poping out the exhaust

[generaljmwlee]

I got the motor started this weekend! Idles great and has good throtle responce. but at Idle it runs rich and has a pop out the exhaust once and a while.and when motor gets under load (trying to back it into the garage)it continues to pop worse. it has a edlebrock 1406 carb . could it be because I just have the pcv just sitting in the hole with no gromit or I dont have the exhaust clamped tight? I think its carb prob but not sure

 

[Big John]

If its poping in the exhaust, its too lean.

If the PCV isn't sealed to the valve cover, I would say you've got a potential vacuum leak right there and that will lean it out.

 

[generaljmwlee]

the pvc is just sitting with no grommit, and the ehxaust burns your eyes in the garage

 

[moparchris]

the pvc is just sitting with no grommit, and the ehxaust burns your eyes in the garage

There are many different gases that make up exhaust emissions. The two that we worry about are HC (hydrocarbon) and CO (carbon monoxide). HC is unburnt fuel in the exhaust. CO is partially burnt fuel. Co is a odorless gas where HC is very pungent and will make your eyes water. If a motor is lean then you will get HC in the exhaust due to one or more of the cylinders misfiring because of lack of fuel. Conversely it can also emit HCs when it is too rich and the A/F ratio is too far off and the cylinder misfires. The PCV valve is a minor leak at best and most carbs are calibrated for this out of the box. I would check the basics first. First do a visual check to make sure all the plug wires are plugged in correctly and that none of the plug gaps are closed. Then, fire the motor up and pull off plug wires one by one and see if one cylinder is not running. I do this by pulling out the plug wire from the cap (motor off) and putting a 2 inch piece of vacuum tubing into the cap and then plug the plug wire into it, do this with all eight. With the motor running use a ground wire to ground each cylinder one by one and se if it drops RPM. If you have a big cam you may have to idle up the motor to see the effects. Let us know how that works.

 

[droptop]

Check your firing order.

 

[A31PKG]

...Idles great and has good throtle responce....[/quote

I agree with what's been suggested...However, if it idles great & has good throttle response but backfires under load, I would also look at the valvetrain...I have seen countless times over the years, where a broken valve spring or a lifter with a hole in the base would cause exactly what you describe... If both of those two possibilities are negative, then I would do a cylinder leak-down to see if any of the valves are not sealing properly... Of course, there are many ways in which an engine can backfire... Firing order, ignition timing, valve timing, induction problems, etc etc....

 

[generaljmwlee]

poping is gone and was able to get electronic dist to work ! air gap on dist was set at .035 from new and all the parts store said the same thing. needed to be .008 set it and fired right up. pulled all plugs after it cooled and cleaned, regapped them, double checked firing order and pop is gone !thanks to every one who answered .will post video soon as I can.

 

[droptop]

:banana: :banana: :banana:

 

[A31PKG]

Awesome....include a smokey burnout....

 

[generaljmwlee]

the smokey burn out will have to wait till I find the throtle cable and the gas pedal its like those darn gremblins were at it again! :brickwall: