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-   -   454Mercruiser Intake question (https://www.offshoreonly.com/forums/general-q/267767-454mercruiser-intake-question.html)

HaxbySpeed 12-27-2011 10:08 PM

They didn't come from GM like that, but lots came from Merc. I think it's when they started using the truck long block but weren't using the MPI truck intake. Must've had lots of the square port intakes in stock. Lol.

Unlimited jd 12-27-2011 10:10 PM


Originally Posted by Baja226sport (Post 3579720)
I would be willing to bet someone got their hands on the aluminum high rise intake and weber/carter carb and thought that they were making a performance upgrade.

They probably figured that was the difference between the 7.4 Bravo and 454 Mag.

I know it is a little different but just as an example I do tons of work and sales with outboards and you wouldn't believe how many people think that they just slap the carb from a larger model on their motor and it becomes that hp!! I see it and hear it all the time!

Or they repowered with a cheaper long block and didn' t realize that the intake/fuel system was different. See that alot too!

weird how some people try and piece garbage together and pass it off for something its not!! at least this was advertised as a 454 300

charliem 12-27-2011 10:37 PM

That combo worked better with the carter carb. The only intake they had with the small port was the cast iron junk that did not work well with the adapter and the carter. It filled the gap until the gen 6 efi

mike tkach 12-27-2011 11:26 PM


Originally Posted by charliem (Post 3580542)
That combo worked better with the carter carb. The only intake they had with the small port was the cast iron junk that did not work well with the adapter and the carter. It filled the gap until the gen 6 efi

mercury is all about making money,if they wanted to do it right,they could have bought aftermarket manifold for them,but i guess that would have cut there profit margin.:party-smiley-004:

ezstriper 12-28-2011 06:26 AM

no, I think they just wanted to have one intake to use on a few different engines..they used that intake on a bunch..thats why they were done for holley & Q-jet's 1st one I saw I said no way came that way...then ran into a few more, some I knew were never apart...nobody said merc never did dumb stuff...

88Spyder 12-28-2011 08:00 AM

Nothing surprises me anymore, after working for G.M. for about 25 years and having my transmission shop, most of these company's are just about the profit margin and using what they have hanging around.

endeavour32 12-28-2011 08:17 AM


Originally Posted by 88Spyder (Post 3580659)
Nothing surprises me anymore, after working for G.M. for about 25 years and having my transmission shop, most of these company's are just about the profit margin and using what they have hanging around.

Exactly! A freind of mine was a quality control manager at GM from the 70-90's and he said you NEVER stopped the line for any reason! You were told to do what ever was needed to keep the line running! Looks like Merc had the same attiitude! I have to say that is shocking, especially considering what Merc charges for an engine!

apollard 12-28-2011 09:11 PM


Originally Posted by mike tkach (Post 3580518)
WOW,wonder why ,i wonder if maybe they needed to fill an order,so they just used what they had,i think it would run better with the small oval port manifold.do you think it came from gm like that?

Merc built them this way on purpose on the early Bravo III engines - called it the Performance Tuned engine. Had the Mag intake on small oval heads, different carb calibration and a recurved distrubutor. Supposedly increased mid range torque for cruisers, etc that used the BIII. I have one in my PQ.

From the August '93 PowerBoat:

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.

88Spyder 12-29-2011 05:25 AM

I can see where they would need to play around with the carb and advance as this combo must have leaned out the @@@@ on the motor, funny because the motor actually has a burned valve in it!!!!!!!!!
I know I'm fairly new to the whole boat engine thing but a drag motor would never survive with that combo,let alone have any kind of performance.

tony davis 12-29-2011 05:57 AM


Originally Posted by apollard (Post 3581280)
Merc built them this way on purpose on the early Bravo III engines - called it the Performance Tuned engine. Had the Mag intake on small oval heads, different carb calibration and a recurved distrubutor. Supposedly increased mid range torque for cruisers, etc that used the BIII. I have one in my PQ.

From the August '93 PowerBoat:

Correct, I bought one around 97 from our Mercruiser distributor, on a B3.


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