454 and Berkely 12 JE performance

[GCJ]

Hello,
New member and some (maybe obvious?) questions. Not obvious for me anyway, because I don't know what I can expect.
I have a 454 magnum (454 EFI GEN. V GM 454 V-8 1994-1996) with the following parts:
- Holley 750 cfm four barrel (type 4150)
- Edelbrock performer RPM.
- Gen IV rectangular port heads.
- Mallory YLM magnetic electronic distributor, MSD coil.
- I don't know what kind of camshaft, but I assume the stock one.
- 4" exhaust system (Indmar) with in-line & slip-in silencers.
For propulsion it has a Berkeley 12 JE with hydraulic Place Diverter and an AA impeller.
Pump was bought new in 2000 and has run around 75 hrs right now. The same hours apply to the engine which was an MPI originally, but was converted to a carburetted engine.
Anyway, I am seeing 4200 RPM max. at WOT. Is this what I can expect from this combo? If I read the Berkeley chart right it effectively delivers around 280 HP at 4200 rpm. The factory specs tell me this engine (totally stock) should deliver around 350 propshaft HP (but propably at 4600 or maybe more RPM?).
Any insights about the performance of this engine?
I didn't check compression etc.. yet, only the base ignition timing which looks ok @ 8 degrees advanced at 650 rpm.
Thanks in advance for your help.

[IMPATIENT 1]

sounds about rite for a stocker.if ya want it faster, better plan on some mill mods, ya need more power if you want more rpms. sounds like the pump is loading well though which is a good thing!

[TIMINATOR]

A Comp 288 cam will wake it up, the 292 might fit but it is likely that the valves will slightly hit the pistons. Seen 'em work, seen 'em not. The impeller is too tight for a square port motor. An oval port deal makes more power below 5500-5800 rpm. I have put that motor in a Carrera 205 with a AA impeller to replace a stock 330 hp peanut port motor, they ran within 1 mph of each other until I put a cam, big exhaust, and cut the impeller to an AB. TIMINATOR

[CARLSON-JET]

GCJ, I have the same gen-V bottom end bored .020 over. pistons - .020 down in the hole. I run gen-4 781 heads with pollished chambers, mild bowl work, filled crossovers and the small valves. had the heads shaved about -.010. CC'D to 117. Intake is a G.M. performance dual plane. cam is a crane 278int. & 292 exh. I also run comp roller tip 1.75 rockers. carb is a weber 750 marine (edelbrock/carter style) I believe the effective compression is about 8.5/1 or less. Hardin log manifolds and the small dia. snails. the cam IMO is a bit big but was what I had. I turn an Aggressor A @ 4400-4500. It seems to me you have low compression, alot of port and a little cam. [(edit:)I would find out what cam you have first. ] Timinators recommendation sounds like a solid plan. I would start with the cam then exh. then impellor changes in that order. Or borrow another imp. to see if you can get the rpms up a bit while gaining speed. R.B.

[GCJ]

Impatient, Timinator & Carlson Jet,
Thanks for your replies and recommendations, I appreciate that.
Can I conclude here that any engine comparable to mine and which is dialed in right (ignition, fuel mixture etc..) will not be able to turn more then 4200 RPM considering the AA impeller? In other words with the parts I have it's running as 'happy' as possible and I am loosing approx. 80 HP because the impeller size makes it impossible to reach the RPM's where peak HP is?
Is the 288 cam a drop-in replacement or do I need the whole kit with timing gears&chain and all the other goodies?
And does the current camshaft need to come out of the engine to find out the specs?
My primary goal is to have a reliable and happy running engine which is durable, but I think there are some additional RPM's / speed 'hiding' somewhere. This boat (a Glastron-Carlson CV-23) was a 55 MPH boat with the stock Ford 460 and A impeller back in 1977 and I can reach only 51 MPH now.
I know I have a different impeller, but I have doubts if simply exchanging the impeller would be good to find the missing rpm's and mph's, so that is why I am questioning the way the motor is performing.
@Carlson-Jet
I tried to use the screen-name 'Carlson-Jet' myself, but found it 'occupied' . Funny to see you posting right away then :)

[DUECE'SDAD]

I may have missed it, but what kind and size of boat ? ?

[GCJ]

It's a 23 foot Glastron Carlson.

[bighead]

I have a smaller boat than you at 20'8" but it is a heavy open bow, motor is the Hardin Marine 325hp with the 80s era smog small port heads with a mallory dual point and 750 marine carb, it has a E pump with inducer, AA american turbine pump and stuffer, it turns 42-4300 rpm. Previously it had a Berk a imp in a otherwise tight pump it is now much better out of the hole and acceleration is better plus it can cruise at a much lower rpm than before, top speed suffered to the tune of 5 or so mph, top speed is 58 on GPS now, even though I want more speed I do not want to lose the out of hole and cruising performance. Just something to think about.

[CARLSON-JET]

GCJ, I guess I should have reported that the Agressor "A" is Close to the Berk "AA". If it were me I would get the parts list of your build dialed in a little better such as casting numbers on the heads, get a dial indicater to get a close spec on the cam even if just lift numbers. Bringing the combo closer together in terms of matching components can net noticeable gains. You have a heavy boat with alot of drag and that will be hard to overcome unless you really step up in power. Welcome to the boards. R.B.

[GCJ]

Thanks Bighead & Carlson-Jet.
The good holeshot and low cruising rpm are indeed important for me, so I don't get very excited by changing the impeller.
It looks like a good idea to wake the engine up a little, but before I start changing things I wanted to know if these rpm's are expected for what I have engine-wise and it looks like it.
I will research the parts I have now a bit better to start with.