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.
Comp Cams PN 26915 and PN 26918 beehive springs are direct replacements for the LS1 spring and fit the Vortec head with no machining required. These springs offer more lift capability and more load than the stock springs, and the conical shape results in a lighter retainer that provides increased valve control at high rpm.
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.
The GM Performance Parts Vortec head is an excellent choice for mild small-block Chevy street engines because it offers 400hp potential for a bolt-on price of under $500.
SPRING SPECS
This 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.
The beauty of this beehive spring is that it fits directly over the Vortec's large valveguide without requiring expensive machine work. The only downside is that these new springs are almost twice as expensive.<br><br><br>
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
Component weight in grams
PN 26918 spring: 73
PN 774 retainer: 12
Total: 85
986 dual spring: 115
986 retainer: 28
Total: 143
This is a shot of the stock Vortec valveguide. Note that the large outside diameter of the guide (0.900 inch) is used as a locater for the valvespring. When converting to larger springs, the inside diameter of the spring must be larger than this dimension or you will need to machine the guide, which is an added expense.
PARTS LIST
-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
