For a racer that is on a budget running a lower rpm engine here is a great buy on some springs that a well funded team cycles out as part of routine maintenance giving another racer a chance to save some money and get out to the track to play with their hot rod.
Springs are all in the 375 to 400 PSI range at 2.100" installed height. Pac #1360 springs are very common on Fat head Hemis and there is twenty nine springs for this price. Great for two cylinder heads and some spares to keep you going strong out on the track.
PAC 1300 Series Dual Drag Race Valve Springs are designed to have a higher rate than traditional triple springs due to heat treating and alloy advancements for a reduction in physical mass with higher frequencies. These dual drag race valve springs are coiled with a process that enhances durability by engineering the outer spring precision to interface with the inner spring. A smaller, lighter designed retainer and specially formulated spring steel ensures consistency and performance that substantially increases the longevity in extreme conditions, such as professional drag racing. Advantages of 1300 series dual valve springs includes lighter mass, higher frequency, higher rate, extreme engine RPM capability, and increased horsepower.