On Jan 27, 2011, at 7:20 AM, JonSmith wrote:
> is it considered acceptable for the electric tacho wires to pass
> through the firewall via the multipin plug/ socket connector that I
> have all the other low current things going through (oil press/
> temp, starter solenoid control wire etc etc) or are the tacho wires
> subject to interference and should thus be routed separately?
All,
Every so often I read a post which gets my attention and prompts me to
reconsider aspects of my build...this is one of them.
As I've posted previously, my engine is a MPEFIed derivative ot the
Sube EA81which arrived w/ a fully complete and dyno-tested wiring
harness in a nice, neat, and tidy bundle with several rectangular 15
and 27 pin Dsub connectors intended to be plugged into the ECU (shock
mounted aft of the firewall) and a small control unit to be mounted on
the instrument panel.
In the process of mounting various sensors on the engine (EGT
thermocouples, oil temp. & pressure, coolant temp. & pressure, etc.),
I have a second bundle of wires...both bundles, of course, must
penetrate the firewall in some manner.
With a fair amount of ignorance and naivety, I have been loath to mess
with the ECU bundle; consequently, I've cut a slot in the firewall big
enough to slide the 27 pin Dsub connector thru and fabbed a cover
plate from firewall material which is secured w/ nutplates w/ a hole
sufficient for the bundle. A short length of split rubber hose
surrounding the bundle is intended to protect the wires from wear
against the raw edge of the firewall and cover plate.
With regard to the sensor bundle, having been advised to avoid
connectors in the thermocouple wires leading to my EMS unit which
degrade their accuracy to some degree, I have similarly drilled the
firewall and installed a rubber grommet as shown.
A couple of photos are attached.
Prior to flight test, it's my intention daub on a bit of RTV sealant
to stop any air leakage; all of the above appears to be consistent w/
techniques used for firewall penetrations on my 1946 Stinson.
Informed comment would be much appreciated.
Please be gentle,
Fred
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