intake manifold plugs

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megavites

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As far as I can tell...plugs to block off extra intake holes are 3/4"-16.
Is that right?
 
They are pipe thread. I am not sure of the size, it is whatever pipe plug or pipe reducer threads in. No need to overtorque them, a little pipe dope is a good idea on the threads.
 
I just re-checked. The threads are 3/4-18 on new intake.
Pipe threads are NPT which is 14 threads per inch.
 
Any domestic intake that I have ever seen uses pipe thread for vacuum ports. Not to say your new intake couldnt have straight cut threads, if it does you would need an o ring, gasket etc. to seal it properly.
 
Yea..i'm used to pipe plugs but these measures out to 3/4-18.
Its an edelbrock performer manifold.
 
Use pipe plugs, i like brass ones, use hi temp thread sealer also
u should have some hi temp thread sealer around, need those for exhaust manifold bolts/studs that go into water passages
 
So.... pipe thread sizes are related to the pipe diameter that they are intended to be used with, not the hole diameter of the threads. What you have is a 3/8 18 pipe hole I believe. You should be able to see the taper in the threads if you look closely.
 
Vacuum fittings are 3/8" pipe thread...

Factory temp sensor is 1/4" pipe thread...
 
Just to avoid future confusion, a tapered pipe thread is not usually designated as 3/8-18. Just say it's 3/8 NPT, or even 3/8 pipe thread, and everybody will know what you're taking about. For reference, the biggest part of a 3/8 NPT is around .638", 1/4 NPT is around .502", 1/8 NPT is around .380". Here is a chart: National pipe thread - Wikipedia
 
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