Exhaust flow question

[Jeffcalgary]

Hi. I have a 75 911s running webber carbs. It has dual exhaust one for each heat exchanger. If i put my hand on the right side the exhaust flow feels steady pressure but the left side feels like there is a gap in the flow almost intermittent. Is this normal? The right pipe is connected to cyl 123 and the left pipe 456.

Other than this not feeling like there are any issues.

[Joe Bob]

There is likely more restriction on the path to the left outlet. If it bothers you, opening up the muffler and gutting it would free it up. More noise.....BUT a lot of people cap one side due to drone issues. It doesn't do anything except give the engine a bit more back pressure which some engines like. MFI mostly and other FI systems, not so much carbed motors.

Experiment and see what changes you get.

[Jeffcalgary]

Ok thanks...someone had said that one cylinder may not be fireing properly due to a worn cam shaft. Would this be a possibility?

[Joe Bob]

Pull the plug or injector wires on that side and see if there is a change in engine speed or sound.....or cap one side. The muffler is a mixing chamber and one side doe NOT exit one exhaust pipe.

[Jeffcalgary]

Ok thanks...this car has been fitted with two small mufflers one for each heat exchanger. Each side is separated.

[Joe Bob]

I missed that and reread your description.....either way a flat cam is rare. Running a can of Techron thru it is a good idea and or blowing out the jets in the carb on that side.

A stock banana muffler is a better idea than dual singles.....these motors like a little back pressure.