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Old 04-22-2003, 01:02 PM
Duke2.6 Duke2.6 is offline
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Join Date: Mar 2003
Location: Southern California
Posts: 2,055
Multiple ground electrode spark plugs are a gimmick! A smaller electrode mass is usually an advantage because all that electode mass can tend to quench and incipient flame kernel. The ground electrodes are quite "cold" relative to the 4500 degree F temperature of the incipient flame.

The resistor issue was also brought up. Using a resistor plug in place of the OEM non-resistor plugs can alter the voltage wave form and cause idle/emission problems.

Few manufacturers offer non-resistor plugs, so it's best to use the proper Bosch non-resistor plug. Some chains that sell Bosch plugs do not stock the entire line and will try to sell you a different Bosch number. If they don't have the OEM equivalent plug, shop elsewhere. Buy the OEM plug or be sure you have the EXACT equivalent plug from another manufacturer.

The only thing I'm not picky about is the "0" suffix, which indicates a slightly larger electrode. For example the OEM Bosch plugs in my 2.6 are H9DC0, but I currently use the H9DC.

In theory the H9DC0 might have longer electrode life.

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