Sideways Posted September 5, 2011 Share Posted September 5, 2011 Alright fellow gurus- I am once again calling on your awesomeness here. What is the thread size of the fittings for the air injection system on the exhaust manifold? The PO removed the system and plugged it himself- But weve a sneaking suspicion he used the wrong size threads as 3 now have fallen out. I know welding would be the best way to go, but the motor is going soon so i dont want to spend the money on welding it, just want to get a cheapo' fix that will last for now so I can drive the vehicle without going completely deaf. Thanks again everyone! Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted September 5, 2011 Share Posted September 5, 2011 I believe i used a 1/4" npt pipe thread purchased from my local hardware store. Quote Link to comment Share on other sites More sharing options...
Leon Posted September 5, 2011 Share Posted September 5, 2011 The threads are BSPT (or BSPP?). BSPT would be tapered and BSPP is parallel threads, you should be able to tell by looking at or measuring the holes. NPT will fit but not seal as well due to different thread design, not sure how dramatic the difference would be with exhaust fumes though. You can use McMasterCarr to get the plugs as well. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 7, 2011 Share Posted September 7, 2011 They are an ISO straight fitting, there is no taper. The only way NPT fits is you either jam it in there till it seizes, or you retap it. There are straight screws out there that will thread in and plug it satisfactorily. Allen Hex Head setscrews, actually. A centerpunch will stake them in place to prevent backing out once installed. Quote Link to comment Share on other sites More sharing options...
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