The 3.0 L VULCAN engine used in the Ford Ranger is a very good engine , I would choose that engine or an older 4.0 L OHV rather than the 4.0 L SOHC with its 3 timing chains
.044 inch ( according to motorcraft.com , one of Fords websites )
According to one of Fords websites : For a 1989 Ford Thunderbird , 3.8 liter V6 engine : The spark plugs are gapped at ( .054 inch )
According to one of Fords websites : For a 1991 Ford Explorer , 4.0 liter V6 engine : ( the spark plugs are gapped at .054 inch )
According to one of Fords websites : For the 1992 Mercury Cougar , 3.8 liter V6 engine : ( the spark plugs are gapped at .054 inch )
The 3.0 liter and 4.0 liter V6 engines have ( 6 ) spark plugs The 2.5 liter 4 cylinder engine has ( 8 ) spark plugs with Fords twin plug ignition system
According to one of Fords websites : For the 3.8 liter V6 engine in a 1988 Mercury Cougar : ( the spark plugs are gapped at .054 inch )
According to one of Fords websites : For a 1994 Mercury Villager , 3.0 liter V6 : The radiator cap is ( 13 PSI )
On a Mercury Sable , V6 engine : firewall 1-----2-----3 4-----5-----6 front of vehicle > driver
According to one of Fords websites : For the 3.0 liter V6 engine in a 1993 Mercury Villager : ( the spark plugs are gapped at .032 inch )
According to one of Fords websites : For a 1994 Mercury Cougar , 3.8 liter V6 engine : ( the spark plugs are gapped at .054 inch )
According to one of Fords websites : For a 1990 Ford Bronco II , 2.9 liter V6 engine : The spark plugs are gapped at ( .044 inch )
According to the 2006 Ford Ranger Owner Guide : The 3.0 liter V6 takes ( 5W-20 ) The 4.0 liter V6 engine takes ( 5W-30 )