How to Choose the Right Spark Plug???

[Chalky]

Ok, so we all know that the factory spec replacement for the SVO is the Motorcraft AWSF32-C, but if you want to go with something else, apart from looking at the parts store webpages for a recommendation, how do you decide the correct plug for your engine?? How do you determine the correct heat range etc?? Experts, please chime in!!!!

[Meotchh]

Stock? Modified?

[Chalky]

Exactly!!! an answer on both senarios would be helpful

[Bob Holmes]

At one point I used to recommend the NGK TR5, however, after several broken porcelain incidents I believe that plug is too hot and now use the TR6.

[Chalky]

I've been using the NGK TR5 IX for years with no problems but someone recently said it was too cold a plug. I was wondering how to determine that??

[MikeFleming]

If you start having cold-start and idling issues where the plugs are fouling, then it's too cold. Otherwise, you're good to go.

Someday I'll post a pic of how/where to read the actual temp of the electrodes. But it's tired and I'm late now.

[Bob Holmes]

Chalky, it most definitely is not too cold. NGKs numbering of plugs for heat range is backwards from everone else's, so that may have been why you recieved that advise. I broken porcelains with the TR5s on a consistent basis, which is an indication of too high a heat range. Changed to TR6s and it eliminated the problem. This was on the racecar.

[MikeFleming]

I broken porcelains with the TR5s on a consistent basis, which is an indication of too high a heat range. That's also a sign of rampant detonation.

[Meotchh]

That's also a sign of rampant detonation.

It's also a sign that Bob has worked on your car!

[MustangRacer18]

You want the hottest plug you can handle without detonation/melt piston. The hotter the plug the easier it is for the flame to get started and the quicker the burn time which is good for thermal efficiency. The spark plug is the hottest thing in the cylinder (hence you burn holes in pistons directly under the plug). It's very very rare to auto-ign before spark (see my other explanation in CR thread) so it can come down to what your pistons can take heat wise but it is possible to ignite before spark. You also want to run the biggest gap your ignition system can handle....again aids in flame generation and start time. Also plug with multiple straps are JUNK! Its a marketing scheme....the spark will always travel the path of least resistance. You'll never have a dual spark. Also the multiple strap plug shied the spark from turbulence which is bad and they extract more heat from the early flame generation making it even more hard for it to get going...this delays flame propagation and hurts thermal efficiency.

[beeker]

I Engresh please LOL

[oneowner88lx]

If you are running a stock or close to stock you can always cross the motorcraft number over to lets say an NGK number. A lot of manufacturers have conversion charts on line.

[Patrick]

954

Eenie Meenie Miney Moe ...

[Eyelawdoc]

954

Eenie Meenie Miney Moe ...

I see Pat has started posting his baby pictures! Next he'll be posting one of himself with his bottle.... probably Dewars if I know Pat!