Resistor spark plug converted into a non-resistor spark plug (with pictures) - PeachParts Mercedes-Benz Forum

lsmalley · #1 01-27-2014, 02:43 PM

Quote:

Originally Posted by RBYCC

Not sure why you would go through this effort as the non resistor plugs are still available. May cost a few dollars but you are assured of quality.

The fallacy in your modification is that you may read 0 ohms using the less then 9VDC provided by the multimeter.
you can use any type of metal, but all metals are not equally conductive.
Copper is the most common in non resistor plugs as the NGK BP5EFS, but the best conductor would be silver as in the hard to find Beru/Nology S1K Silverstone plugs

Impress a service voltage of 35KV + and you may find even the slightest gap between conductors can create an internal arc which will degrade the plug.

You can't compare a solid top to bottom electrode with the pieced together electrode you are creating.

Ed A.

This is a good point, I did not think about the degrading of the plug internally, but wouldn't also apply to the resistor as well? It is not a solid conductor and it too would be able to have a gap in between. On another note, the plug does have an internal spring which would make sure that there remains a solid connection between the conductors. I will pull the plugs in a few months to check the integrity of the components. Also, I do not understand what you mean about the fallacy in the modification using < 9VDC.

Quote:

Originally Posted by pawoSD

When I last needed plugs I too was able to source NGK non resistor's for my 420sel without a problem, only a few dollars each at O'reilley's.

I have tried oreilly's, as a matter of fact I was on the phone with them today and they said they do not stock them, nor does pep boys, nor does autozone. They all cross referenced to a resistor. My location is Palm Springs and there are plenty of older and newer model MBs on the road. When I go to the junk yard I usually make it a habit to go and pull one of the plugs in the MBs there and I have yet to pull one where there was a non-resistor plug in it.

JamesDean · #2 01-27-2014, 04:17 PM

Quote:

Originally Posted by lsmalley

This is a good point, I did not think about the degrading of the plug internally, but wouldn't also apply to the resistor as well? It is not a solid conductor and it too would be able to have a gap in between. On another note, the plug does have an internal spring which would make sure that there remains a solid connection between the conductors. I will pull the plugs in a few months to check the integrity of the components. Also, I do not understand what you mean about the fallacy in the modification using < 9VDC.

You would be surprised at the effect of contact area. Your copper replacement slugs might not be as smooth as the resistor's contact area. or maybe it its better, I'm not sure.

The voltage that passes through that area, normally, is between 20 and 30 kV, with a 5K resistor that's about 4+ amps of current. With the 9V that the volt meter can supply you only get 0.18mA. A fraction of how much current will actually flow through there. That will have an effect on your measurement to some degree.

Quote:

I have tried oreilly's, as a matter of fact I was on the phone with them today and they said they do not stock them, nor does pep boys, nor does autozone. They all cross referenced to a resistor. My location is Palm Springs and there are plenty of older and newer model MBs on the road. When I go to the junk yard I usually make it a habit to go and pull one of the plugs in the MBs there and I have yet to pull one where there was a non-resistor plug in it.

To be honest, I've not been able to buy the plugs for my m103's locally. I have been able to buy the plugs for the m116/m117 locally.

pmckechnie · #3 01-27-2014, 07:09 PM

I was just checking around and found NGK BP5ES-11 plugs at Advance Auto. It says they are nickel and no resistor. Nickel is a good conductor. Would they be a good replacment for the copper core plugs?

Paul