I have a 429 with an Edelbrock 750 cfm carburetor which gets about 11 miles per gallon.
The engine in a 1993 grand marquis is a 4.6 litre/281 cubic inch.
8 engine cylinders on your 4.6 liter / 281 cubic inch - V8 engine
A 1994 Mercury Grand Marquis has the 4.6 liter / 281 cubic inch Single Over Head Cam ( SOHC ) V8 engine from the factory
The 1998 Mercury Grand marquis has the 4.6 liter / 281 cubic inch Single Over Head Cam ( SOHC ) engine from the factory
As far as I know , the 1991 Mercury Grand Marquis either had the 5.0 litre / 302 cubic inch V8 or the 5.8 litre / 351 cubic inch V8 engine . The 4.6 litre Single Over Head Cam ( SOHC ) engine was used in the Mercury Grand Marquis starting with the 1992 model year Firing order of the 5.0L which is the engine installed in the 1991 Mercury Grand Marquis is 1-5-4-2-6-3-7-8 rotor turns counterclockwise.
289 cubic inches converts to approx 4.6 litres.
The 4.6 liter is 281 cubic inches
In a 1994 Mercury Grand Marquis : It came from the factory with the 4.6 liter / 281 cubic inch , Single Over Head Cam ( SOHC ) V8 engine
A 1998 Mercury Grand Marquis came from the factory with the 4.6 liter ( 281 cubic inch ) Single Over Head Cam , V8 engine
I'm not sure if the 1986 is the same as the 1987 , but ( on the 1987 Mercury Grand Marquis the 5.0 liter / 302 cubic inch V8 engine is rated at 150 horsepower and the 5.8 liter / 351 cubic inch V8 engine is rated at 180 horsepower according to my Chilton's Auto Repair Manual )
For a 1987 Mercury Grand Marquis : For the 5.0 liter / 302 cubic inch V8 engine ( 7.5 quarts of antifreeze with 7.5 quarts of preferably distilled water should give you a 50 / 50 mix of engine coolant ) --------------------------------------------------------------------------- For the 5.8 liter / 351 cubic inch ( 8.0 quarts of antifreeze )
According to one of the Ford websites : For a 1987 Mercury Grand Marquis , 5.0 liter / 302 cubic inch V8 engine : The spark plugs are gapped at ( .050 inch )