Benefits & Pitfalls Of The Vortec Cylinder Heads
Vortec Cylinder Heads
Considered to be the best small block head gm ever made on a production vehicle. For good reason Vortec cylinder heads flow better at low to moderate lifts than any other production head. This allows the flow of air to start sooner and go longer in the intake duration. As the valve lifts the higher flow it makes at low lifts the more air will move across the entire intake event. Once the air flow is started moving the engine will be able to take a bigger gulp of air overall. Along with good flow at max lift these heads can make a large amount of power.
The popular vortec heads 906, 062 and 059
There are two casting numbers used with the Vortec label. Casting number 12558062 and casting number 10239906 Both have good flow. The 906 is considered less exhaust flow at higher lifts. Both of these can make good power with the 062 being the better choice. There is also a 305 version that came on the L30 305 engine and can be a great performance upgrade for many of the weak 305’s blocks on the market for next to nothing. The L30 305 casting number is 12558059.
Both heads also suffer from cracks and Vortec engine use a thin gasket that is prone to leaks as well. With this combination it is often recommended to buy new casting as they are not expensive. Another reason to look at buying new is the Vortec engine itself has some minor issues that may cause failure in its lifetime but for the most part they will reach 200K without much trouble. Once you have 200K miles on an engine the heads have taken a beating and may cost just as much to rebuild at the machine shop as a new set of heads that are bolt on ready.
GM Performance Parts Counter Heads
There are also two performance versions of the Vortec head that can be purchased from gm. A small port that is larger than the stock vortec production head at 185cc intake volume 25534421 and a large port version 25534446 with 225cc intake ports for massive flow in racing engines. Both of these are great heads for racing applications. They can also provide a good improvement over the production castings for street car engines with large cams and increased stroke and bore. The 225cc head are great for drag racing application where high rpm power is the major concern. The smaller 185cc head is a good choice for street strip applications and also works great for road racing and 4×4 competition.
Better Chambers Allow Better Timing
The combustion chambers are also less prone to detonation. Along with a good combustion efficiency they produce more power and less emissions. With more complete fuel burn also comes better MPG and improvement in power production.
The springs are one of the major problems with the vortec heads. Without having a machine shop open up the spring pockets and guides. Without modification these heads will only take .420-.430 inches of lift. Not much for a large cam. When compared to the flow of the heads the lift they can support is very low. Crane cams has a tool machined from 1.25 inches to 1.440 inches spring diameter this allows the use of many after market spring that can support more lift and RPM. Comp also offers a tool to modify the valve guide to smaller sbc valve guide of .530 over the .560 guides that come stock on Vortec heads. Once machined the heads can support .535 and .550 inch lift. Without coil bind of the valve springs. With the 1.440 inch valve springs seat diameter can use dual or single springs.
Once the heads have been machined they can support 400 horsepower without much problem or further modifications. With some head porting a few more ponies can be found.
Vortec Intakes and Headers
These require a different intake and valve covers than standard sbc heads. You will need to find a good intake from the aftermarket for any carburetor install of these engines the factory intake is plastic and used for efi only. These are not suited for performance use and have some issues that lead to replacements being done on a regular bases. The gaskets often leak on these manifolds along with fuel injector issues its best to replace these even if using the head for an efi install. Most of course are for carb install.
Vortec Cylinder Heads Are Well Known
The aftermarket support for these heads has been great. They sell great intakes in many flavors from all the major intake manufactures. The Edelbrock RPM Air Gap Vortec 7516 is a popular intake choice a proven performer. Edelbrock also makes the Performer 7116 intake for lower power builds with a shorter install height. these will fit more cars and trucks with limited clearance.
There are of course many other head choices on the market. The main reason we see so much information on the internet about Vortec head is because of there low cost to hp ratio a good set of stock heads can provide. Vortec cylinder heads are no match for any OEM as cast head. Lots of competition found in aftermarket. Aftermarket also makes a set of heads in aluminum and iron versions. Many have better flow than the OEM heads.