454 carb'd mag vs reg...

[2FORCEFULL]

whats the difference...

 

[Snprhed]

385 hp for the Mag, 300 hp for the standard 7.4L

I believe the Mag has forged pistons and crank also, good candidates for power adders

 

[240Hallett]

I have a non-Mag in my 89 that was rated at 330 horse.

 

[Cdog]

My 1990 carbed 454 mag has Rectangular port heads, roller rockers, forged crank & 7/16 rod bolts. Its rated at 365 hp but Ive read thats rated at the drive. The later versions are rated at the crank.

 

[Deja_Vu]

I've always wondered about this.

I have a '97 7.4L and wasn't sure if it was 300, 310 or 330 hp.

 

[Cdog]

Engine only has 160 hours on it. Are these the crane rockers that were made for mercruiser?

 

[OC Mike]

My 95 non mag had 330hp. I believe the Mag also has better heads along with the better lower end. I was told at the time the Standard 330 hp was not a good candidate for power adders whereas the Mag was. May even be 4 bolt main. Short story, mag can be hot rodded. Leave the non mag stock.

 

[240Hallett]

My 91 Mag is 365 horse.

 

[Cdog]

My 95 non mag had 330hp. I believe the Mag also has better heads along with the better lower end. I was told at the time the Standard 330 hp was not a good candidate for power adders whereas the Mag was. May even be 4 bolt main. Short story, mag can be hot rodded. Leave the non mag stock.

330 hp has cast crank, oval port heads, 3/8 rod bolts I believe.

 

[OC Mike]

That’s what I remember, just wasn’t positive. The Mag has the good stuff.

 

[RCDave]

I had a marine power version of that motor and was rated at 390 HP. Excellent engine. I put over 400 hard hours on that engine to a jet drive. Most of it pulling skiers. Ran as hard when I sold it as it was brand new

 

[Snprhed]

You will see a lot of 330hp from earlier versions but that was crank HP its the same as people who say 300 hp (its just the prop rating)

 

[Deja_Vu]

Mine is the 300HP at the prop shaft. This is for model years '93-'97
Serial numbers are located on a I.d. plate near the starter.

 

[Runs2rch]

The 310 hp version was pre 93 right?

 

[UltraLucky]

https://www.perfprotech.com/blog/bo...es-block-id-codes-big-block-v8-marine-engines

Best way I found for determining what long block you actually have.

 

[Cdog]

I have a serial # tag on my engine.

 

[92562]

For 1995 I know that the difference between the 330 and 300 was that the 300 had the low profile "flat" intake manifold and the 330 has a hi-rise dual plane manifold. The initial timing on a 330 was 10 degrees and the 300 was 8 degrees. There may be other differences too.