LSA or Duration to fine tune glasspacks??

The sound is not in the cam. Well not in the sense of the tones. The timing of the exhaust opening certainly plays a role, if you are looking for the energy, and the late closing intake allows some compression back into the intake, where it messes up the AFR, and makes the common lope as the ignition tries to keep up. But building an engine or camming an engine for the sound out the tailpipe is kindof strange,to say the least. As to tonality,you will get the biggest results with tip shapes and size of tailpipes. You cannot of course duplicate the lope. But honestly cams under 225* in a hiC engine have very little lope at normal idle speeds.From there to 235ish you still have to idle them down pretty far to hear it.Really the cam needs to be up around 240/250 before it becomes noticeable at a normal idle speed, of 750ish. But by this time the cam is fast taking you out of the realm of streetability. Do you really want a race-cam in your streeter? I bin-der/done-dat, and it was fun while it lasted(one summer), but I'll probably never go back there.Naw a nice streeter has a 230ish or smaller cam, 360 plus cubes, and some hi-flo heads.With a well matched Scr, this makes very little lope at a normal 750ish rpm. You need that 750ish rpm to keep all the fluids pumping, and possibly to keep the brake booster ready to go.And of course with an auto, the TC will drag it down around a hunert rpm. So, if you really want the lope, get yourself a 292/292/108, or something along those lines (heaven forbid, a Thumper), idle it down to 650,and let the tuning begin.But when you find out the power doesn't start til up around 5000 rpm, and the beast don't like to pull below 2500 to 3000, well hey, you got yourself a nice lope, right? Did I mention that cam burns a lotta gas? Well it doesn't actually burn all of it.heehee.Some of it burns in the pipes on the way to the mufflers, and if you do it just right, you can blow one clean off! And some of it stays in the mufflers when you shut it off. There it mixes with condensation,forms acids and soon you will have that ugly 4-banger sound, as the acids eat holes in your holey glass-pacs.lol. Ok now I'm just being mean,sorry.
Yeah so, to quote another guy,good luck with that.

Personally I like a nice thoop-thoop-thoop-thoop-thoop. And I know exactly how to get it; Take one 1969 340 short block, and throw away the cam. Stick a teener cam in it dot-to-dot,lol. Bolt on a set of open chamber teener heads, a CI intake with a TQ.Add a set of fenderwell headers,two to 2.25 inch very straight pipes to a pair of cherry bomb shorties.Add very straight under the axle 1.875 pipes out to the rear bumper. Take an 18 inch length of cardboard, and roll it up until it fills the end of the pipe. Drill a hole vertically up thru both sides and drop a 3inch nail down thru it so the cardboard doesn't go AWOL. Repeat on other side.Start her up and crank the idle down to 500; There you have it; thoop-thoop-thoop-thoop-th
I can almost guarantee that when you hear it you will nearly die laughing.
Now put you some 340 springs on those teener heads and some 3.55s out back.Pop the pins and let her fly. In a sub-3000 pounder like a 65 long-roof Valiant, the laughing will stop, as your brain tries to figure out what just happened. Then you will begin laughing all over again.
thoop-thoop-thoo
This cannot be, can it?
Hey that was me in 1975. I still remember it fondly, almost like it was 40 years ago....