yamahondarider

Hey guys, I've got a 1969 Cutlass S with the stock 350 2 barrel, single exhaust. What diameter is the exhaust pipe that runs under the car back to the axle? I threw a caliper on it and it read 2.3 inches but the teeth on the caliper weren't really wide enough to get an accurate measurement (plus I was trying to do this 1 handed reaching under the car . I need to pick up a muffler for the car. What size muffler should I grab for it to slip right on the stock exhaust pipe and clamp down?

MDchanic

My memory says 2¼".

- Eric

yamahondarider

So on the autozone website that should be listed as 2.25 correct? Its been a while since high school math

MDchanic

Yes....

... and that's 4th grade math. (I remember when my kid did it)

yamahondarider

Things being listen on as 1/16ths of an inch confuses me when we're talking fractions lol. This is why I don't build chassis or houses

MDchanic

Ha. You sound like one of them thar Yooropeeans. They can't handle fractions either.

You'll do fine as long as you use a micrometer instead of a yardstick.

- Eric

yamahondarider

Fractions suck. Ironically I'm an ace at algebra. I suck at geometry though.

I just need to quite this damn car down. The straight pipe sounds cool around the block but I have a feeling it'll get old after a while.

MDchanic

That's what it is, then. I'm great at fractions because somewhere in the back of my mind, I see them as geometric figures.

Two different kinds of logical perception.

I remember in high school, I observed that lots of people were good at either chemistry or physics, but almost nobody was good at both - same reason.

- Eric

yamahondarider

Yup, thats what I noticed and was told about geometry and algebra. Same situation. I'll have to get good at geometry whenever I build a back-half'd car though. Until now I just need to measure pipe diameter

Called Advance Auto, they have 3 glass packs in stock in the inlet/outlet diameter I need. 25, 27, and 31 inches total length. I've got some measuring to do under the car. Wish me luck

jcdynamic88

if you are running a stock tail pipe the muffler outlet should be 2 in

yamahondarider

I'm not measuring at the tail pipe though, I'm measuring at the wider diameter pipe directly under the middle of the car before the axle, like where it gets close to the driveshaft under the floorboards. Its definitely bigger than 2 inches

jcdynamic88

i knew you were concerned with the inlet diameter but just thought you might want to know the outlet is smaller. if you get a muffler that is 2.25 in and out it probably will be too big for a stock tail pipe

yamahondarider

Ah okay. Yeah I'm not running any tail pipe it all rotted out. Factory original exhaust from 1969. I'm just jamming a glass pack over the cut-off pipe under the floor pan to quiet it down. I might put a turn down on it instead of having it scream at the differential, I'm not sure yet. I don't plan to run this engine for too much longer so I'm trying to spend as little as possible on exhaust work. Just want to drive the car this spring/summer/fall before I tear it apart next winter.

yamahondarider

If anyones curious the proper size for the pipe before it loops up over the axle is indeed 2.25. I threw on a glasspack, its a bit quieter now. Well spent $25. I do need to put a 90 on it and send a tail pipe out under the door in front of the rear tire to help with fumes when the windows are down but it isn't bad

BangScreech4-4-2

Well, judging by the sound of the car's general condition, you might want to avoid driving it with the windows UP. That carbon monoxide is nasty stuff.

yamahondarider

What are you trying to say about my car? . I don't see how the fact that after 40 years it needs a new muffler can give you a good idea of my car's general condition without any other background or pictures?

Its no show queen but it isn't junk. Its not like its got asbestos for insulation. Now my '76 280Z I had for a while, that car was VERY bad about exhaust fumes in the cabin. Compared to the 280Z the Cutlass smells like fresh daisies.

BangScreech4-4-2

Your description. Regardless, I bet it'll be real nice after next winter.

yamahondarider

Only thing I described about the car is the exhaust. I said the tail pipe section rotted out so I wouldn't be using that just dumping before the axle. Only reason I'm not going all out on true duals is because the 350 is being pulled in favor of an LS. I just want to put some miles on it before then without being too deaf to hear the new engine when its in lol