361 muffler mod

[treefrog359]

i know, i know, i have done searches on this topic. but no where is a physical number in opening size. all i seen was drill three holes and that was it. i have one 7/16 opening ( stock ). how much more area can i add to this. i have done the math at 80% and it comes to .25 square inches. dose that sound right? what about any other modifications to the 361.
just looking for a little help be for i jump in.

 

[Lakeside53]

Can't believe the AS muffler mod crowd hasn't jumped in here to help you! Maybe they are busy with the Dean thread...

Why not just try it at 80%? If you add a screen, make it larger in proportion to the blockage ration of the screen. You can always make the hole larger... Buy a "Uni-bit" if you are going to drill in the front. These make drilling nice holes in thin sheet metal a breeze.

Out here a few of the guys just take out the existing screen and drill (carefully, at and angle, with the muffler OFF the SAW so you don't get any junk inside) the existing hole to about 9/16 inch, then put back in the original screen. Hmmm, that's very close to .25 sq inches. Given the angle, it's actually quite bit over .25 inches, but with the screen back in it's closer.