: dusterdude on July 14, 2021, 04:26:08 am

I believe its 18mm,not sure of pitch.its the the same size as an autolite spark plug for a 60's model ford.number 86,I think.

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Title: Re: O2 sensor hole size and thread
Post by: VileZambonie on July 14, 2021, 05:19:02 am

O2 bungholes are 18mm x 1.50

Title: Re: O2 sensor hole size and thread
Post by: Stewart G Griffin on July 17, 2021, 11:20:50 am

Good.  Thanks.

Title: Re: O2 sensor hole size and thread
Post by: Shifty on July 17, 2021, 12:16:10 pm

It's M18 x 1.5.

Title: Re: O2 sensor hole size and thread
Post by: Stewart G Griffin on July 17, 2021, 06:46:54 pm

Quote from: Shifty on July 17, 2021, 12:16:10 pm

It's M18 x 1.5.

Great.  It seems like the aftermarket A/F gauges also come  with 18mm X 1.5 sensors.

The reason i asked was because i was thinking about getting an air fuel ratio gauge in order to try to solve this carb problem.   And my Y pipe already has the factory hole and plug.

But i think i may try vacuum gauge first.

Title: Re: O2 sensor hole size and thread
Post by: Shifty on July 19, 2021, 09:29:00 am

A/F meter is a great tuning tool!

Title: Re: O2 sensor hole size and thread
Post by: VileZambonie on July 19, 2021, 06:52:51 pm

Using an O2 sensor to tune an engine is only worthwhile when the engine is 100% spot on running perfectly. Remember an oxygen sensor senses oxygen, not carbon monoxide, not CO2, not hydrocarbons etc. A cylinder misfire results in unburned fuel and air so your oxygen sensor will see high O2. Are you going to assume lean because of this? O@ sensor tuning is only for fine tuning a properly running engine. Using it to diag a drivability issue will send you down a rabbit hole. Since you are carbureted, don't bother. Fix your timing and then play with your carburetor.