Paul-
Getting ready for the return of my engine, and I need to get the
welding
on my exhaust reworked. Based on prior discussions here on the list,
I
know I must get the exhaust tubes rewelded to the inside of the
mounting
flange. Before doing this, though, do I need to remove the exterior
welds, or are welds on both the inside & outside acceptable?
Mark
The heat damage is done already to the metal alloy. Can you
shorten them about 3/8ths of an inch and just weld them on the
inside? Are they 321 SS and .065 thick?
I have no idea what the thickness or composition of the exhaust is --
perhaps Jerry could comment since he fabbed them for me.
As you can see in the pic, shortening the tubes is not in the cards -
the body of the exhaust VAM is already less than 1/4" from the mounting
bolts. Right now I have to install the nuts while the flange is only
partially mounted in order to get the nut to fit. If I cut the tubes
down at all, it would be impossible to mount.
Also - I note in your 3D that you show the tube fully penetrating the
mounting flange. I believe in my muffler that the tube is
surface-welded to the outside of the flange (no penetration at all)
Given all this, am I correct in assuming that the tubes must be wholly
replaced & the flange bored wider for new tubes?
Mark
OK then fabricate some braces up to the engine block.
I'll do a 3D shortly. That will reduces the stress on the joints.
Order a couple of these things from McMaster Carr.
We will use the old intake manifold bolt holes.
----------------------------------------------
On second thought Mark hold off ordering those springs.
I have just thought of what might be going with these
frequent cracking of tangential mufflers feed tubes.
The main vibration mode of the rotary is torsional about
the e-shaft axis. That whips the mufflers up and down. Perhaps
at some multiple of the muffler resonant cantilever bending
frequency mode when the engine is running at a constant RPM.
Consequently it fatigues the tubes where they
are welded to the flange. I think what we need is a rigid
connection and let the straps and tubes bend slightly. The
springs might aggravate the situation.
I'll do a 3D.
OK here it is. Make a couple of straps out of .065 thick
4130 one inch wide. Skip weld to the ends of the can.
--
Paul Lamar ...No rotor no motor.
--------------------
Paul,
Why couldn't Mark just take a slip-to-fit tubing inside the current
manifold, inserted from the flange side, about 2" long, and have it welded
on the inside, then use a spring retainer in case the outside weld cracked.
The spring would hold the tube to the flange, and the exhaust would flow
through the inner tube into the existing manifold.
Bill Schertz
KIS Cruiser # 4045
Yes he could do that but Mark was mis-informed. It was welded
correctly.
That is a very very good idea for everybody however.
The double tubes would tend to dampen vibration as the inner
tube would expand more than the outer tube due to the fact it
would run hotter. Excellent idea Bill.
Burns SS carries 1 7/8 321 .065 wall tubing.
http://www.burnsstainless.com/321tubing/Straight321/straight321.html
Paul Lamar ...No rotor no motor.
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