Of course if you talk with ten different cam grinders and/or engine builders, you'll get ten different opinions as to which camshaft you should use in your engine.

If you were to remove the current camshaft from your 1979 engine and install the Clay Smith cam shown above, and add ported D3VE heads/Edelbrock Performer RPM intake/Edelbrock 1410 750cfm carburetor as you intend, you might make 425 hp.  The engine will not generate 475 hp in your boat.  It will not generate 450 hp. It might make 425.  Perhaps it could generate more on a dyno at a higher rpm, but your jet pump won't allow it to get there and you'll never experience it in your boat.  Part of the reason for the unexpectedly low resulting power is the camshaft choice itself, another part is the overall engine combination relative to the new cam (although your newly acquired engine in its current state is a fine parts combination). 

If I were building a 460 engine for a jet boat and stuck with using that camshaft, the build would need to have tubular over-transom headers.  Then the power output might get to 475 in your boat.

The peak valve lift advertised on the Clay Smith cam card is right at the point where it would be highly advisable to machine down the D3VE's valve guides for more retainer-to-guide clearance and simultaneously convert them for snap-on stem seals (rather than the OEM umbrella-type seals).  The OEM pedestal valve train could still be utilized including the stamped steel rocker arms if properly set up with pedestal shims and correct pushrod lengths; aftermarket pedestal roller rocker arms might be a nice upgrade but not entirely mandatory.

hmm... choosing the correct camshaft is some science
I have no clue about it, and when Clay Smith recommended one, i felt kind of relief knowing what to buy.

So, @LakesOnly, is it possible to recommend another camshaft for me, who will suit me better?

Or, is the camshaft the right one for my build, i'm just going to see less hp than Clay Smith thought?
As you see at my boat type, over-transom headers is not an option.


Regarding those iron heads, they have valve springs with damper, and are converted to snap-on stem seals.. might be hard to see on the pictures but.
The exhaust valve seats are replaced and stainless valves are put it.
I am thinking of converting to roller rockers, the guy who got the heads right now will fix so i can mount studs, he will also fix the valve guide for more lift if it is needed.

As you see on the pictures, the heads are actually E8TE, but i've read they are exactly the same as the "more known" D3VE, so therefore i wrote that number.
 

I think that by the time you had those iron heads ported and modified for roller rockers, you could buy a set of aluminum heads, and get more power and lighten the weight as well.

Because of the desired compression ratio and the exhaust risers that shall remain in the boat, there are only two aluminum cylinder head choices with the correct chamber size and correct exhaust port/bolt pattern: 95cc Procomp heads or 95cc Edelbrock heads.  The Procomp heads will make LESS power than ported D3VE heads; that leaves the Edelbrock heads.

The cost of a new pair of 95cc Edelbrock heads is $2500.  And when you bolt them on, the engine will still not generate the power desired--you will still have to spend more money (cam, etc).  That is not cost efficient, nor is $2500+ dollars "less than ported D3VE heads."

The cost of a used pair of 95cc Edelbrock heads is $1300-$1400.  You are then well advised to run them through a machine shop for inspection, touch up the valves and valve seats, new stem seals, etc, adding up to at least another $300.  And when you bolt them on the engine will still not generate the power desired--you will still have to spend more money.  That is not cost efficient, nor is it "less than ported D3VE heads."

If the OP has settled for less than 500 hp desired, then why the excess expenditures on such unnecessary items?  I admit I do think in the most practical terms rather than "show" or "shiny," but then again show & shiny do not make horsepower.  And, greater horsepower supporting components do not equal practical.

Just get a combo-correct cam, bowl blend the iron heads, and maybe execute a 7/16" rocker stud conversion.  Done, and the cost of such mods ought not exceed $1000.

Thanks for sharing knowledge about this.

I'm repeating myself, but..
Do you mean the Clay Smith recommended camshaft is OK, it's just that i really should have a higher compression ratio and a better exhaust? -to get better use of it

OR should i buy another camshaft?

If no no other camshaft will give me any higher HP because of my exhaust/compression i think i'm just going to go for it..

And then it's the question regarding the lobe separation.
Clay smith at first recommended 108 degree, that would be no problem they said because of my exhaust type, but they could also grind 110 degree on the same camshaft, would also work well they said.
 Would i loose much power with that?

Lots of questions, but i'm struggling here 

As lakes only mentioned, you can talk to ten people and get 10 opinions. I would honestly go with what ever he recommends for your set up. George (the owner) has been building engines for jet boats for a very long time. He won’t steer you wrong. I think your exhaust is going to hold you back from the full potential so I’m sure he won’t recommend anything to aggressive because it would just be a waste.


Sent from my iPhone using SoCal Jet Boats mobile app

Since the conversation started here i sent you a PM.