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Discussion Starter #1
Having trouble and need help.

I have new thermactor tubes (smog trees) and new nut/ferrules. Prior to trying to install, I ran a tap to clean the theads in the head and wire brushed the holes. I placed the ferrules over the tubes, as far as they would go. The tips of the tubes stop short of the tip of the cone of the ferrule and will not go on any further. When I got to tighten the nuts, the threads seem to bottom out in the head before securing the tubes. When I back everything out, the some of the cones are still with the threaded nut and some of the cones break off and remain in the head, but none of teh cones break off and remain on the tubes. What am I doing wrong? Are the thermactor tubes supposed to extend through the ferrule cones before screwing in? If so, without modification to the tube or cones, it does not seem possible. I have no experience with the tubes and not sure what I am doing wrong. Thanks.
 

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I will try an answer, I think you are missing a part, if this is to be a working smog set-up, you need a piece that is a tube with a flair on the end that goes in each hole, then the ferrule seats against this flair and creates a seal. As far as tapping the hole, I thought the hole was a taper fit like a pipe thread. It's been a while since I installed any
 

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Discussion Starter #3
Hmm. So in addition to the smog tree, with ferrule that slips on, you believe I might be missing something that inserts into the hole in the cylinder head, before I install the tree/ferrules? I am totally confused.
 

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There is nothing else than the tube, the ferrules and the nut. What I found when I installed the tubes in my heads was that in some of the holes the old ferrules were still there stuck in the head making it impossible to seat the ferrule correctly so in would fasten the tube. Have you checked that?
 

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i believe the thread in the head is straight pipe --NPS---if you use a std taper pipe tap---NPT--you will not clean the id threads clear to the bottom---i've even taken a NPS tap and machined a dimple on the end to clear the inverted flair male cone in the bottm of the hole---use carbide to modify the tap and lots of rpm
doctordesoto
 

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Discussion Starter #6
Thanks. I will find the NPS tap and see if that does it. I hope that is it, I want to get the tress on before installing the motor.
 
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