1990 GMC suburban 350 TBI timing

[scroungemeister]

I need to set the timing on this engine,(totally stock snow plow truck). a mechanic told me to set it at 0 degrees after disconnecting a tan wire with a black stripe near the distributor or back of the driver side valve cover to disable the advance signal from the advance module, I cannot locate tan wire with a male/female disconnect, the only wire back there with a disconnect is a purple wire,that is way down behind cover and I can only touch with the tip of my finger,any help out there locating the correct wire???, thanks.

[NEUMANNZZ]

just follow the tan black wire from the distributor.

[MeanGreen95]

May be behind the black plastic cover on the passenger side firewall or like mine and behind the glovebox and under the dash.

[CChase]

It's under a big black plastic piece on the firewall that holds all the fusible links.