308 spark plugs

Do not waste your time with platinum plugs. Those who had tried ngk iridium plugs have had success with them although I cannot justify the expense and I doubt there is any performance gain. The iridium plugs may last a little longer, but I prefer replacing the plugs often so I can see what is going on inside the engine on a regular basis. Better to know if something is going awry before it does. Use NGK BP6ES and replace them every couple months or so depending on how much you drive the car and you will be pleased.

 

+1 on NGK BP6ES. Unless you are running really, really rich, or you are racing your car, there is no need to change plugs every few months. Once every year or two is more than often enough for ordinary street use, or even "spirited" driving. It doesn't hurt to check a plug on each bank now and then to be sure they are not getting too dirty. But if the car is running well, chances are the plugs are fine and don't need to be changed very often.

 

IMHO, there will not be a noticeable difference in engine power between the regular plugs and the Iridium plugs. If there is any difference, it will be so small as not to be felt seat of the pants. I have never seen anything that proves there is a significant power difference. It is my understanding that the main difference is serviceable life. The iridium plugs are used in the newer cars to extend the service intervals and to handle the computerized ignition systems and direct discharge coils. In an older car, changing to iridium buys you nothing except more expensive plugs.

 

While there may be be no "noticeable difference in power", the performance of the Iridium plugs remains consistent over it's longer life span...hence, more consistent hp output over the life of the spark plug.

All cars, regarless of age or ignition type rely on the spark plugs. The plugs doesn't know the diffference between fuel injection and Weber carbs. Longer plug life benefits all engine types.

Really? The fine wire electrodes used in the Iridium plug resists fouling due to it's higher tip temperature and is truly self-cleaning. How do you explain that the Iridium plugs in my 365bb have been in for 5 years and yet, I was lucky to get one season out of the comparable BP7ES, with no other changes...Note that the BB has no choke or cold starting circuit, so it's "pump and pray" on a cold start. This certainly is a good test for any spark plug "foul resisting" capabilities.

Most folks, with "older cars" who have switched to the Iridum plugs experiece better running cold and a smoother idle.

Of course, your mileage may vary...

Regards,
David

 

Your mechanic is talking about the dynamics of the flame kernel and flame quenching of the spark which a particular electrode generates. I have personally not had great luck with exotic spark plugs on old Ferrari's, which is not to say others have not had good luck with them. I agree with the above poster in that there will not be any difference in power, and if there is, it will not be anything you will be able to notice by the seat of your pants. If they make another 2bhp I would be surprised really. Do not give trivial things such as spark plugs too much thought, and go with what you want while knowing what the concensus is here We are not reinventing the wheel here.

 

David,

I thought I'd made it clear that longer life, as you've experienced, is a benefit of the iridium plugs. I'm glad you have experienced better performance. I'm not surprised that you have found the iridiums better than the BP7ES plugs. In my experience with these cars, the BP7 is too cold a plug. I've found the BP6s seem to burn better and give more consistent running, and hold up well over time.

But as you said, YMMV.

Steve

 

I am using BP8ES they are a lot better in the range between 6000-8000 RPM.
If you are running the engine on low rpm then BP6 or BP7 are better but on high rpm it is better to use colder ones.

Reuven

 

How does the Iridiums perform on a QV? I plan to get a set.

 

Actually Steve, with the JE 12:1 compression pistons I'm running, the "7" heat range really works out quite well. For a more normal Ferrari engine, I agree with you that the BP6ES is a much better choice.

Regards,
David

 

On 12:1 I would use BP9 or B9.
High comp engine works the best on high rpm and needs colder plugs.
Reuven

 

It can vary depending on the version of 308 we are talking about. Definitely the carb 308's prefer the NGK 6, but the FI 308's can often run fine on a NGK 6 or colder 7.