Freestyle Tap size for factory pipe manifold

[swapmeet]

I tried searching for this a couple different ways with no luck.

What size pipe thread tap do I need to drill the other side of my factory pipe manifold?
Mine is only tapped on one side and I want to get it done before I install my engine.

Thanks

 

[Texan33]

Can you be more specific? What other side of your factory pipe manifold? Are you talking about the holes where the bolt goes in that secured the headpipe to the manifold?

 

[davidy]

If you are talking about the cooling line fitting for dual cooling then you need to get a 3/8 or 1/4 barbed fitting and get a tapered NPT tap it has to be NPT tap to match the threads on the barbed fitting a normal taps wont work

 

[motobehrens]

tap: 1/8-27 pipe
bit: 21/64

 

[swapmeet]

^^^ Correct. NTP tap... buddy just texted me the answer. Thanks ya'll... hopefully someone else finds this if they're looking.