Quote:
Originally Posted by 51504bat
|
The 2G throttle bores are 1 7/16" while the Merc manifold has 1 3/8" throttle bores. To get the best performance, the Merc manifold should be bored out to the 2G size. I do this with a device called a "Rota-Broach" and bore the manifold all the way down. I have done both aluminum and cast iron manifolds, and the "Rota-Broach" cuts both easily. I have a guide I made out of a 1" block of aluminum that I bolt to the carb mounting surface. I then bolt the manifold to my drill press base at the correct angle and run the broach down. Because of the depth of the cutter, the cutter is self-guiding. It's not a difficult task. The "Rota-Broaches" are kind of expensive, but I could be convinced to rent mine out. Here's what they look like :