carb pops when you get on the gas hard

[jbuenojr]

I have a 1974 Rogers jet
With a Berkeley jet 12jc
1973 454 Chevy ls6 , speed demon carb 750 cfm 4 barrel double pumper, with a victor 2-r manifold, with rv cam, steel crank, hp heads
Its has msd 6l Ignition box, pro billet distionor, 8.8 wires,
Gap on my plugs is .o6
I need some help with setting up the carb.
I am running my motor around 140 -150 deg
My timing is 8 deg
When I get on the gas the carb starts to pop?
WhatÂ’s going on? Never did that with my old carb.( old carb was leaking a lot
Is my timing off? Or maybe a vacuum leak some where?
Is there some that help me out?
Thanks
johnny

[Beer-30]

It's lean. A "back-pop" is a lean condition.
Either the accelerator pump is not doing it's job, or you have a vac leak.

[enzo]

your timing is retarded - add some timing - what's your advance curve if any, you should be at 34 degrees BTDC at full advance

[SmokinLowriderSS]

I've run 8* on a 454 for a couple decades absolutely flawlessly, so that isn't bad, but I would bump it to 10*, maybe as far as 12 depe4nding on the total advance curve, aiming for 34* to 36*.
Lean pop is correct IMO, most likely.
Double check your idle mixtures (since you are there), and make sure your accel pump is working.
With it idling, take either a can of WD-40 OR a can of startign fluid (less messy) and squirt small ammounts arround al the gasket areas in search of a vacumme leak. Any leak sucking in the sprays will change the idle immediately, for a few secconds.
Does it do it from a mild roll on the throttle, or just if you stab it pretty good?
What happens if you flat-foot it from idle to the floor?

[GasGuzzler]

What is the plug gap???

[jbuenojr]

when i stab on hard from idle to full it pops.. i try the vac leak test, them check my timing i dont think i am at 34* @ full advance.. , also check my accel pump ... thanks for the helpI've run 8* on a 454 for a couple decades absolutely flawlessly, so that isn't bad, but I would bump it to 10*, maybe as far as 12 depe4nding on the total advance curve, aiming for 34* to 36*.
Lean pop is correct IMO, most likely.
Double check your idle mixtures (since you are there), and make sure your accel pump is working.
With it idling, take either a can of WD-40 OR a can of startign fluid (less messy) and squirt small ammounts arround al the gasket areas in search of a vacumme leak. Any leak sucking in the sprays will change the idle immediately, for a few secconds.
Does it do it from a mild roll on the throttle, or just if you stab it pretty good?
What happens if you flat-foot it from idle to the floor?

[OverKill]

You most deffinatley should be no less than 32* of timing. Also do you have J-tubes in your Carb.? Try running a little higher octane in your fuel. Oh and if you have those small fuel filtter inserts in your carb. (the round glittery ones). Take them out and use a fuel filter system with a water seperator. Let us know how it turns out for you.
OverKill