Popping from carburetor

[Chrisman]

Hello hoping to get some insight as to why my carburetor is popping on any kind of acceleration. The things I’ve done so far have been a compression test which was ok all cylinders had between 115-120 psi although motor was cold, replaced original quadrajet with edelbrock 650 Cfm av2 unit, checked timing which was set to 12 degrees advanced I Retarded it to 8 to the same result of nothing, changed coil and spark plugs along with wires. I also noted that there was only 4v to the coil when the car was running which seems low and yes the coil does have a ballast resistor but it still seems low to me. Distributor points were adjusted 5000 miles ago and dwell is 33 degrees which is not far from the 30 spec it says on my car. Cap and rotor were replaced 5000 miles ago as well. It is important to note that the issues started after I was driving with my coil wire unplugged and there was a about a 1 inch arc from the coil to the wire. After that there was a slight pop which only got worse. The engine is a stock 455 with the exception of the parts I described previously.

 

[melsg5]

You are getting the low voltage reading because you are using an external coil. If you look closely at the wires connected to the coil you will see the end with a horseshoe type spade has two wires. One of those wires is the Resistance wire and therefore an external coil is not needed. You should reinstall the Quadrajet, when properly setup it is far better than the Edelbrock. Did you carefully look at the cap and rotor for cracks? Did you look at the points for signs of burning? When you changed the points did you change the condenser? Condenser may have been damaged from the arching.

 

[Chrisman]

You are getting the low voltage reading because you are using an external coil. If you look closely at the wires connected to the coil you will see the end with a horseshoe type spade has two wires. One of those wires is the Resistance wire and therefore an external coil is not needed. You should reinstall the Quadrajet, when properly setup it is far better than the Edelbrock. Did you carefully look at the cap and rotor for cracks? Did you look at the points for signs of burning? When you changed the points did you change the condenser? Condenser may have been damaged from the arching.

thanks for the help I’m gonna look under the dizzy cap to see if it’s cracked or burned, condenser was not changed so I’ll take a look at that, had a mechanic told me it might be something internal like a worn camshaft but can’t hurt to see if it’s something ignition related. Funny thing I originally thought my ignition capicitor was a ballast resistor. Where is the resistor on a car like a grandville? Also how much voltage should I get at the coil?

 

[melsg5]

thanks for the help I’m gonna look under the dizzy cap to see if it’s cracked or burned, condenser was not changed so I’ll take a look at that, had a mechanic told me it might be something internal like a worn camshaft but can’t hurt to see if it’s something ignition related. Funny thing I originally thought my ignition capicitor was a ballast resistor. Where is the resistor on a car like a grandville?

Read my earlier explanation, double wire connection at coil positive terminal. When cranking a full 12 volts go to coil from starter solenoid R terminal. Once engine runs you get 9 volts from ignition switch due to the use of a Resistor Wire, no ballast resistor is used. If camshaft why good compression?

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[Chrisman]

Read my earlier explanation, double wire connection at coil positive terminal. When cranking a full 12 volts go to coil from starter solenoid R terminal. Once engine runs you get 9 volts from ignition switch due to the use of a Resistor Wire, no ballast resistor is used. If camshaft why good compression?

Ok I understand now and I had the same thought process about the camshaft so it’s on the bottom of my list of suspects. Thanks when I get the car back from the shop im gonna see what I can do about the voltage at coil and do some test on condensor. Appreciate the help

 

[melsg5]

Ok I understand now and I had the same thought process about the camshaft so it’s on the bottom of my list of suspects. Thanks when I get the car back from the shop im gonna see what I can do about the voltage at coil and do some test on condensor. Appreciate the help

Condensers are cheap, replace it, and to be clear the one inside the distributor cap.