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Shawnandkathi

10-03-2012 03:46 PM

NOOB is it a mag or not???

Hello everyone, I am new to this forum and I am hoping someone can help me out.
I have a 96 Baja with a 7.4 bravo3 and I am trying to determine if it is a MAG or not. When I type in the serial # 0F750649 the info says 7.4L mag group. It doesn't have aluminum high rise intake which seems to be the giveaway feature of the mag engine.
I am planning to rebuild and just want to know if I have the forged goodies to work with or just the cast.
Thanks for your help.

bigredbaja

10-03-2012 04:38 PM

Quote:

Originally Posted by Shawnandkathi (Post 3789541)

I'm sure someone will be able to confirm but i believe the 7.4's are the 310hp version of the 454 not sure if they carry the "Mag" label but i do know they have all cast internals.

FIXX	10-03-2012 04:52 PM

a mag will have a alunimum intake if it has a carberator..if efi then once you get the intake off you will know..i have a snapon scope i can look in the intake with to see the intake valves if need be..

Shawnandkathi

10-03-2012 05:01 PM

I have blown the head gasket so I will find out for sure when I tear it down. I guess I'm just wishful hoping.

mcollinstn

10-03-2012 05:31 PM

Looks like a 7.4 Bravo (Gen V) 1992-1996

If it were a Mag (with THAT serial number), it would say 454 Mag, not 7.4

Sorry Charlie.
MC

Unlimited jd

10-03-2012 05:48 PM

If you do a search many of the 7.4 bravo 3, 310hp motors came with the mag intake but had small heads and cast internals. I had a late 99 version.

Knot 4 Me

10-04-2012 07:49 AM

Quote:

Originally Posted by lil red (Post 3789620)

If you do a search many of the 7.4 bravo 3, 310hp motors came with the mag intake but had small heads and cast internals. I had a late 99 version.

+1. The "Performance-Tuned" 7.4L/Bravo III with the mismatched intake/heads.

apollard

10-04-2012 08:21 AM

Most 7.4s did have all cast internals. However, some of the Bravo IIIs 'Performance Tuned" engines had the forged internals of the MAG with the aluminum hi riseintake. Otherwise, they are the same as the 300 hp 7.4 (ie, cam, heads).

From the Merc Service Manual #16:

Quote:

Note 2: 7.4L Bravo Three engines with engine code
UB with serial number OF1589289 and lower will have forged pistons.
XX with serial number OF159290 and higher will have cast pistons

From August 93 Powerboat:

Quote:

The Bravo Three uses a Performance Tuned V-8 that can be bought only with this drive as a system. The 7.4 PT's high rise mag intake, tweaked 4 bbl carb, and timing adjustments are designed to improve torque in the critical midrange.

But, as I found out with something this old, the only sure way to find out is tear it apart. It might not even be the original engine.

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