problem with popping through carb on half or full throttle, runs fine when driving normal stop and go... originally had a 2 barrel and intake, switched to 4 barrel and intake, changed timing gears and chain, changed the hole distributor, changed fuel pump and filters, blew out the gas lines, changed plugs and wires. I'm at witts end trying to find the problem, It was doing this when I had the 2 barrel on it. So I thought I would go with a different setup, same issues... It runs great when you baby it...
Any ideas will help

 

Ok, let's see about diagnosing and narrowing down what system(s) may be causing the symptom you're describing. The most common cause for what you're describing is a vacuum leak.
How many miles on the engine?
Is the engine stock or has some inept wrench turner monkeyed with it? In other words, does it still have all the emission stuff on it and is it all properly connected?
If you don't have a service (shop) manual for this car, get one.
Please note that just because something "looks" good doesn't mean that it is good. With that said, get yourself a vacuum gauge and measure the manifold vacuum. Assuming your setup is still, essentially stock, the vacuum at idle should be greater than 16" and steady. If not, you likely have a vacuum leak. You'll need to use a handheld vacuum pump with a gauge to isolate where the vacuum leak may be.

Get started and keep us updated on your progress.

 

I will get started on that soon, don't know when but soon.
Thanks for the input

 

okay the miles on the car is 96k original miles, I put a 4 barrel edelbrock intake, carb and a new hei. thinking that was the issue. Still does it after changing everything.... Vacuum wiggles from 18-20 not steady...

 

the car sat a long time before I got it, when I changed the plugs there was a lot on carbon built up on almost all of them. So I change them ( no luck ), so cleaned the 2 barrel carb ( no luck ), took timing cover off chain was loose but not terrible changed it any way ( no luck ), that's when I said heck with it I'll change the intake, carb and hei Still does it!!!! I'm thinking it might be valves are not seating all the way or the springs are weak or both. I don't hear no vacuum leaks but it is possible.

 

From what you described and the vacuum reading at idle, it sounds like the long block is all stock other than the timing chain you replaced.
I take it you double (or even triple) checked firing order. Since your description is stock engine, be sure the ignition timing is set to stock (I think is 6° BTDC at idle without vac. advance).
What about all the emission stuff? Does it still have the EGR valve, carbon canister, vac. adv. temperature switch, air cleaner heater valve, etc.? Don't discount your other accessories such as AC and cruise control if you have them.
I don't completely agree with your thought on the valves. You see, if the intake valves don't seat completely, the vacuum reading at curb idle would be less than 18". To help rule that out, do a compression test on each cylinder and compare the readings.
The valves and seats could be dirty. a cheap and easy thing to do is pour a couple of cans of fuel system cleaner or intake valve cleaner into the tank and drive it for a couple-hundred miles. There's also a fuel additive that helps decarbonize the combustion chamber.
Another thing you could do is pull off the valve covers and visually inspect the springs. If the engine had ever overheated or run hot for extended periods, the valve springs could loose their temper which could weaken them and even cause them to break. Chevy used two springs for each valve just in case one breaks, the other one keeps the valve from dropping into the cylinder.

 

OKAY !!! compression text results....
#1 155
#3 155
#5 155
#7 160
#2 160
#4 160
#6 160
#8 160
give or take 1 or 2 pounds...
redid all vacuum hoses...
reset timing...
NO DIFFERENCE !!!
I will try valve cleaner later...
I still think valves are carboned up along with weak springs...

 

Did you use a hand held vacuum pump to test the transmission vacuum modulator, distributor vacuum advanced, carburetor dashpot, EGR valve, A.I.R. diverted valve, heater valve, etc.?

 

No, but I will try it...

 

Don't neglect checking the power brake booster.

I was thinking about how you said the spark plugs were carbonized. You may want to check the exhaust heat riser valve. If it's stuck open, the engine would need significantly more time to fully warm up.