exhaust system

[mpbohio]

I'm replacing a 21 hp B&S engine with a 20 hp model on my Husky lawn tractor. The exhaust pipe to the old muffler is a little wider than the port off the cylinder of the new engine. Do I have to worry about about exhaust entering the larger system? Is back pressure a consideration? The exhaust system is in good shape and I'd like to use it. Otherwise a new muffler to match the engine is $120 and it won't sit in the proper place (higher, in front of the air cleaner). Thanks.

 

[RN]

This is where you learn how to cut beer cans, wrap and hose clamp pipes. A inner sleeve screwed into engine exhaust port and a clamp to old muffler pipe cut with a split should work. Many of the Briggs engine were inside threaded for standard pipe size as well as outside flanged pipe bolts or studs. Also- auto parts store exhaust section probably has reducer/expander/coupler bushing pipe pieces that may help fit. RN

 

[mpbohio]

Thanks for the info. The exhaust pipe has a flanged end, not threaded. With a custom cut gasket and a little filing of the mounting hole I can get it to fit to the new engine. Should I put anything in the exhaust pipe to correct the minor mismatch in diameters? Should the exhaust system provide sufficient back pressure?

Thanks again.

 

[Anonymous-0]

If the flange bolts up, just use a new gasket and don't worry about a minor difference in diameter of port and pipe.

 

[Trailer Trash Tractors]

I'd consider buying a second manifold, than cutting both to create a dual exhaust system.
You could terminate pipe with a 1" male thread Copper Spud, and screw a Kohler ' Pepper Pot ' muffler on each side . Would be cheaper in long run, replacement mufflers screw right on.

Some sub - standard size cars have exhaust pipes to match, could local auto parts store sell suitable tubing ? B + S makes a very tough muffler clamp for the vanguard twin.

Good luck .

 

[mpbohio]

Thanks much. Hopefully I'll finish it this weekend.