Dear Iain, Walt, and mid-60s Buick caregivers,
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Got another question here: Anyone used that sleeve wiring protector stuff? It's fiberglass.
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As it turns out, Greg and the gang at Orinda Classic Car used the fiberglass wiring protectors extensively when they upgraded Biquette to the FAST Sportsman EFI system. Here is an example around the ignition coil:
Here is an example on the firewall with the wiring that in part connects the fuel pressure sensor to the ECU:
They also used plastic conduit for larger bundles.
Here is one more example of wiring going from the driver's side to the passenger side over the radiator:
So these sort of wiring protection are suitable for automotive use at least if you buy the products intended for that purpose.
I hope that's some additional help!
Cheers, Edouard