iridium spark plugs

[valvebounce]

I have a 1999 (December) 25hp Johnson-J25RLEEB.I have put in Iridium equivilent spark plugs (NGK)(champion QL77JC4)
I'm wondering if the iridium plugs are suitable,or if they my damage the power packs.
Anyone got any info,it will be gratefully received.

 

[racerone]

???------Not sure how the material of the tips could somehow damage the powerpack ?-------There must be more to this question or reasoning on your part I think.----

 

[Chris1956]

I think they just damage your wallet.

 

[racerone]

It is a big job to replace the 16 plugs on my 5.7 HEMI.------Glad they work fine for 100,000 miles or more.-----Plugs ( iridium ) are more expensive but save money on labor.----Valvebounce----Do you know what the powerpack does and how it works ?

 

[gm280]

Exotic metals are coming out all over the place. And it is a two fold idea. With new exotic names they make the consumer think they perform way better then any other plug. The fact is those unusual metals help reduce erosion and wear more then anything else. They don't produce a different spark then any other plug. Just "maybe" last a bit longer. But new catch names are selling points... I bet that if you installed a good normal plug with an Iridium electrode plug, you will not notice any different concerning anything. And since marine engines rarely ever see the same usage of vehicle engines, I don't see the point myself. But that is merely my opinion!

 

[valvebounce]

???------Not sure how the material of the tips could somehow damage the powerpack ?-------There must be more to this question or reasoning on your part I think.----

I was reading that resistor plugs can damage your powerpacks,I don't know much about how,but I was wondering if iridium plugs might have the same effect.
i think i will stick to champion QL77JC4's in the furure.

 

[achris]

The power pack produces a very fast voltage spike to the coil. The coil, in turn, steps that voltage up and that's what jumps the gap at the end of the spark plug. The size of the gap and the conditions inside the combustion chamber will determine the voltage at which the spark will jump. Higher pressure and leaner mixtures require a higher voltage. The 'normal' jump voltage of an engine at idle is about 1,000v. Coils can produce UP TO 30,000v, but once the spark jumps, the voltage doesn't rise any higher. The reason for the higher voltage capacity is because as engine speed, load and fuel conditions change, the voltage required to jump also changes, and under very lean, high speed, that voltage can be very high... The down side, a coil that can fire a very lean mixture will also cause detonation, leading to rapid and complete engine 'self-disassembly'...

The type of spark plug will not hurt the power pack.

Chris........

 

[Chris1956]

Some Johnnyrude powerpacks specify a "Q-type" resistor spark plug such as the Champion QL78YC. Your original post said that you had found an equivalent Iridium park plug to the OEM recommendation.

Did it have the correct resistor type for your motor?

 

[racerone]

I like it------" self disassembly "------Sort of like a motor coming to a ---" dynamic halt "

 

[valvebounce]

The power pack produces a very fast voltage spike to the coil. The coil, in turn, steps that voltage up and that's what jumps the gap at the end of the spark plug. The size of the gap and the conditions inside the combustion chamber will determine the voltage at which the spark will jump. Higher pressure and leaner mixtures require a higher voltage. The 'normal' jump voltage of an engine at idle is about 1,000v. Coils can produce UP TO 30,000v, but once the spark jumps, the voltage doesn't rise any higher. The reason for the higher voltage capacity is because as engine speed, load and fuel conditions change, the voltage required to jump also changes, and under very lean, high speed, that voltage can be very high... The down side, a coil that can fire a very lean mixture will also cause detonation, leading to rapid and complete engine 'self-disassembly'...

The type of spark plug will not hurt the power pack.

Chris........

Hi Chris,and thanks.The motor starts first pull and ticks over smoothly,when I increase the revs,it sputters before it picks up,and then cuts out.I can't find the route or names of the coils and stator,I suspect one of the coils under the flywheel may be the cause.Do you have an opinion on the cause?
Could the carb dialling in cause it?

 

[valvebounce]

Some Johnnyrude powerpacks specify a "Q-type" resistor spark plug such as the Champion QL78YC. Your original post said that you had found an equivalent Iridium park plug to the OEM recommendation.

Did it have the correct resistor type for your motor?

To tell you the truth,I don't know.