My "winter upgrades" to my 454 has changed direction a bit. I found a small problem with the peanut port heads that were on the motor and sense they would have needed some work and I'm bolting a large oval intake in the motor I decided to upgrade the heads to the 049's. The heads I bought have bigger valves in them (2.19 int & 1.88 ext). Sense I have gone this far........I am tossing around the idea of changing the cam.
Has anyone thrown a set of 049's or 781's on a stock bottom end of a 454 (330hp) and put a cam in at the same time???? I'm wondering if I'm going to run into piston to valve clearance problems with the bigger valves or more lift? I'm looking at bringing the lift up to somewhere around 0.530-0.540 but due to the stock bottom-end don't want to spin past 5,000rpm for now.
Any recommendations on a good preforming hydraulic flat tappet cam would be helpful. Thanks guys!

Should be no problem with valve to piston clearance using a cam with lift in the range your considering. As long as you stay under .600 lift there should be no worry. The intake your using I hope is a dual plane. You would want to use a 750 CFM carb on that also. Comp cams make some good marine cams at a reasonable price for a upgrade like your doing. The 262 or 270 would probably be what your looking for. Here's a list of their cams at Jegs. Next thing you might want to consider is exhaust. Everything has to be compatible for best results.

http://www.jegs.com/p/Comp-Cams/Comp...47427/10002/-1

Thanks for the info and suggestions! I have quite a bit going on with this motor this winter. I bought a holley 750dp, stainless marine exhaust, a performer rpm, roller rockers, 3/8th's push rods, msd ignition, a cross-over, etc... and now heads and a cam. Should be a nice running motor when I finally get it back together.

Several years ago my cousin rebuilt/upgraded his Merc 330's and used some old junk truck GM oval port semi open/closed chamber heads and installed the larger stainless 2.19" and 1.85" valves. The 1.85" actually breath better than the larger 1.88" valve---bigger is not always better. He also used a Comps Cam FLAT tappet hydraulic something like 222*/226* at .050" lift on 110* lobes and .515"/.515" lift, dual plane aluminum hi-rise intake, Holley carb, stock Merc Thunderbolt ignition, 8.6 comp ratio. The heads were pocket ported and flow tested by JimV and he also did a "Bore Notch" job on the cylinders of the blocks. The engines made 461hp @5100rpm and 500+ lbs of torque on Tom Earhart's dyno. He installed the engines back into his 32' Baja, added GIL dry exhaust system and noticed a very noticable pick up in speed and throttle response/torque and saw an increase of about 10-12mph on top.....especially in the midrange cruising speeds.

Anyway, Hope that helps you a little

You won't have any clearance issues with a moderate cam. If you upgrade the cam to more than about the size of a 454mag, you will need aftermarket exhaust with longer risers.

Hey Griff,
Fortunately, I bought stainless marine exhaust (gen 2) about 3 weeks ago. I never expected this project to take the turn it has but I suspect I'll be pretty happy with it when it's back together.

Hey Kaama,
I have a friend that's really sharp with bbc's (he won fastest street car shoot out back in the early 90's) that's going to supervise me on some some light port work and unshrouding in the chambers. I'm a little concerned about the lack of compression so hopefully we can deck the heads to get the compression ratio up a little or at least back to where it's at now after the chamber work is done on the new heads. If I can get 425-450hp out of this thing, I'll be happy. The boat is a 89 warlock euro 24 so it's pretty light. I suspect I'll feel some solid gains from everything I'm doing!

"Bore Notching" is notching the top of the cylinder at the deck correct? If so, I'm not going to be able to do that because I'm not pulling the motor. The only change to the short block is going to be the cam and timing chain. I have also bought a hp-6 filter head and replaced all the restrictive 90 degree fittings with summit push-lock -12 fittings and hose. I'm also considering a better cooler at this point but don't know if it's necessary with the hp this motor is going to put out.

Hey guys,
What do you think of this cam for what I'm doing? It's a Lunati Voodoo camshaft.

Advertised Duration (Int/Exh): 262/268
Duration @ .050 (Int/Exh): 219/227
Gross Valve Lift (Int/Exh): .530/.542
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1400-5800

Cam and timing chain swap without pulling the motor - may be a little challenging.

I used this cam with good results in a 454mag. Its also budget priced.

Crane #134241 #134242 is cam kit with lifters

http://www.summitracing.com/search/?...d=134241&dds=1
http://www.summitracing.com/search/?...d=134242&dds=1