Ok, I think this is one of those threads that is like opening Pandora’s
Box.
Tubing is normally dimensioned by its O.D. Where pipe is normally
dimensioned by it's I.D. or a nominal dimension. So, is "Exhaust Pipe"
actually pipe or is it tubing? There seems to be some confusion by what
I’ve seen on the internet.
The resto - pac’s from GM give the exhaust pipe O.D. as 2" for
all of the six cylinder engines. The tail pipe is specified as having
an I.D. of 13/16” which would give it an O.D. of approximately 15/16”.
.
I bought a new Greenlee 880 bender when I got out of the service
about 1968, thinking I would get into building dragster chassis. Well
that dint pan out but I have used it for other things over the years
such as axles and suspension parts for midget race cars. To bend
the radius rods and nurf bars and front axle kickup I added
tubing die sets to the box of goodies. I bout choked this past
summer when I priced a 2" "tubing die set". After that I gave
up the idea of bending my own pipes.
The problem I see with using a conduct bender is, that they are
sized for nominal dimensions. The 2" segment for the 880 is
sized for rigid having an actual diameter of 2 3/8" and that would
definitely flatten 2" "tubing". The 1 ½ " segment is sized for an
actual 1 29/32", now that would just make a mess of 2” OD. tubing.
The 1 ½ " shoe would probably work pretty good on a 1 7/8" O.D.
tube and I’m sure you could get away with using 1 7/8” tube for the
tail pipes.
Obviously a smaller cross section for the tail pipe only seems logical
because the gasses have cooled by the time they go thru muffler and
the volume would be less.
The bends for the original exhaust pipe are not that complicated, it’s
just one large radius sweeping bend (read step bend) and a couple
of very shallow angle (single digit) offsets. And those for the tail pipe
could be made using 1 7/8” O.D. tubing with the 1 ½” conduct shoes.
If any one of you electricians do bend up some 2" "tubing" for
an exhaust pipe or some 1 7/8” with your conduct bender,
please post some pictures.
Harbor Freight sells pipe expanders for about fifteen bucks:
http://www.harborfreight.com/tail-pipe-expander-69548.html And now, I'm out of wind and heading for my noon nap.
Denny Graham
Sandwich, IL
