delay in response 455 olds

[dgie]

Can anybody tell me what to look for in the cause behind when I am at a dead stop and mash on the gas pedal there is a delay before the engine responds?

[BrendellaJet]

maybe there is some slack in the cable?

[dgie]

slack in the cable, I never thought about that one before, how do you check for that?

[dgie]

wait,,, that can't be it, beacuse I get the same response when I have the cable off and work the throttle manualy.

[CrdStang]

It's a tuning issue, most likely carb.
First thing I'd do is check to make sure the accelerator pump is squirting a good stream of gas down the carb. Does the engine splutter at all during the delay?
What kind of carb do you have?

[Wally_Gator]

What carb are you running on it?
If you have a holy, check the power valve as well.
One backfire through the carb with ruin power vlalves.

[dgie]

It does not sputter I dont think, The carb is a Holley 46170 vac seconadries and manual choke.

[dgie]

I already changed the power valve and it is still doing it

[dgie]

and getting a good stream of fuel from accelerator pump

[Back Forty]

Well I would point towards the vac secondaries side of things to start. Is the diaphram healthy or hard?

[Floored]

I run a 3310-3 and use a 7.5 power valve which took a little delay out of response. set accel pump to hit as soon as you hit the throttle and switched to a brown secondary spring for a smooth transition. set initial timing around 10-12 deg. other than that hows the boat running?:confused:

[Moneypitt]

1st, vac secondaries have nothing to do with initial throttle response. Most likely you have a delay in the accelarator pump circuit. This can be caused by several things, from actual preload of the plunger assy, to a bad or dirty check ball in the acc pump chanel. To check the acc pump, with the engine of, repeat OFF, while looking down the carb, ever so slightly move the throttle linkage. Just the slightest movement should cause the squirter to squirt. If it doesn't, there is your delay....If after the first effort, a second effort does squirt, its your check ball/plunger, either in the bowl above the squirter, or in the circuit just under the nozzle. Additionally, a power valve will not cause a delay in initial throttle response, but will affect the power curve under a load as vacuum drops off and the main jets have not started to fully flow....Feel free to PM me with any other questions you may have after you test the acc pump action...........MP

[Foggerjet]

if you have a vacuum advance make sure the hose goes to ported vacuum and not manifold vacuum. If it's hooked to manifold vac the timing will retard sharply when the plates open and vacuum falls.
fog

[dgie]

Its good to hear from yall again, once again thanks for the help. It feels good to be back in the game. The boat is running really good. It seems like everytime I take it out Some chick comes up and starts telling me how much she likes the boat. They are kind of rare out here in Texas. I will check the accelerator pump this weekend if it doesn't rain. One more question I am still kind of chasing that deamon I think yall remember me telling about before where I am topping out at around 57 mph. Could this have anything to do with that? If not I will keep chasing it, but at the same time enjoy the boat and the chicks :D

[dgie]

Yep one side squirts the other just dribbles out, what now replace the accelerator pump, or? Also I am getting a misfire at around 4000 rpm’s foot all the way to the floor. My rpm's top out at around 4200 rpm’s when it starts to pop a little I let off. Could this be attributed to the accelerator pump or something else? On a side not I am suspecting the Jacuzzi pump is the reason I am only topping at 48 mph on GPS I think I should be around 60 to 65 mph. Does anyone have a berkley they want to part with cheap?

[CrdStang]

The popping at high RPM WOT sounds like it might be running lean. What size jets do you have on the secondary side?
What power valve? If I remember correctly, you want a power valve that's 2 numbers lower than your manifold vacuum at warm idle under load, so you'd have to check it with the boat in the water.
There are different size accelerator pumps, you can upgrade to the big pump, get the biggest pump cam, or both. The cams are in different colors, I don't remember the sequence though.
I think your secondaries could be a contributing factor. If you have too soft of a spring in there, they can flop open and over-carb the engine. If you "feel the secondaries opening", you have too soft of a spring, what you're really feeling is the engine catching up to the carb. You can get a quich change diaphram top and a spring assortment for pretty cheap, like <$20. It's fun to swap 'em around and see what works best.

[Floored]

Dgie, on my olds( with 3310-3 750) I went to 76's on primary side. when idleing in the water i had 10,5 in vacuum and use an 85 power valve. took out the part throttle hesitation when pulling skiers. bought the quick change secondary kit and with the brown spring you can flat foot out of the hole and no hesitation at all, or surge. make sure your squirter tip is clean on both sides and maybe change the accelerator pump diaphragm. you can check accel pump on work bench by filling primary side through the vent and hitting the throttle until it hits as soon as you move the throttle. make sure your fuel filters are clean, do you run a water seperator? those will lean you out if clogging. what intake are you using? where is your timing set at? don't be blaming that poor jacuzzi now, mine works purdy good:D and once you have your tune-up set then the speed will come up.. I went out 1 day with my tool box and an assortment of jets and power valves, vacuum guage and timing light and secondary spring kit and "worked" until I had it nailed. now its just gas and oil changes and fun:wink:

[dgie]

Here is an update. I took the boat out yesterday, before I did I cleaned the crap out of the jets and replaced the fuel filter as advised here. Well the boat performed really good. It does not hesitate as bad when I stomp on it and the engine performs much smoother overall especially when the secondaries kick in. There used to be a gap or delay just before they kicked in. Also before I could watch my fuel pressure guage that I mounted up by the carb go from 6 psi to 4.5 psi when I hit 4000 rpm's, now it stay pegged at 6 psi all the time. So the fuel filter may have had a bunch of crap in it. Also the popping stopped at max RPMs so I must have been leaning it out pretty bad. So all in all it was a pretty succesful day for me. Thanks for the help everyone. I am sure I will have more questions in the future for you all.