Correct I got the serial number off plastic cover on carb. Its not MPI I know that. The serial number can go both ways with Mag or non-mag. The cover only says 7.4/Bravo Thunderbolt ign. on it

If I pull off value cover and get case # of head does anyone know what heads are the rectangle port # and what one is the peanut port case #'s. I also read that in the Gen VI that they also put on that Gen. that are not rec. or peanut, but a larger intake ports then peanut but not as big as rec. they make it so confusing.

Ok?

I don't know of merc ever labeling a mag engine a 7.4l, looks to be a 330

Do you have access to the boat or are we gonna guess all winter?

Is the mercruiser metal stamped tag still on the block? Located on the starter side on the bell housing flange.

I do have access to boat I can check out metal stamp on block that would tell me exactly ?

Something seems funny with the carb to me. Could be that the whole engine has been modified or replaced? You cannot rely on the carb cover IMO. And I am not sure the block casting number is going to help (I thought the block was the same and the internals with the internals - cast vs forged where the difference?). If you get a shot of the intake for these guys they will be able to tell you of it is a rectangle port intake from looking at it.

Where did you see that? The serial number only pertains to one engine. Every place I check the number it comes up as 7.4L Bravo. As bus said the mag was never labeled as a 7.4. Here's some specs comparing them.
http://www.perfprotech.com/blog/arti...specifications
Accordind to this the 7.4L should have a cast iron intake manifold and the mag has an aluminum one. Take a magnet out and check it.


Type your number in here and see what comes up.
http://www.perfprotech.com/mercruise...r/searchserial

That will tell you if the number on the plastic cover is correct.

Not talking about the block casting number. Talking about the serial number on the steel tag mounted down by the starter.

What is unusual about the carb?

Number comes up as a 1997 7.4L carb engine.

+1

My 1998 checkmate 242 convincor had a 7.4l 330hp engine with a weber carb.