TheSamba.com :: View topic - What does popping sound after spark plug change mean?

Sun Mar 31, 2013 2:39 pm

Hey guys. I changed my spark plugs, wires, distributor cap and rotor today. I'm positive the wires are in the right spot...I took them off one at a time as recommended. When I removed the plugs they seemed to have a really large gap. They were all around .040. I gapped the new plugs at .025 as my hanes manual recommended. When I started the car up afterwards it seems to be idling slower and a bit rougher than before and I hear an intermittent popping sound. What does this mean?

Sun Mar 31, 2013 2:41 pm

Sounds like you accidentally changed the timing.

Max

Sun Mar 31, 2013 2:42 pm

I didn't loosen the distributor so is that possible?

Sun Mar 31, 2013 2:51 pm

Not unheard of for a distorted clamp to slip. And you were working in the area.

Just check the timing.

Max

Sun Mar 31, 2013 3:31 pm

Okay I adjusted the timing but it's still popping.

Should have set the plug gap wider like the old plugs? Could it be a wire issue?

Sun Mar 31, 2013 3:33 pm

Is it popping out the carb or exhaust, besides the popping, is it running rough.

Sound like you swapped a couple of leads,

Sun Mar 31, 2013 3:34 pm

sounds like its popping out exhaust and yes it is running rough.

Sun Mar 31, 2013 3:35 pm

buggyjj wrote: Okay I adjusted the timing but it's still popping.

Should have set the plug gap wider like the old plugs? Could it be a wire issue? you didnt gap your plugs to spec?

Sun Mar 31, 2013 3:38 pm

I did gap them to spec...I'm saying that the ones I took out had a much wider gap than spec.

Sun Mar 31, 2013 3:39 pm

I just triple checked the wires and they are in the right places.

Sun Mar 31, 2013 3:57 pm

The popping out the exhaust can be caused by a few things, fuel in the exhaust ignited etc etc. firing while the exhaust valve is open.
But if it was all good before you changed the plugs, then it really can only be two things, plugs or leads.

Because its running rough and popping out the exhaust, it has to be the leads.

Did you take them of the Dissy or just the plugs, if you just took the leads of the plugs, try this.

Swap the leads on one side then start, if worse, put them back they way they were. Then swap the leads on the other side, if worse then put back on.

If that didnt do anything pull your plugs, but my bet is your firing order is out.

Sun Mar 31, 2013 4:33 pm

Trevore wrote: The popping out the exhaust can be caused by a few things, fuel in the exhaust ignited etc etc. firing while the exhaust valve is open.
But if it was all good before you changed the plugs, then it really can only be two things, plugs or leads.

Because its running rough and popping out the exhaust, it has to be the leads.

Did you take them of the Dissy or just the plugs, if you just took the leads of the plugs, try this.

Swap the leads on one side then start, if worse, put them back they way they were. Then swap the leads on the other side, if worse then put back on.

If that didnt do anything pull your plugs, but my bet is your firing order is out.

Don't experiment with your firing order. Just follow procedure and set the firing order to the correct sequence. Its a lot easier than randomly moving wires around until you get it right by accident.

Sun Mar 31, 2013 4:42 pm

Sounds like there's a problem with one of the leads.

Tim

Sun Mar 31, 2013 7:04 pm

Sounds like you have the wires on correctly, but perhaps an end came loose? Grab each of the cables on the sparkplug end one at a time and try to screw the end in tighter if it will go.
Ray

Mon Apr 01, 2013 7:08 am

buggyjj wrote: Hey guys. I changed my spark plugs, wires, distributor cap and rotor today. I'm positive the wires are in the right spot...I took them off one at a time as recommended. When I removed the plugs they seemed to have a really large gap. They were all around .040. I gapped the new plugs at .025 as my hanes manual recommended. When I started the car up afterwards it seems to be idling slower and a bit rougher than before and I hear an intermittent popping sound. What does this mean?
I just did my plugs (73 Super) and the Bentley said to set the gap to 0.30 (I think)
Also, when I put my new wires on, I made a mistake and pushed the boot all the way to the end before plugging it into the dist cap. I had to take the wires off, slide the boot up a bit, and then plug them back in and slide the boot down.
I dont know if that helps.

Mon Apr 01, 2013 7:15 pm

Thanks for your help. I triple checked all the wires and I'm certain they are full pushed onto the plugs and the distributor cap. Still hear the popping noise although it might have started running a bit smoother. Perhaps I should widen the gap on the plugs? I put them at .025 as my hanes manual stated.

Mon Apr 01, 2013 7:39 pm

You have too much unburned gas going out the exhaust. Either a plug is not firing or your timing is off. Did you try putting back your old plug wires and the cap to see if theres a problem with new parts. When all else fails always use process of elimination. Works every time.

Tue Apr 02, 2013 6:39 am

Yehan73 wrote: You have too much unburned gas going out the exhaust. Either a plug is not firing or your timing is off. Did you try putting back your old plug wires and the cap to see if theres a problem with new parts. When all else fails always use process of elimination. Works every time.
Thats true. Brand new parts can fail sometimes.
1: Start the car and let it warm up
2: One by one, remove a plug wire (from the dist if easier) and see if there is a change. You have a 1 in 4 chance of getting this right
3: If you remove a wire and there is NO CHANGE, you have narrowed down the problem.

Tue Apr 02, 2013 8:57 am

You didn't mention changing the points, but have you checked your dwell.

Deezal

Tue Apr 02, 2013 9:20 am

I switched over to electronic ignition.