January 5, 2003ok so the timing should be set at 0 right? this isnt TDC right the zero mark is just a guideline? Also at what rpm?? idle?? also wheres the mass air flow sensor in this truck and how often does it need changing or cleaning?
Death Valley, CA
January 5, 2003O deg IS TDC....Set timing at idle (500-700 rpm)...make sure you disconnect the black/tan timing adjustment wire behind the glove box or you will NEVER be able to set the timing correctly due to the computer advancing and retarding the timing
There is no Mass Air Flow sensor on the 87-95 because they use a Manifold Absolute Pressure System (MAP) not a Speed Density System
January 9, 2003i also have a 94 gmc with the throttle body engine(350). i also thought that the timing set at 0 tdc could be improved so i played around with it as it didnt have any performance . for me 2 degrees advanced made a world of difference . it doesnt have any valve clatter and runs with power now . i also took out the stock 195 thermostat and put in a 180 . it runs a lot cooler and this temp will not effect the computer.
just my 2cents worth
January 19, 2003I have set them as high as 5 with no problems. like yelo said just make sure to disconnect the timing connector first before checking it.
January 20, 2003how can i get to this wire, on the distributor? or is it by the computer?
January 20, 2003On your 94 it should be behind the Glove Box...
Tan Wire with White Stripe on it.
It has a Unplugged type Connector on it...
Takeout the 4, 7mm screw`s and remove the carboard glove box, and you should see it, or sometime`s you can peek up under the dash under the glove box by the blower motor and see it and pull it out from there...