The hottest cylinder head on the small-block Chevy hit parade right now is the Vortec iron head. It's extremely affordable and flows a bunch of air for a stock production iron head with a 170cc port volume, making it the ideal cornerstone for a budget 400hp street small-block. If the Vortec head has an Achilles heel, it would be the valvesprings. The stock Vortec springs are designed to control a very mild stock cam. The biggest hurdle is accommodating valve lifts above 0.450 inch.
Since even mild performance cams stretch the valve-lift envelope into the 0.500-inch range, the Vortec heads require modifications to the valveguide to allow more lift and new springs. This machining operation can be easily accomplished by any automotive machine shop, but it adds to the cost of the heads. As an alternative, Scoggin-Dickey Parts Center and other GM Performance Parts dealers offer Vortec heads that have already been modified, but as you might expect, this also drives up the price.
Recently we ran across another solution. Comp Cams' new "beehive" or conical valvesprings are similar to those used on GM's Gen II production LS1 and LS6 engines. These springs are wound with an ovate, or oval, wire that creates more room for valve lift before the spring reaches coil-bind. In addition, the smaller beehive design reduces the retainer diameter and weight, which helps the spring do a better job of controlling the valve at high rpm. But perhaps the best news of all is that these springs will bolt right onto a stock Vortec head with no machining required. These springs also increase the amount of available valve lift from 0.450 to 0.550 inch. (The spring can accommodate as much as 0.665-inch lift, but when installed at 1.800-inch height, the retainer-to-seal clearance limits lift to slightly more than 0.550 inch.)
These springs are more expensive than standard valvesprings, but the cost is commensurate with their performance capabilities. When you consider these simple springs do an equal job to a dual spring and are lighter to boot, there just might be something to this conical thing.
Spring SpecsThis chart compares the two Comp Cams conical springs to an older dual spring. The second portion of this chart shows the difference in weight between the conical and dual spring. The dual-spring combination is 40 percent heavier than the conical-spring combination. Given that both springs offer basically the same seat and open loads, the conical spring would offer more valve control due to its reduced mass.
Valvespring PN 26915 PN 26918 PN 986 Outside/inside Dia. 1.290/0.885 1.290/0.885 1.430/0.697 Seat load 105 @ 1.800 130 @ 1.800 132 @ 1.750 Open load 293 @ 1.{{{200}}} 318 @ 1.200 310 @ 1.200 Coil bind 1.085 1.085 1.150 Spring rate 313 313 296 Weight Component (grams) PN 26918 spring 73 PN 774 retainer 12 Total 85 986 dual spring 115 986 retainer 28 Total 143
Parts List
Component Manufacturer PN Price Valvespring, beehive Comp Cams 26915 $186 Valvespring, beehive Comp Cams 26918 186 Retainer, steel Comp Cams 774 59 Keepers, 7-degree Comp Cams 648-16 28 Dual spring kit Comp Cams 986-16 85 Retainers for 986 spring Comp Cams 740-16 60 Keepers, 10-degree Comp Cams 611-16 26 Vortec cylinder head GMPP 12558060 489/pair* Vortec head, modified Scoggin-Dickey SD8060A 639/pair* * Scoggin-Dickey price
