In checking photos from the early 50's, it appears
that the locos were delivered with the extended tapered stacks. Bulletin 47
shows the 307 in 1955 with the tapered stacks. Other early photos I have also
confirm this. Page 59 shows the C&S 822 and 826 with screen spark
arrestors added (you can see thru them). The photo of 407 has the screen
add on. As I posted earlier, BB 48 on page 63 shows an overhead view of BN 6049
with the original stacks.
Gordon
----- Original Message -----
Sent: Wednesday, September 30, 2015 1:27
PM
Subject: [CBQ] Re: SD 7 Exhaust Stack [6
Attachments]
Here are several photos of Q SD7s
and SD9s with spark arrestors and one photo of an SD with an extended stack
modification. Just as a matter of information, EMD's basic manifold for Roots
blown engines was considered a spark arrestor as they had baffles in them that
caused the exhaust flow to circulate with the intent to reduce spark
emissions. However, in later years, I don't believe that the basic manifold
qualified as a spark arrestor as state and local laws became more restrictive.
A concern that EMD had as after market spark arrestors were developed and
applied, was that some could and did increase back pressures within the
engine. Such back pressure could lead to problems including poor combustion
(EMD 2 cycle engines depend of clean savaging of exhaust gases when the intake
ports are open.), premature exhaust valve failures and cylinder head failures
due to overheating.
These are not my photos. While I would like to credit the individual
photographers, they are unknown to me. I have received these photos in
e-mails over the years..
Bill Barber
Gravois Mills, MO
Posted by: William Barber <clipperw@gmail.com>
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Posted by: Gordon Smith <kc2bw@optonline.net>
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