Please, I Need Help 454 Mag Identification
 

Going to test runn a boat tomorrow morning, I know it was snowing here near philly today but hey, I really want a new boat.

Thisis my issue, I read a thread recently about how to externally identify a 454 magnum motor. I can no longer find this. There is something to look for on the block, a plug or something I just can't rmemeber. Some way of telling from the outside it is a 4 bolt block which from mercruiser would make it a mag motor....

Please help, going in a few hours with money in hand. I want to make sure they are not 330's

Oh, they are gen V's

Magnum engines have rect port heads and use a high rise aluminum intake manifold. The non mag engines use a cast iron intake that is much flatter.

yeah take a magnet with you to see if the intake is aluminum. They usually have a metal tag on the carb. that says magnum

Ok, what I am now gathering is that these motors I am looking at are replacement 454 gen V motors with the fuel pumps running off of the raw water pumps.

What year did these start? I know that they can't be original as the boat is a 1988....