| Re: [GMCnet] Doug Thorley Headers D755Y vs 355YC [message #325895 is a reply to message #325889] |
Thu, 09 November 2017 14:20   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
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Senior Member |
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There is a direct relationship between governor gears, speedometer cables,
transmission shift cables and headers. It is kind of a "Yeahh-Boooo" one.
Let's say you have a cracked cast iron exhaust manifold, can't find a
replacement, so, you choose to install a set of headers. If you spend a bit
of time under the hatch, you will notice that a header tube runs parallel
and quite close to the speedometer cable, especially if you have a gearing
change in the final drive and install the correction gearbox with the exit
cable up instead of down. All that header heat melts the outer covering of
the speedometer cable, fries the cable lube and before long, the cable
freezes up. This shears the governor gear, and you need to remove the
governor to fix the gear. So, along comes the bright idea to move that
header tube to provide clearance to remove the governor. Ahhh Haaaa,
problem solved, right? But wait, when the header got re-designed, one of
the tube now comes close to the transmission selector cable. Guess what
happens, next. The shift cable does what the speedometer cable did, and you
can't put your transmission in gear. All that I am saying here is that when
your headers are installed, your job is only half done. You need to make
some effective heat shields to protect those cables, no matter which design
you choose. If not, don't say you didn't read it here before you are broken
down beside the road.
Jim Hupy
Salem, Or
78 GMC ROYALE 403 with reduction box, Doug Thorley headers, and new
speedometer gear and governor gear. Yes, I learned the hard way, but you
don't have to.
On Nov 9, 2017 11:28 AM, "Larry" wrote:
IMHO, you only need to have one Governor gear go out for that header to pay
for itself. Lots of us carry an extra gear and there have been a number of
inquiry's on this net where the trans would not shift out of first and it
ended up being that governor gear. Just say'n...
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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