What spark plugs do I buy?

[mustangfan1990]

I have a AFR 185cc heads right now and I think I have 3924s in there now, but Vortech said I need to go 1-2 heat range colder. The spark plug threads are long so I need the same size plugs but a colder heat range any help here what to get or a part number?

 

[04sleeper]

The plugs you are running are 1 heat range colder than stock. If you would like to go with 2 heat ranges colder than stock the number would be 3923.

Stock plugs are 25's. The "39" is just the number before the heat range number and just means it has a longer set of threads.

Hope this helps.

 

[mustangfan1990]

cool so Ican keep the ones I have now then right ?

 

[04sleeper]

cool so Ican keep the ones I have now then right ?

Yes.

 

[Grn92LX]

3923's.

 

[mustangfan1990]

colder range would help me get farther from det. right?

 

[04sleeper]

colder range would help me get farther from det. right?

True to a point, going too cold could cause driveability problems.

3923's should be fine though.

 

[PUNISHER RACING]

3923's