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7.4LX MPI to Carb, what cam to use

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Old 04-17-2008, 06:29 AM
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Merc doesn't put rect port intakes on oval port heads..
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Old 04-17-2008, 06:49 AM
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I don't remember the years but they did put rect on oval.
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Old 04-17-2008, 07:48 AM
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Originally Posted by 1BIGJIM
I don't remember the years but they did put rect on oval.
I agree - I've seen it before as well.


BTW - What's worng with the MPI stuff??? Do you have ALL of it?? Wanna sell it??
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Old 04-17-2008, 06:35 PM
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The electric fuel pump in the VST is bad, and the computer reads a knock signal at all times, even with engine off. It is for sale if anyone is interested.

As for the rect. port intake on oval heads, Merc does it all the time. I will post pics if you want to see them.

Last edited by 87velocity; 04-20-2008 at 08:23 AM. Reason: typo
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Old 04-17-2008, 08:02 PM
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i'd be interested in the fuel injection system , something to tinker with if it aint to expensive
i'm thinkin with large oval heads you'd flow at least a bit more air , and with less disruption between the intake and heads would probably benifit from better air/fuel flow to the chambers , just my .02
if you wanna e-mail me about the fuel injection its usedpartsgod @ suddenlink.net
or as soon as i swipe my CC back from the old lady i'll renew my membership and you can PM me
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Old 04-18-2008, 06:44 AM
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the 049 heads will work great with a good intake, performer rpm or air gap, never understood why merc insisted on rect heads on boats... we have done lots of testing large oval vs rect and in the rpm range we run these boats at generally, the ovals make more power and torque. The rect ports do nothing for you below about 6200 on a 468 or so, and we run well below that, most of us anyway, you can get more choices with your cam, I would call comp's hot line..free call, they will steer you in the right direction, just don't shove a performance auto cam in as you will end up with a revision situation more than likely, plus a lack of power when you need it. also the weber(edelbrock) carbs work well for all around use but if you are looking for strickly performance holley will work better...Rob
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Old 04-18-2008, 06:51 AM
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I want to see the rect intake on an oval head.
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Old 04-18-2008, 07:10 AM
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Originally Posted by fastlane40
I want to see the rect intake on an oval head.

Picked up these Gen V's in Octobr - one is 1994, other 1995, rectangle on peanut.
Attached Thumbnails 7.4LX MPI to Carb, what cam to use-2x454%40607cochise.jpg   7.4LX MPI to Carb, what cam to use-gmdpintake-1.jpg   7.4LX MPI to Carb, what cam to use-b074-1liftervalleyoct2107.jpg  

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Old 04-18-2008, 08:06 PM
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Here are some pics of what I am talking about. Pics show orginal MPI intake, heads, the black intake is off of the 7.4PT (peanut ports heads also), and the blue one came off of a Marine Power 454.
Attached Thumbnails 7.4LX MPI to Carb, what cam to use-4.jpg   7.4LX MPI to Carb, what cam to use-2.jpg   7.4LX MPI to Carb, what cam to use-5.jpg  

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Old 04-18-2008, 08:09 PM
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This intake was silver, as you can see I painted it blue. The Qjet I rebuilt and painted also. I am rebuilding the Weber now and will paint it plain black before it goes on the engine.
Attached Thumbnails 7.4LX MPI to Carb, what cam to use-1.jpg   7.4LX MPI to Carb, what cam to use-3.jpg  
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