Ok.. so I've done a 305-350 engine swap on my car.. I too have the engine idle surges that are so talked about.. I must find how to remedy this..
The problem is now if I mash the gas (it wasn't like this before) the car doesn't go. The engine screams, but the car just piddles. It's a Caprice 350 (l05) If I don't mash the gas and give it a fair amount I can accel faster than I can if I mash it.
I used to be able to spin tires at a stop just by hitting the gas, can't do that anymore.. infact I was outrun by a toyota corolla (monsterous vehicle... not really) about a month ago.
Any guesses?

 

I have the idle surge problem, but that's b/c I need to turn up the fuel pressure. I haven't gotten it quite tuned right since the motor was rebuilt (ported heads, bigger cam). I'm intrested to hear is anyone has any ideas why it's slow off the line. My truck felt a lot quicker off the line before the rebuild, but I didn't drive it for about 6 months so I can't quite remember.

 

The reason it falls on it's face at WOT could just be an innacurate tune. At part throttle, the computer compensates for innacurate mixtures, but at WOT the computer just goes by a set table for how much gas to add, and ignores the Oxygen sensor. Time to start logging data, burning chips and/or messing with fuel pressure.

Good Luck

 

My guess would be the computer if you have changed the chip yet. AT WOT the computer changes your timeing and a whole bunch of other crap .If you still have the 305 chip the computer is tuning everything funny because you have a different engine .I would say you need a chip out of a 350 car.

 

Could be your fuel pump as well. The stock one can barely feed the LO3. It's probably a combination of you chip and fp.

 

bad fuel pump woudl be my very first guess. Get a gauge and see what it is at WOT. The fuel pressure is probably hitting the skids at high engine loads.

 

cool I'll check the fuel pump.
The chip is custom burnt for an original 305 camaro that put the (l05) cop caprice engine switch.
So I don't think the chip is my problem.. I'll hook up my comp thingy and take a look at the fuel pressures..
Thanks
-Justin

 

did you change the injectors?

 

i cant remeber where but someone told me the things you should do is check the fuel pressure ,get 255 walbro pump,electric fuel pressure gauge mounted in side of the car and oxygen sensor gauge in side the car,and a vafpr for the 350 its alot better than the ghetto made regulator.

 

The way I check my fuel pressure under load:
Purchased TBI Fuel pressure testing kit from Auto Zone.
Routed hose under the back of the hood and taped it to the windshield (very securely mind you)
Drove camaro and watched as the pressure dropped from 16psi to 9psi under any load.
Installed the Walbro 255 pump
Pressure was set to 22psi-watched it drop to 10psi under load.
Got pissed-pondered driving the 'maro off of a cliff.
Took the pump out and we noticed a small rubber hose going from the sending unit to the pump had ruptered.
Replaced the hose with a new piece and braided sleeve.
Watched the fp remain at a steady 21-22psi under load.
Moral of the story-you will more than likely need a new fuel pump. When you replace it, replace the rubber hose and slip some braiding over it for extra strength. I think my fp test kit was $40 or so, and the fuel pump was right around $100.

 

could be your torque converter. if the needle bearings went bad the converter won't grab and transfer power properly.

 

well I found out some news.. I still know my tranny is messed up but that's going to be fixed on tuesday (under warranty).
Yesterday night though, I found out that my headers melted my spark plug wires, and my fuel pressure regulator is all messed up and dumping far too much gas into the engine..
As for the tranny, I'm sure something is slipping. I'm positive of that...

 

Running a 350 now you are going to need more fuel and air. The stock chip or the one you have is fine. The stock fuel pump has a low volume rate you probably need to change to a high volume TBI pump. And your stock injectors are probably flowing too little.
If you havn't done the ultimate tbi, do it or visit www.turbocity.com. They have matched injectors, high volume TBI pumps and Excellent modified 454 throttle bodies. You can email me with any other questions I will be more than happy to help.

 

You are right about the fuel pump and injectors. But the stock chip is NOT ok if that is what he is running. He needs one from an LO5. And if worse comes to worse, he can always increase the fuel pressure to compensate for the smaller injectors, though he will indeed need a new pump to do that.

 

Betcha a dollar it's the converter

 

my 91 does that and its basicly stock. in fact you can smell mine out of the engine compartment!
oh yeah, sorry about the corrola dude,bummer.