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7.4L and merlin heads

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Old 09-17-2005, 08:25 AM
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Default Re: 7.4L and merlin heads

Originally Posted by sutphen30
just do a search for "330hp on steriods" all the info you'll need.those heads you want to get can make some serious power so make sure of what you want for total power first.most every hp combo up to 600hp for a 454 can be found online.
i have no set hp goal i just want to go 4-5mph faster than i am now (61mph gps) but i want to be able to use my boat and not work on it everyday, and not having it break or blow up.
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Old 09-17-2005, 09:34 AM
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Default Re: 7.4L and merlin heads

i am going to use a wet system. prob. the dana marine flo-torque manifolds and the down sweep risers to fit under my swim platform. i guess i am shooting for as much as i can make on a stock bottom end. the engine is a new reman and has only like 6hrs on it.mybe 400-420hp so i want to keep my mods in the top end and while keeping it on pump gas 89/91/92 octane.
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Old 09-17-2005, 10:17 AM
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Default Re: 7.4L and merlin heads

Better stick to something like a Crane 731 hyd roller then. Anything larger will cause reversion. That will still be a big jump up from a stock cam. It won't be hard on valve springs, you should get a couple hundred hours out of it before you need to look at the top end again. You will need a good set of roller rockers though.
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Old 09-17-2005, 10:25 AM
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Default Re: 7.4L and merlin heads

the heads already have nice vavles and dual valve springs in them. these are the specs on the heads
Intake valves are 2.250 Manley severe duty and Exhaust valves are 2.190
Manley Inconel. Valve springs are roller lifter variety for up to .650
lift. Studs and guideplates shown are included.

Porting was done by Todd Goodwin at www.goodwincompetition.net.

Flow numbers are intake = 350 cfm @ .600 lift and exhaust is 280 cfm @ .600
lift.

what cam and roller set up do you guys rec. for this.
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Old 09-17-2005, 03:10 PM
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Default Re: 7.4L and merlin heads

454 w/Merlin heads, 731 cam, Air-Gap intake, BG850dp, 9:1 CR, Stainless Marine exhaust 487hp
Attached Thumbnails 7.4L and merlin heads-487hp.jpg  
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