AC Delco Rapidfire #5 Spark Plugs

[AnytownUSA]

Okay between your picture and Demps saying the small tip was the platinum, I got mixed up. It looked to me that the "red" plug's tip was smaller. Blue is good!

 

[Rob]

Okay between your picture and Demps saying the small tip was the platinum, I got mixed up. It looked to me that the "red" plug's tip was smaller. Blue is good!

It is. Look again at the pics I posted at the beginning of the thread.

 

[Hib Halverson]

The original AC Rapifire #5 was, basically, a high-performance version of the FR2LS, the OE plug for 90-92s.

The AC Rapidfire line was changed early last year from a non-platinum to a single platinum tipped design. Also the center electrode, which on the early RFs was fluted, was changed to a non fluted design. The rest of the RF's hi-po features, including the cut-back, pointed side electrode were retained.

From a performance standpoint the "new" RF5 is the same as the old RF5. The big change somes in spark plug durability, which, in some cases, is extended via the single-platinuim tip.

Of course, with the LT5 and its DIS (which has cylinders firing with both polarities) single platinum plugs only offer the reliability increase in half the cyinders. So, with the new RapidFire design, the benefit to the LT5 user is mainly the slightly better performance gained over the OE plug. It is important to note that with DIS engines, the only way to get the full benefit of platinum tipped plugs is to use double-platinum-tipped units.

Lastly, for LT5s that do not see starts without warm ups and are driven aggressively, the Rapidfire #9 (equiv to the old FR1LS, the original LT5 OE plug) is the best choice.

 

[Rob]

Hib,

Thanks for this information!

 

[lt1george]

ac plugs

The new plugs are probably made in Mexico. What a waste.>George