Specifications of a Mercruiser 7.4Lby Jillian O'Keeffe
Mercruiser 7.4 engines are on the large end of the Mercruiser engine line. Mercruiser engines are made for the marine market by Mercury Marine. The 7.4L models are the 7.4 MPI and the 454 Mag MPI.
Mercruiser 7.4 engines are V-8 and have a displacement of 7.4 liters. Maximum revolutions per minute is 4,200 to 4,600 rpm. Idle rate is 600 rpm in neutral. The eight cylinders fire in a 1-8-4-3-6-5-7-2 sequence. The 7.4 multiport injection model has 310 propshaft hp and 231 propshaft kilowatts. The 454 Mag multiport injection model has 385 propshaft hp and 287 propshaft kilowatts.
Oil pressure should be 30 to 70 pounds per square inch at an rpm of 2,000 and a minimum of 4 PSI when the engine is idling. Thermostat should be at 160 degrees Fahrenheit.
The Mercruiser has a 12-volt battery. Operating amps when cold are 65 amps and when hot, 72 amps.
Jillian O'Keeffe has been a freelance writer since 2009. Her work appears in regional Irish newspapers including "The Connacht Tribune" and the "Sentinel." O'Keeffe has a Master of Arts in journalism from the National University of Ireland, Galway and a Bachelor of Science in microbiology from University College Cork.