You gained 76 cubic inches and are probably making more power. You need to tune the chassis.

Get some video of the tires. Bet you it's beating the hell out of the tire.

Take a piece of soft fuel line that will fit snugly over the vent tube sticking up in the front of your carb squirters and route it back towards the rear of the carbs so if any fuel sloshes up into the fuel bowl vent it won't spray or spew into the carb.
Your probably okay with those stock white vent tubes on the metering blocks though
You need jet extensions in the rear
Are you spraying the NOS?

As said get some jet extensions

Put a piece of rubber hose in a high arch between front and rear bowl vents. Cut a notch out at the top of the arch. You can zip tie it to the air cleaner stud to secure it. And jet extensions on the secondary jets.

And I still feel there is something else going on in the suspension. The increase in torque from the new motor is causing rear suspension issues.

Looks to me like the shocks could be topping out, pulling the tires off the track.

Yes Everything the same except engine from 496 to 572 with new camshaft and torque converter from 5500 on 496 to 5000 on 572 , the rest is the same , also change the headers with 496 was 2" , now is 2 1/8 same brand TTI ceramic

ohh i see this in some car at mopar nats OHIO , need connect the two hose of bowl vent and make a hole ??

Yep 400 shot of nitrous !

Chassis have Dana 60 , caltracs , monoleaf , connecting frame , double adj qa1 shock , never problem in many years , hook very good 1.40 60 ft with 3900 lb

At this point the cause of surging could be :

1) fuel issue but yesterday i have checked filters pump all hose and carb , no restriction

2) fuel jet extension ?

3) fuel pressure is at 7 psi , is better at 9 psi ?

4) carburetor too small ? from calculator 572x7500 / 3456 would be 1250cfm , i have 1050 .. can cause this surging ???

4) rear tires unloading ? shock ? mmmmmm very strange

5) tight converter ? is 5000 RPM

I have never heard that a to small carb. will make the motor surge
They usually will run better with a bigger carb
Surging, running out of fuel, and hopping are two completely different issues Figuring out what the car is doing is the key to fixing it
I would try and have someone video a run from the side at a 90 degree angle on the starting line as close as they can get to see what the chassis is doing the first 50 to 100 Ft.

As mentioned, put two jet extensions for the rear jets.

https://www.summitracing.com/int/search/...et%20Extensions

Guys ... i zoommed the video from inside and found the problem...at launch the fuel pressure gauge drop from 8 to 2-3 Psi ..the safety switch of fuel line of nitrous when go down switch off the nitrous ... this up and down ... cyclyc ... , i think this is caused from bad pump A2000 ? low tank vwnt ? i have factory tank with big 5/8" tank sender ... i think is time of Fuel Cell ...

OK but you still need the Jet extensions for rear bowl
Im sure 1250 would work better on your engine.

yes Sure !! how many HP more with 1250 ???

my Pump A2000 Flow is 350 GPH , this is good for 900 HP +400 of nitrous ?? i see when fogger is actived the pressure go down from 8 to 3 PSI , i dont know is is only caused from tank or also from opening fuel solenoids

8-9 psi fuel pressure is higher than necessary, but dropping to 2-3 psi will cause a problem. You need constant pressure going down the track. The rubber tube will make sure that you aren't pulling fuel out of the vents and dumping it into the venturi's. The jet extensions will make sure that the secondary jets stay covered with fuel. Putting a bigger carb on will probably help make more power, but will not change anything with the surging.

I would be surprised if it is that. you could shut your fuel pump off at the line and still have enough fuel in bowl to make it threw first gear. If you have qa1 shocks in back I doubt they have enough valving to control caltrac.

yes drop at 2-3 psi ..understand the problem of bowl ...but also the stock tank can cause this ??