question regarding spark plugs

[soundguy]

While tearing down motor for new HG's, I pulled the plugs to replace them. The ones currently on it are AC R44TS. I've seen some posts with peeps saying they use R42TS. What is the difference? Also been long time since I heard the definition, what is meant by the plug is "colder" ?

 

[soundguy]

let me rephrase it. Would I be better off switching to the 42's over the 44's? wanna know which way to go before I go buy them.

 

[buickpower]

colder or hotter refers to the internal design of the spark plug's center insulator, and how that design affects heat transfer from the insulator to the threads and then to the cylinder head. Basically a colder plug has more area for heat to transfer through at the bottom of the insulator to the threads, so its temp stays lower. The lower the number, the hotter the plug. It is always said to run as cold of a plug as you can (to stave off detonation) with out fouling it. If the tip of the insulator is too hot, you will get detonation. So your heat range will vary depending on what you are doing, i.e. racing vs. street driving. Probably wouldn't hurt to run a 42 or 43 as a starting point.

 

[soundguy]

so running 44's would be better as long as the plug shows fine. The ones I removed show no bad signs other than typical wear on electrode.

 

[buickpower]

whoops i edited my post after you posted again. I'd try a 42 or 43 for the street.

 

[kh440]

I would have to agree. the 43 seems to be a better plug for udgraded fuel systems.

 

[buickpower]

whoops I forgot AC plugs are colder the lower the number. still try the 43's

 

[GNVYUS 1]

43's would be great for a street car not running alky or high octane at high boost all the time.

42's are generally used with alky or frequent high boosted runs.

I would not run the 44's unless the cars totally stock with around 14psi of boost on the stock turbo.

 

[BEATAV8]

Just as important is the gap. Set it at .028"-.030"

If the gap is wider you may have misfire problems under boost.

 

[soundguy]

Well I do plan on getting the progressinve alky kit in near future. The turbo was also upgraded by a previous owner, but have yet to find any number on it to identify for certain what model it is. I'm thinking its a ta-49 since that is one of the few I've been able to find that uses the Garrett A/R .60 housing.