Re: 7.4L and merlin heads
 

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. :eek:

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.

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.

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.

Re: 7.4L and merlin heads
 

454 w/Merlin heads, 731 cam, Air-Gap intake, BG850dp, 9:1 CR, Stainless Marine exhaust 487hp