Hi all,
Need a little help with this one. I have this motor,
MIE/340 (7.4) 454 Big Block – 4 bolt - 30 over
Block was detailed with all casting debris removed
Molly piston rings
Federal Mogal bearings (cam, main & rod)
Cloyes true double roller timing chain
Moroso Chevrolet 454 Stud Girdles #6729 BBC
Crane #99277 lifters
Comp Cams High-Tech pushrods #7954
Completely refreshed Chevy 14096188 heads / 454 Open / 118cc / 3angle valve
Comp Performance Valve Springs #911-16
Pioneer head bolt sets
ARP 1.90 rocker studs
Norris S/S 1.7 roller rockers
Melling H/V oil pump
Melling HV oil pump shaft.
EDELBROCK BBC R2 AIRGAP INTAKE
JEGS 15951 - Mechanical Fuel Pump
ProComp ignition
Pro Comp distributor
Super Stock coil.
8mm Accell Hi performance wires
New single wire alternator
Mini (gear reduction and fully marine) starter
Edelbrock 800 carburetor
Edelbrock oval air cleaner (with K&N filter)
Brass freeze plugs
Stainless steel bolt set
4” Stainless steel risers
GLM aluminum manifolds
Sherwood motor mounted raw water pump.

I’m taking this out;
Stock seasoned crank
Reconditioned connecting rods
ARP Rod bolts
.210 Domed Speed pro pistons and pins. (They should give me 9.38 to 1)

And replacing with,
Scat 4.25 Crank
Scat 6.385 Rods
K.B. Pistons -17cc Solid Dome Top
With the heads I have it should get about 10.25 (maybe) to 1.
Is this cam good enough for this set up?
Crane #132561 hydraulic cam--Duration Advertised: 298° Intake / 306° Exhaust Duration @ .050'' Lift: 228° Intake / 236° Exhaust Valve Lift (w/1.7 Rockers): .530'' Intake / .551'' Exhaust Lobe Separation Angle: 114°

I wouldn't go with any more duration but you could use a little more lift. I run pretty much the same set up except mine is bored .100" over for 505 cu. in's. I run a Ultradyne 296/304 with .575/.600 lift. Only a 23' single engine but works very well.

That is a good cam though.

There are a few other things you might want to check out. One being the fuel pump, it is to small for that engine.That pump is only 80 GPH and has 1/4" lines. That thing can lean out your engine on the top end and burn up pistons or valves. You need something more like the Holley 712-454-13 marine pump which pumps 130 GPH and uses 3/8" lines.It would have been a good idea to put Inconel exhaust valves in when you were having the valve job done due to the extremely high exhaust temperatures of a marine engine. Another thing is a high volume oil pump isn't really needed on that motor. If you are using a stock pan there is the possibility of pumping it dry.It also uses more power to turn it.Also if you are changing to a negative 17cc piston top your compression is only going to be around 8.75 to 9 to 1. You need a flat top which would give you more like 9.5:1. Also you could use a 850-1050 CFM Holley or Demon MARINE carb. Holley has a calculator on their web site that can tell you which carb is recommended for your engine .Don't really need a stud girdle on that motor either.

Just my 2 cents.

Sorry, I don’t think that is a “-“ mark, I think it was a dash. According to KB they should give me 10.25 to 1.
It has a 8qt pan. As for the carb, I feel safe. It is an off road Edelbrock and having them side by side with a 750 Edel Marine there is no difference except for the fuel pump over flow input and that was a simple fix. Inside and out they are the same. That is why I only use Edelbrock. Maybe not the best in the world but they are simple and defiantly can take a licking and keep on ticking.
As for the fuel pump. I have all big lines to and from the tank to the pump to the carb but I will have to look into fuel flow. Thought it should be OK being a normal 454 only needs a 43gph and mine almost doubles it but …….
I’m not trying to build a monster. About 500hp is the limit for my old Volvo drive. I also wouldn’t mind bring back my cruising RPM’s back a little. I’m more into it for the torque. Even though the boat is 19 feet long it is a big old heavy boat. Built by Allmand in 1972 and is 8’ wide at the transom. There is a lot of ass to move around.

That looks like a flat tappet cam. Do you have the money for the roller setup. I have been through all this before with the off the shelf cams. Last year I went with a full roller setup from RMbuilder, cam, springs, timing chain, ect..... I gained 5MPH plus the boat idles better, plains quicker. That will give you way more power than switching out all the other parts. Before you spend any money I would give him a call, tell him what you have and what your goals are. Best speed return for for the dollar I have spent.

I just took another look at your post. Do you have long risers? Did you upgrade your oiling system?
I have a 489 stroker also. The forged rods and forged stroker crank are a good upgrade.

Ya, it’s a flat tappet. It’s the infamous “420” cam. Last spring I thought it would wake up the motor a little but I was not as happy as I thought I would be.
The stroker kit is bought. It was kind of a gift in a long story. Along with a couple Gen V 454’s I just finished up for the race boat (pretty much stockers) the stroker has become a side project for a boat that if a boat ever need a stroker it’s this one.
As for oil, I planned on adding a oil cooler (I already have it also). It does have one of those big thick aluminum pans already.
As for exhaust. I have the GLM’s now. I have been open to upgrading for a while so it is on the list.

Like I said, I’m not to looking to build a monster. To be honest I wouldn’t mind a little more top end but the main goal is to bring down the cruising rpm. Not that I am world traveling with the boat. Maybe 5 to 7 mile runs at a time but I find myself “cruising” around 4000 rpm’s. Thought this would help

I would consider a roller cam and upgrade the exhaust. At the very least if you decide to stay with hyd. flat tappet I would consider a better one than the 420 HP cam. Those are a decent cam for a 454 however I think you'd be wasting your CI and all your other mods with that one. I ran it for a few years in a 454 and it worked well with all other stock components. I know what pistons your talking about and that might be a little much unless you hog your chambers out to around 124 cc's or so. That would be easy to do or otherwise look into thicker head gaskets. At least with a little chamber work you'll improve performance as well.

Like Jeff said call Bob or otherwise Gellner Racing for your cam needs. Dean G. helped me out a great deal with cam specs for my 496's. Valako is another wizzard when it comes to power. All depends on what your looking to do. Your package is near many out there with already proven cams. So if you choose to find one on your own it should be pretty easy. You'll also gain a great deal of power with some after market heads however I know this gets expensive but you can always look for a good deal on a used set ready to go and sell yours. You should easily get over 500HP with a rather conservative set up though.

thats going to be bigger than a 489 w/.030, std bore 454 and 4.25 crank is 489...Rob

the 561 cam is NOT the 420 cam i believe the 531 is. The cam you have is bigger than that one.