Originally Posted by apollard (Post 3314936)

Some of the carbed BIII's used by PQ had the forged internals (Merc manual : "7.4L Bravo Three engines with engine code UB with serial number OF1589289 and lower have forged pistons."). I have one of these in my '94 257. A long time Merc mechanic told me these also have forged cranks, but I have not verified that and the manuals says cast.

Originally Posted by boatnt (Post 3314898)

the carb 7.4 version is 330hp at the flywheel ,300hp at prop.
all cast internals,4 bolt mains.

the carb 454 mag is 365hp,forged internals and 4 bolt mains.

Originally Posted by boatnt (Post 3315003)

that would be the EFI 454 mag

Originally Posted by Knot 4 Me (Post 3315787)

You can quickly tell by the intake manifold if it is a MAG or standard motor, assuming no one has replaced the intake. The standard 7.4L has the flat truck manifold on it and the MAG has the high-rise intake on it.

Originally Posted by Knot 4 Me (Post 3315787)

You can quickly tell by the intake manifold if it is a MAG or standard motor, assuming no one has replaced the intake. The standard 7.4L has the flat truck manifold on it and the MAG has the high-rise intake on it.

Originally Posted by apollard (Post 3317954)

Actually, the "Performance Tuned" 7.4 carb motors had the alum high rise from the mag on them, but were the 300 hp motors. Done to increase low end/midrange torque in those motors.

Originally Posted by apollard (Post 3318057)

I think you're right, started in '93 I think, and short lived. Forgot they were '90 engines.