Is exhaust pipe size ID or OD?

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halfafish

Damn those rabbits, and their holes!
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Howdy Folks! It's time to display my ignorance once again.

The exhaust on my 69 Dart 340 is all wonky. Whoever put it together got the angles all wrong, and now the turn downs which are just in front of the axle are pointed right at the wheel/shock/brakes which can't be good for any of them. It also is hanging down quite a bit lower than necessary, reducing ground clearance.

I need to get new header collectors, cut the old pipe off, and re-weld it correctly. When ordering the collector/reducer, is the size of the exhaust pipe determined by the ID or OD?
 
Pipe is always ID. Tube is measured OD. So theoretically a 1.00 tube will fit inside a 1.00 pipe...and why a 3/8 pipe fitting is huge.
 
Exhaust "pipe" is not water pipe It is sold OD

OT !!!! This gets complicated sometimes, eg HVAC/R vs plumbers. Copper water "piping" which except for wall thickness, is "called out" in nominal ID. The refrigeration tubing (same stuff sometimes different wall thickness, uses same fittings dimensions) is normally called out in "true" OD

I've often thought water pipe was completely stupid. You have sked 40 which is thinner walled than ske 80, but it all must be same dimensions OD.
 
People call it pipe but its tube and it is measured by the O.D. with the exception of expanded slip joints, it will say its I.D. so you know it will slip over the corresponding tube of the same size.

Summit and Jegs sell a decent mostly bolt on kit.
 
Exactly. It's measured OD. All you have to do is put a dial caliper on it. You'll see.
 
And mufflers are usually sold with connections that will slip over. In other words, inner diameter.
 
And mufflers are usually sold with connections that will slip over. In other words, inner diameter.
Exactly. Id and OD. For 2 pipes to fit together, one has to be OD and the other is ID the same size.
 
do these work for you?
they have been collecting dust in my garage for long enough


pay shipping and they are yours

(OD is 2.5, so the but up to the rest of the exhaust, or slip into the flare)

20200330_180929.jpg


20200330_180936.jpg
 
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