I got a pretty nice deal on a used TB on Ebay and want to bore it out for my new project motor.
I can run a milling machine and do a lot of stuff for my car, so that is not going to be a problem.
My question merely relates to the limits as to how big you can go when boring out a TB, and more important, if the centers of the new oversize bores have to be offset in relation to the original 48 mm holes.


RG

 

52mm is the biggest I've seen a stock TB bored to. The bore should be centered to the original holes. I would recomend useing a fly cutter to do the boring with. The hard part will be making the new throttle blades.

Also, diassembly is a PITA. The throttle blades screws will not come out easy if at all.

 

ditto, i twisted the heads off of all 4 screws

 

Thanks for the tip.
I'll start with the disassembly. I had completely forgotten about that, If anyone has a suggestion as to how to remove the throttle blade screws please let me know. If that part goes smooth I will go ahead and bore it out to 52 mm.

 

Kinsler will sell you whatever size blades you need.

http://www.kinsler.com/Cat_31_Web_HT..._screen25.html

 

Heat the back of the screws with a small butane or propane torch. Has always worked for me. They seal the threads with loctite.

 

Thanks for the information and suggestions to everybody.
I'll post my results and findings afterwards.
Great info on the throttle blades....