MSA muffler question

[AndysPlit]

I just had my garage install the MSA turbo muffler on my 78 280. Although it doesn't have the headers yet, and the catlyctic convertor is still on, the muffler sounds great.

However I will sometimes hear a vibrating sound....Almost like a slight rattle. I checked their work and everything seems fine. I called up my trusted mecahnic (great guy) and he told me that this was a normal sound for the MSA muffler due to its "tinny" nature. However, he said in time that sound should go away.

I'm not sure what is going on, but I sure hope that it does go away. I'm not sure if it is a resonance due to the construction of the muffler, or it IS rattling. Any thoughts?

[e_racer1999]

lemme guess, it's right around 2500 rpms?

[AndysPlit]

lemme guess, it's right around 2500 rpms?

Yeah, that's where it seems to start. But even in the lower RPM's I can still hear it....sometimes. What do you think? Thanks!

[beandip]

I think more like 1800 to 2500 RPM , although with a cat in place this should quiet down some of the resonance. I this is what 1999 and I suspect is the cause . Gary I must add that I have had a baffle come loose in a muffler in the past , but it was a definite rattle.

[e_racer1999]

basically, you need a resonator to get rid of that. a glass pack will do. what someone on here has done is put a piece of tape on the exhaust running the length from the header to about 3 feet back(?). run the car, and where the tape startes to scorch, install a resonator.

[AndysPlit]

OK. Is that before the catylctic convertor?

[e_racer1999]

i would assume after the cat.

i haven't done it myself, but i would think that right after the cat (within 6") would be ideal. just a guess. i don't remember who did the tape thing.... gary?

[beandip]

the tape on the exhaust pipe was some information I received from Dynomax. However I am not running a Cat and this may cloud the issue. One other thing that was mentioned , was when adding the glasspac . Use one that does NOT have the louvers in the pipe inside . They extend into the air flow and restrict. Thrush makes there glasspac with a perforated pipe that will not restrict flow. Either this one or a glasspac designed for a race application. They are made with a perforated pipe.

[e_racer1999]

thanks for that heads up, gary. i'm looking into a resonator for when i do MY MSA exhaust, and i would have grabbed just any old glasspack