the gap for the 1983 Chevy c10 silverado is 0.035 ("35 mils") 0.889mm
If it's a 1981-83 with BP7ES NGK spark Plug use a 0.032 inch gap.
The required spark plug air gap for the 83 model, 15 hp Johnson is .030 in.
'77 - '82 .032 '83 - '86 .028
6 cylinder engine is 0.045 and v-8 engine are 0.045
According to www . ford parts . com ( no spaces ) For a 1983 Ford E-150 with the 4.9 liter / 300 cubic inch inline six cylinder ( .034 inch spark plug gap )
coil is bad
try replacing the spark plugs
valve cover gasket
any solid core plug wire should work
For XR and XL 250 (pre 83 year), use NGK D8EA
YES
The schematic for an 83 Chevy 305 engine can be found in the service manual. It gives the location of each component and how everything is connected.