No power out of ideas

[77cruiser]

Did you degree the cam by ICL or opening & closing numbers? It can make several degrees difference.

[Tahoe540]

I degreed with ICL then just checked the valve timing for verification

[motormonkey]

Verify timing on balancer, check that valves aren't to tight, check valve to piston clearence, check valve springs, try different ignition ( coil, box, plugs, wires) check carb is opening all the way and check jetting not to rich.

[dannobee]

Have you checked fuel pressure under load? How about the volume? It'll need close to a gallon a minute just to make 600 hp.

I mean, come on, it's got a hundred more cubic inches than the other engine, that should count for something.

[JoePorting]

"Hard to start" makes me think it's some kind of electrical issue. Do you have enough ground wires? Is it making 14 volts when running? Is the battery old? Old batteries with a short can draw down the electrical system.

[canuc]

ya fuel , spark or exhaust . Agree with the guys that have said spark , with what you have changed out also thinking primary voltage some bad wiring from key , grounds or battery . hope you find it soon . curious as to what impeller and what will it turn ? another thing I've seen is exhaust hose coming apart and blocking up in a muffler .

[mag2555]

The Cam needs for a motor 100 cid bigger then the 454 you where running is substantial!

Your feeding a motor that's 19% larger then what you had so if your fuel supply volume was on the edge of passing for 454 cid your in the red now!

[gmrocket]

Is the jet pump and hull verified as good?

Did the boat have good speed with the previous engine?

You have said what style of boat and it’s previous known performance

[GRTfast]

Ignition timing sounds too retarded. I’d say 18 initial, 38 all in by 2500-2800 range.

[englertracing]

Don't know anything about boats
Can you run wideband sensors?
They will tell you if your running out of fuel or if your ignition is missing.

[Tahoe540]

The boat ran fine with no issues on a rebuild of my jet with upgraded parts. Running an A impellar
Batteries are brand new Costco marine
I agree with everyone it needs more timing. I have always had locked out distributors. I do have the part to lock this one out.
I have bypassed the oil separator. I hope the water separator was choking it. Will test it Saturday.
You really can't run sensors on jacketed exhaust. Mine are cast too.
Fuel pressure was 6-7 under load

[rustbucket79]

I would like to bring up dynoing this engine to prove the engine is healthy.

That being said, let’s itemize what we know:

Several ignitions tried, no change
Fuel pressure (at carb inlet I assume) 7 psi running, no problems there
454 ran fine with current jet, fuel system, charging system, and exhaust system
555 is a turd with said setup

So clarify for me:
What rpm would the 454 achieve wide open?
What rpm will the 555 achieve wide open?
What do the plugs look like after a few minutes run time?
Are you running similar total ignition timing to what the 555 used in the other boat?
What cruise and wide open rpm did the 555 operate at in the other boat.
What exhaust in the old boat?
No other restrictions like carb not fully opening, restrictive flame arrestor, etc?
Have you done a compression test? Is it similar numbers to the old 555 in the old boat?

I would think a healthy 555 should turn an A impeller in the 5000 to 5500 range, even with log manifolds, unless it’s really down on torque in the bottom and mid range. (Low compression tunnel ram open class camshaft setup, requiring a B or C impeller)


The slow cranking has me wondering, check the crank end play in boat, possibly the mounts are misaligned on the new engine, and the jet drive is pushing on the back of the crank.

[Racing68]

We did a 572 for an airboat one time where the guy used a standard flame arrestor. Dyno showed good power and afr. Put on the arrestor and the thing went stupid lean like 17:1 lean. Put on a K&N marine approved air cleaner and went back to normal even picked up a few HP.

[FC-Pilot]

Tahoe540, I am looking forward to hearing how it goes this weekend. Good luck.

Paul

[Tahoe540]

Update, Boat runs good and starts fine but hits a wall at 4800rpm

I locked out the distributor and timed it at 36. It sounds so much better at idle and runs pretty good. I will only use locked out distributor from here on out as I don't build anything stock. Thanks to everyone that suggested that it was a timing issue.

I think a lot of you are right about the fuel system too. The boat currently has 3/8 line for the whole system and was fine for the stock 454 with a 600cfm holley. I doubt that same system would feed my 555 with a 1050. I did bypass the water separator and it made no difference with 3/8 hose. The fuel pressure is around 6.5-7 psi and the needle doesn't really move at idle. At full throttle or even running over 2500 rpm the needle bounces so fast I can only ready between 5.5 and 8 psi. The gauge is on the fuel log. One other thing I saw through the site plug was the gas in the front float bowl had a lot of bubbles or foaming. Only on the front one. Exposed motor and 160 water temp it was not getting hot.

My plan is to use a Tee to combine both tanks with the 3/8 hose to a 1/2 inch feed line to the pump and then to the carb with an 8AN carb fuel log. I have a 130gph mechanical pump that should be able to feed the motor. I want to try this before I pull the tanks for 1/2 inch pickups.

Any have any other ideas to test