[B20BbenN]

First, the INLET of the TB is on the filter side....
If you check some honda TB size chart, the TypeR is 62mm(outlet).
Honda TB are taper: I have a prelude TB and the inlet is 62mm and the outlet is 60mm.

What do you really want to know?
-The inside diameter of the inlet side or the outside diameter of the inlet side?

 

[B20BbenN]

I dont know for sure but the I.D. should be between 64-65 mm assuming that my prelude tb have a 2mm taper....

 

[B20BbenN]

Mouhahaha you ask the Q but you already know the answer !!!?!?!?! lol
There is a reason why honda put a taper on their TB.....it is like a velocity stack on your intake system...

The ITR TB is a PERFECT match with your edelbrock intake!!!!

Install your ITR TB on your edelbrock intake, open the butterfly and put your finger in to check if the transition between the TB and the IM is smooth.....I have an edelbrock IM, but when I mesure the inlet, I only get 61.xx mm....that's why I pick a 60mm tb!
Prelude tb cost<itr tb!