318 has developed a miss?

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169dart4y

169dart4y

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So I have a 318 that has about 25000 miles on it and runs good but I noticed the last few times I drove it seemed to have a miss and popped out the carb when I jump on it, only a few times. Now I noticed when in gear {automatic} stopped the alter gauge drops when the miss hit's. You can feel the miss and see it on the gauge.
Any thoughts on what would cause this or where to start?
Thanks
 
went was the last time you did a general tuneup?...new plugs...cap and rotor?

clean the carb....adjust the carb.....
 
70aarcuda said:
went was the last time you did a general tuneup?...new plugs...cap and rotor?

clean the carb....adjust the carb.....
Click to expand...
It's been about 6000 miles since I tuned up and installed the motor. Why would the alternator dip every time the miss hit's . Would a bad spark plug do this? I was thinking the cap and rotor, the wires all look good. I will have to pull some plugs and take a look.
 
Bad plug wire, cracked plug.....voltage leakin somewhere to ground where it ain't supposed to.
 
your describing a wire shorting out cracked coil ect ,to close to the exhaust system?
 
Run it at night in the dark, open the hood and check the spark plug wires for any arcing. It will be obvious in the dark...

You could also start it, then disconnect one plug wire at a time until you find one that doesn't affect how it runs, then check that plug and wire for any problems. Check the resistance on the wire to see if it is bad or spark plug.
 
krazykuda said:
Run it at night in the dark, open the hood and check the spark plug wires for any arcing. It will be obvious in the dark...
Click to expand...

That's a good idea to see if you have some spark jumping around. I would also suggest putting some water in a spray bottle and lightly mist the cap and wires when you do this.

Don't soak them, just a light mist.
 
By "alternator guage", do you mean the stock ammeter? If so, I assume it is flikcing towards the D side (discharge) when you have the miss?

After your tune-up checks: A spark around the distributor or spark plug wires would not likely cause the alternator output to drop, as the ballast and coil isolates the spark area from the car's power system. It is more likely the other way around: some erratic wiring issue is causing the voltage to the ignition systm to drop and cut out the ignition momentarily.

I would start with a voltmeter and attach it to several points at different time and monitor to see what it does when you get the miss; you would need an meter type of voltmeter not a digitial type, to be easy to read the fluctuations. I would 1st monitor the dark blue wire connection to the ballast resistor; this is your ignition power source when running and also feeds the voltage regulator. An erratic, faulty ignition switch would be detected by this.

Also, have you disconnected, and inspected the bulkead connctors?
 
Or the amps drop when the RPM's go lower from the miss.:)

Could be as simple as a fouling plug, but the pop out the carb would be something I would need to get to the bottom of.
Might have an intake valve hanging up and not closing intermittantly, or just a lack of fuel causing the pop back through the intake.

First thing I would do is pull the plugs and see if there is one that is significantly different than the other.
This would give you a starting point on which cylinder is acting up.
 
TrailBeast said:
Or the amps drop when the RPM's go lower from the miss.:)

Could be as simple as a fouling plug, but the pop out the carb would be something I would need to get to the bottom of.
Might have an intake valve hanging up and not closing intermittantly, or just a lack of fuel causing the pop back through the intake.

First thing I would do is pull the plugs and see if there is one that is significantly different than the other.
This would give you a starting point on which cylinder is acting up.
Click to expand...

^^^^ xx2
 
Actually, if you're gonna go there, it would take an exhaust valve staying closed to make a pop through the carburetor. If it was the intake valve, you wouldn't get a pop, because that cylinder would not fire. The pop is the exhaust coming back through the intake and out the carburetor IF a closed exhaust valve is what the problem is. I was tryin to be optimistic. lol
 
RustyRatRod said:
Actually, if you're gonna go there, it would take an exhaust valve staying closed to make a pop through the carburetor. If it was the intake valve, you wouldn't get a pop, because that cylinder would not fire. The pop is the exhaust coming back through the intake and out the carburetor IF a closed exhaust valve is what the problem is. I was tryin to be optimistic. lol
Click to expand...

I have to disagree with this.
If what you state is true, then why does a burned intake valve cause popping out the carb?
AND why does a lean condition cause popping out the carb, even if there isn't a burned or open valve (or closed ex valve)?

I already know the answers to the above questions, just wondering how you can say that.

OH NO, ALIENS GOT ROB!!! :toothy7:
That is the only explanation.
 
TrailBeast said:
I have to disagree with this.
If what you state is true, then why does a burned intake valve cause popping out the carb?
AND why does a lean condition cause popping out the carb, even if there isn't a burned or open valve (or closed ex valve)?

I already know the answers to the above questions, just wondering how you can say that.

OH NO, ALIENS GOT ROB!!! :toothy7:
That is the only explanation.
Click to expand...

It cannot. The popping out of the carburetor is the cylinder still firing. It cannot fire if the intake valve is burned, because that cylinder cannot build compression. However, if the exhaust valve is closed for whatever reason, bad lobe, bad lifter, bent pushrod, broken rocker, or a combination, the cylinder will still fire, but the exhaust will be routed back through the intake and out the carburetor. Disagree all you want, but that's how it works. I suppose if the intake valve is burned, it's possible to get a pop, but nothing like what I am talking about. when an exhaust valve is held closed through the exhaust stroke due to damage, the pop will be LOUD and rhythmic because it will be happening every single time that cylinder fires. You will not have a "skip" as defined by a dead cylinder, but it will run like hell, because exhaust is being routed where it does not belong.

I am not saying that's what his problem is. I am simply describing what happens when an exhaust valve doesn't open.
 
RustyRatRod said:
It cannot. The popping out of the carburetor is the cylinder still firing. It cannot fire if the intake valve is burned, because that cylinder cannot build compression. However, if the exhaust valve is closed for whatever reason, bad lobe, bad lifter, bent pushrod, broken rocker, or a combination, the cylinder will still fire, but the exhaust will be routed back through the intake and out the carburetor. Disagree all you want, but that's how it works. I suppose if the intake valve is burned, it's possible to get a pop, but nothing like what I am talking about. when an exhaust valve is held closed through the exhaust stroke due to damage, the pop will be LOUD and rhythmic because it will be happening every single time that cylinder fires. You will not have a "skip" as defined by a dead cylinder, but it will run like hell, because exhaust is being routed where it does not belong.

I am not saying that's what his problem is. I am simply describing what happens when an exhaust valve doesn't open.
Click to expand...

Your talking a backfire through the intake, and I thought we were talking about popping like a lean condition pop under a load.

Fuel burns weather it's under compression or not, just not near as sudden like when compressed.
So a burned intake valve can certainly cause intake popping, and a slow to close or hanging intake valve can do the same. (open or burned intake valve ignites the fuel in the intake when the plug fires)

A non opening exaust valve lets the burning fuel back into the intake doing pretty much the same thing, but with much more heat and pressure.

So I guess we don't know if it's pop or a POP! when the OP's car does it. :)
 
Bad Sport said:
Reversion?
Click to expand...

Yes. The cylinder is still firing, but since the exhaust valve cannot open, the exhaust routes back through the intake. I've seen it so many times when an exhaust cam lobe wipes I have lost count.
 
RustyRatRod said:
Yes. The cylinder is still firing, but since the exhaust valve cannot open, the exhaust routes back through the intake. I've seen it so many times when an exhaust cam lobe wipes I have lost count.
Click to expand...

Makes sense.
 
So I finally figured out what was causing the miss. It was a spark plug wire that I had not fully seated the wire on the tip of the plug and after a while{ quiet a few miles} it burned the end of the wire which was causing the miss.
Thanks for every ones input. :violent1:
 
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