If you're scouring a nearby u-pull-it yard for cheap horsepower, understanding your vortec head casting numbers is basically the top secret handshake of the small-block Chevy world. It's one of all those things where in the event that you know what you're looking regarding, you are able to walk away with a group of mind that'll breathe existence into a tired old engine just for a couple hundred bucks. If a person don't know the numbers, you might turn out lugging thirty lbs of scrap steel back to your truck.
Vortec heads, specifically the particular ones found on the mil novecentos e noventa e seis to 2002 Chevy trucks and Sports utility vehicles, are legendary for a reason. These were the last hurrah for your Gen one small block, plus GM really knocked it out of the park using the port design. But since they produced an incredible number of these things across various platforms—vans, vehicles, and even industrial equipment—there are a few various versions floating close to. Some are great, several are just "okay, " and several are specifically created for heavy-duty work rather than top-end street use.
The Heavy Hitters: 062 and 906
When people talk about the "holy grail" of spending budget factory heads, they're usually talking regarding two specific vortec head casting numbers : 12558062 and 10239906. In the car community, we just call them the particular "062" and the "906. " These were the brain bolted onto the L31 350 (5. 7L) engines within Silverados, Tahoes, plus Suburbans.
The 062 casting is definitely generally considered the particular "purest" version from the head. It includes a three-angle valve chair right from the factory, which helps with airflow. In case you find the set of these types of, you're in great shape. They movement incredibly well intended for a stock iron head—better than some expensive aftermarket stuff from the 1980s.
The 906 casting is just as famous, however it comes with the bit of the caveat. These had been often utilized on heavy duty trucks (like the 2500 and 3500 series). Because all those trucks were designed to haul heavy loads and create a lot associated with heat, GM sometimes gave the 906 heads a solidified exhaust seat. This is great with regard to longevity, but the particular way it was set up can slightly disturb the airflow in the exhaust slot compared to the particular 062. Is it a dealbreaker? Honestly, for a road car, probably not really. But if you're a perfectionist looking with regard to every last horse, the 062 will be usually the one particular people fight over.
Where in order to Find the Numbers on the Head
You'd believe GM would create it simple put the numbers right on the front where you can discover them, but that would be too simple. To get the vortec head casting numbers , you're likely to have to do a little bit of work. These types of numbers are located under the valve cover, cast into the top of the head near the rocker left arm studs.
If you're in a junkyard, this means you'll need to bring a 10mm socket to pop those center-bolt valve covers off. Once you're in there, you'll observe a number of seven or even eight digits. You're looking for those last three digits to confirm what you've got. While you're in there, it's also a great idea to check out the "sawtooth" markings on the ends from the heads. Vortec minds have a really specific three-triangle pattern on the entrance and back from the casting that can make them easy to spot from the range, even before you pull the addresses.
Why the particular 062 and 906 are Different
It's a typical debate on vehicle forums: are the 906 and 062 actually that different? Properly, yes and no. Both heads discuss the same intake slot design, which will be where the magic happens. The consumption port on a Vortec head is definitely designed to make a "tumble" effect because the air-fuel mixture enters the combustion chamber. This leads to a much even more efficient burn, which is why you can often run more timing and make good luck with much less fuel than you could with the old "smog heads" of the 70s.
The difference lies almost entirely in the exhaust side. The particular 906 heads that will came on the heavy duty engines recently had an Inconel exhaust valve seat insert. This put was designed to deal with the extreme warmth of a truck towing a trailer up a mountain grade. To accommodate that insert, the particular bowl area of the exhaust system port was machined differently. In some cases, this leaves a bit of a "step" in the slot that hurts high-rpm flow. If you're building an easy riding bike, you won't see. If you're developing a drag speed, you'll probably would like to spend several time using a pass away grinder to even that out—or simply hold out for that 062s.
The V6 Versions as well as other Castings
Don't let the four. 3L V6 guys feel left out there. The V6 motors from that exact same era also utilized Vortec technology, and their vortec head casting numbers are equally important if you're building a "baby" little block. You'll frequently see numbers like 12556140 or 12557113.
These V6 heads are usually essentially the three hundred and fifty heads with 2 cylinders chopped off. They have the same great port style and the same high-efficiency combustion chambers. If you're working on a S10 or even a Blazer, finding the good set of "true" Vortec heads can take that will V6 from being a sluggish workhorse to some surprisingly peppy very little engine. Just end up being careful not in order to mix them up with the older V6 heads that will didn't have the high-flow ports.
Watch Out for Cracks plus Issues
Just before you get as well excited about obtaining the right vortec head casting numbers , you need to do an actuality check. These heads are made of cast metal, and they were bolted on to trucks that resided hard lives. One of the greatest downsides to the particular Vortec design will be that the castings are somewhat thin to save excess weight. This makes them prone to cracking, especially if the engine ever will be.
The nearly all common place for the to crack is in the combustion holding chamber between the consumption and exhaust valve seats. If you're buying a set through a guy upon Craigslist, bring some brake cleaner plus a rag. Clean the chambers down and look really closely for any kind of hairline fractures. If you see 1, walk away. It's usually more expensive to pin and weld a cast-iron head than it is to simply go find another one.
Another thing to keep in mind is the lift limit. Stock Vortec heads are usually notorious for getting very little measurement between the device spring retainer plus the valve control seal. Usually, something over. 475" associated with valve lift may cause the retainer to smash into the seal. If you're planning on running a big "thumpr" camera, you're want to have the valve guides machined down or even use special beehive springs and retainers to get the clearance you will need.
Making the Change to Vortec
So, you've found your 062s or 906s. You've examined them for cracks. Now what? Nicely, you can't simply bolt them onto your 1980 Chevy 350 and contact it a time without a few other changes.
First off, you need a specific intake manifold. The consumption bolt pattern upon Vortec heads differs from the old-school small block. Instead of twelve bolts that use from an angle, the particular Vortec heads use only eight mounting bolts that go straight down. You'll likewise require self-aligning rocker hands because the mind don't have pushrod guide plates or narrow pushrod slot machine games to maintain things covered up.
It sounds like a lot of hassle, but the particular payoff is worth it. Swapping the set of "good" vortec head casting numbers onto an older engine is definitely one of the particular single best methods to pick up 30 to 50 horsepower without breaking the bank. It's the reason precisely why these heads are still flying away from the shelves at junkyards twenty years once they stopped making them. They simply work.
Whether you're building a budget street machine or just trying to get a little more grunt from your farm truck, maintaining a list associated with these numbers within your pocket is usually the best way to make sure you're obtaining the performance you're paying for. Just keep in mind: check the numbers, check for breaks, create sure you've got the right intake to suit. Right after that, it's all about the smiles for each gallon.