magnum or not??
 

Recently purchased at 1990 290 enticer, was told by owner that the engines were 454 mags?? I haven't seen any proof of these being mags. The carb covers say 454 v8/bravo, hp 330. Don't have anything about them being mags?? Where can i verify this?? Thanks guys!

post a picture of the engines

I know what motors you are referring to... they look like a MAG due to an identical intake cover but are not... if it doesn't say MAG on the plastic cowl then it isn't, it is the 330hp version. These were later switched to the 7.4 mpi's making 310hp.

you are a sponge full of information.

Haha yes, there was a 290 for sale not to long ago that was listed as 310's but to me looked like mags... I inquired about them and the guy didn't know much. So he took the numbers and called mercury to get to the bottom of it, they ended up being 330's... look exactly the same as mags but don't say mag on the sticker... same goes for the fuel injected versions

Now I'm confused. I thought the older carbed 454's were 300 hp and the mags were 330hp. Mine's a 91, and just says 7.4L Bravo One on the carb covers (nothing about "mag"), so I always thought they were 300hp. I'd be curious if someone knows how to find out from the ser #'s. Not worried about 30 hp, but cast vs forged internals would be handy to know. Thanks........

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.

I think there was a 385 hp version as well.

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.

that would be the EFI 454 mag

That is correct on the BIII but I believe he has BIs

Boatnt, thanks for clearing that up!!

Thank you!

I can post pics, but the engine cover don't say mag, it says 330hp. Thats ok though. Im gonna have to tell the previous owner this. I don't know where he got that they were mags??

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.

Yep,thats why I asked him to post pictures.

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.

Not sure that was available in '90 though.

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

Only available on 7.4/Bravo III's? I can only recall the Performanced Tuned option being tied to a Bravo III. Maybe it was available with a Bravo I as well?

Don't know. I've met one other person with one, and his was a B I. He was not the original owner, but thought it was all original. Could have been an engine swap. The manual says very little about them, just a small amount of info in the Tech manauls.

Edit: Went back and looked at a Powerboat article from August 1993 on the 257 Legend. It says the PT engine is a combo with the B III, not available otherwise. So obviously a swap out above.