I have a 350 from a 74 caprice in my camaro, with a 4 barrel Holley, looks like a 650. I had it rebuilt recently and I've had a few different people look at it to make adjustments. When I floor it, it picks up plenty of power, but it will cut out hard for a second. It's not as bad at high rpm. It almost acts like a fuel filter issue, but it's got a new clean one on it. It also seems to run a little rich. I know my choke is messed up a little also. Does anyone know what might be wrong?

If it cuts out like stops for a second and comes back i would check the timing 1st...make sure the timing is correct.

That's exactly what it does. It's just when it's wide open throttle. It'll keep cutting out while its wide open too

I'll take a look at the timing and report back probably tommorow.

Huh...id check timing...

Pull a plug or two...see if they look good...and not dripping gas.

May be running really rich..wrong jets or bad power valve...

Or...may be a valve issue or ignition...but start on easy stuff
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Has brand new plugs... Definitely needs wires though. I'll change them this weekend

Sounds more like an accelerator pump issue, or secondary bog.

Get the "LIST" number off of the front of the choke tower and let us know what it is.

Sorry to leave everyone hanging, I've been crazy busy. I'll get that number as soon as I can get to it. Tonight I ran some octane booster and 89 octane fuel and it ran a lot better, there was only once it acted up, and when it did it did it bad. I changed fuel filters and it had a good bit of pressure when I took the old one off. It also had some bubbles come in to the filter when I undid the hose clamp and took the filter off. I'm thinking vaporlocked?

How much pressure build up should it get at the carb? When I undo the hose it sprays everywhere, I'm wondering if the people who v8 swapped it still have the electric fuel pump hooked up. I never hear it run but I haven't listened for it really.

You shouldn't have more than 6.5 PSI at the carb. If the car was originally a LG4 then there wasn't a pump in the tank in 1985. The fuel pump is mechanical on the passenger side towards the front of the block. If the pump is an original (85 LG4) return style mechanical pump make sure the return is hooked up and not blocked off. IF it's the older style mechanical pump it might not have a return and that is okay.

With having a problem as soon as you press the pedal you could have the throttle blades positioned wrong. There is a slit on the side of the throttle body called a idle transfer slot. There shouldn't be more than 0.040" exposed below the throttle blades. Much more than this will cause a bog.

Also make sure your accelerator pump is set properly. Open you throttle all the way and hold it open. then Press the pump diaphragm cover’s arm up till it stops. The gap between this and the pump operating lever adjustment screw should be around 0.015 to 0.025" This makes sure that the levers have good contact and there isn't any delay with the accerator pump.

I agree with 86. Sounds like the timing is to advanced. Be careful with the octane booster. To much is not good for your engine.