no more than .035
( .044 inch ) according to motorcraft.com
fordparts.com shows .035 inch for two spark plug numbers and .030 inch for another spark plug number ( I believe the .030 inch is for heavy duty use )
According to one of the Ford websites : For a ( 1960 ) F-100 , 3.6 liter / 223 cubic inch six cylinder engine : ( .035 inch spark plug gap )
According to one of Fords websites : For a 1963 Ford F-100 with the 4.8 liter / 292 cubic inch eight cylinder engine : ( .030 inch spark plug gap )
Ford uses Motorcraft Spark plugs on all there vehicles.
According to one of Fords websites : For a 1967 Ford F-100 , 352 cubic inch V8 engine : ( the spark plugs are gapped at .035 inch )
.035 inch ( light duty ) .030 inch ( medium duty ) according to fordparts.com
no plug on trans pan----u have to drop the pan
According to one of Fords websites : For the 5.0 liter / 302 cubic inch V8 engine in a 1978 Ford F-100 : ( the spark plugs are gapped at .044 inch )
The spark plugs on a Ford Explorer are replaced by first disconnecting the battery. Remove the spark plug using a spark plug socket. Replace with the factory recommended spark plug.
the spark plug gap is .054in. for 2003 ford focus.