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Old 05-21-2010, 07:42 AM   #1
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Possible Vortec L31 sticky....

I've been hanging out on this section of the forum for that past year or so. And I've seen lots of threads aimed at the Vortec 5.7 swap. With most threads asking the same questions over-and-over about wiring, performance, interchangeability, and general swap specifics. So I figured I would write up this thread to consolidate information.

A bit about the engine:
The Vortec L31 engine is a "traditional" 5.7 and can be found in almost every fullsize truck from '96 to 2000 and the big Express vans from '96 to '03. This engine was replaced in favour of the more powerful and efficient LS-series of engines.

Specs:
Sporting a modest compression of 9.1:1 and very street friendly. Power numbers jumped around from GM's claim of 220HP / 330lb-tq. GMPP did extensive testing on this engine as it's the foundation of their popular Ram Jet engines. They showed numbers 15~20 higher than GM's. The famous Vortec heads are also found on this series of engine. Stock cam specs were .414/428 lift and .191/.196 duration.

Heads:
The ever-popular Vortec heads are based off the second-GEN LT-series of engines. With similar runner and combustion chambers, but that is where the similarities stop. Featuring 1.94/.150 valves typical of GM, and a smaller combustion chamber of 64cc. These heads can support over 400HP out of the box and can pull up to 6000RPM.

While being arguably the best heads to ever come out of GM, they do have their drawbacks. First thing people will notice is they are cast iron, while being heavy; they are also very stout and durable. By far the biggest drawback is the limited lift capabilities. The Vortec heads can safely handle .450 lift. Some people can get away with ~.470 due to varying casting and assembly techniques. It's still a safe bet to check for coil bind on anything higher than .450 lift. Personal opinion; I feel the centerbolt-style valve covers are a drawback. While they do seal better than perimeter-style covers, they do limit the rocker options. Self-aligning "narrow" rockers are required to clear the internal bracing and through bolts of the covers. And 90% of the time full-rollers wont fit under stock covers. Requiring the use of tall style covers, which often times wont fit under the stock sepentine-belt brackets.

Vortec heads can be found in two castings; the -063 and -906. The -906 castings were used on the heavy-duty trucks and had a hardened exhaust seat. It was believed that these beefier seats inhibited flow and altered the compression chamber shape limiting the effectiveness. Recently this has proven to be false. There is no difference in flow between the two.

Block:
Vortecs used GM's -880 castings, it's basically a "traditional" cast iron SBC block with provisions for a roller cam and a one-piece rear main seal. Being "traditonal" means that almost any GM SBC part will bolt to it. One thing to watch for though, the timing covers. The Vortec uses a plastic timing cover that uses uses 8 bolts. Regular timing covers use 10 bolts. Some blocks had all 10 holes drilled and tapped, while others only had 8. The timing covers will still interchange, and somewhat seal decently.

With that being said, I would just like to restate that ANY small-block cam will fit. Whether it be the older flat tappet cams, the LT-series cams, or roller cams. Any rotating assembly provided it is a one-piece rear main. Any SBC water pump, flex plate, heads, distributor, etc...

Induction:
The Vortecs main drawback is without a doubt the induction. While being multi-point injection, it doesn't use traditional injectors. Instead it used this new design they call "poppets." They are essentially an extension of the fuel lines with a check ball in the end. When pressure exceeds the limit the check ball opens and sprays fuel. These poppets are fed from a central fuel block at the top center of the intake. They are a fixed 19lb injector and operate on 55~60PSI. These entire injection assembly is under the intake plenum. This entire assembly, the fuel block, lines, and injectors are often referred to as a "spider."

Here is the problem; the stock poppet injectors are prone to fuel deposits and clogging. One company sells a replacement "spider" assembly that uses a mini-traditional style injector in place of the poppets. It does what it's supposed to in increasing reliability and eliminating clogging. But they don't do anything for performance as they are still rated at 19lbs. That in it's self is still the problem of the L31 injection...nobody makes a larger injector for the system. There is one company that claims they did, but it was later discovered that they increase the dwell time on the injectors and fuel pressure, essentially holding them open longer. They are still rated at 19lbs though.

The stock injection system, when in good working order, works well for it's intended purpose. And has been proven to reliably feed 375~400 crank horsepower. But when the system is in question it isn't capable of reliably feeding a worn-out stock engine. Like the old cliche goes "When it works it works, when it doesn't....it doesn't."

That's it for now, I'll talk more on performance, fixes, and upgrades tomorrow. And dive into swap specifics.
Old 05-21-2010, 07:50 AM   #2
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Thumbs up Re: Possible Vortec L31 sticky....

Sticky........Sticky.......Sticky!!!
Old 05-21-2010, 11:44 AM   #3
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Re: Possible Vortec L31 sticky....

Good info but I see 2 things that are incorrect.

1.) the compression ratio. Stock compression ratio is about 9.4:1 (at least that what my service manual says for my 97 full size).

2.) the second casting number for the vortec head is not 063 but 062. The 062 is identified by the 3 'saw tooth' marks on the casting itself. You can goto GMPP can get vortec heads. They will have a 060 casting number typically.
Old 05-21-2010, 12:59 PM   #4
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Re: Possible Vortec L31 sticky....

Quote: Originally Posted by zap-mann
casting number for the vortec head is not 063 but 062.
Yeah, you're right. I knew that too, just a typo...keys are too damn close together. And it wont let me go back and edit my post for some reason...

And about the compression, I've read it's anywhere from 9.1 to 9.5:1. I've just seen it mentioned in more than one place as being 9.1 so that is the number I went with.
Old 05-21-2010, 01:41 PM   #5
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Re: Possible Vortec L31 sticky....

Here is a link to the best vortec discussion that I have ever read.

http://www.nastyz28.com/forum/showthread.php?t=56505
Old 05-21-2010, 04:27 PM   #6
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Re: Possible Vortec L31 sticky....

All right, part two. Here we go...

Internal engine:

I'm going to skip cam selection, since there are thousands of designs out there and every application is different. Same with rotating assemblies, just stay away from those cheap stroker "kits" with the Japanese cast steel cranks. If you're not spending more than $1500 on a rotating assembly, before balancing. It's not worth having. One thing that needs improvement is the timing chain. The stock "link" style chains are prone to stretching, they are purposely built as the weak link in the system to aid in absorbing harmonics. In stock configuration, the Vortec has a reluctor ring between the timing cover and crank gear for the crank position sensor. This takes up room under the timing cover and wont allow the use of a double-roller chain. A gear drive will physically fit. But the design relies on the idler gears thrusting against the timing cover to keep them in place, the plastic timing cover simply wont last and the gears will wear right through it. Besides; a gear drive is a no-no when used on anything with a knock sensor anyway. As of this writing, there is only one upgrade to the timing chain. GMPP's heavy-duty single roller used in their ZZ series of engines. It's stronger than a factory "link" style chain and stronger than most double rollers. It has more links on the chain too which allows it to run "quieter" to keep knock sensors happy.

Most L31s came with a dinky windage tray, the purpose of a windage tray is to keep oil in the pan. The up-and-down motion of the pistons causes oil to go crazy. The downward motion of the piston forces air into the the oil in the pan and splashes oil up. This oil splashing onto the crank can slow it down by adding weight and resistance. The upward motion of the piston creates a vacuum and pulls the oil up with similar effects. Windage trays act as a barrier between the piston's force and the oil, keeping oil in the pan where it belongs. The factory windage tray just covers the sump of the pan, keeping oil in the sump unaffected and down where the pickup is. Any engine will benefit from a full length windage tray by keeping oil where it needs to be. Even a cheap "baffled" tray is better than nothing at all. Higher-quality oil pans will incorporate a built in windage tray and a crank scraper. A crank scraper is just as the name implies, it places "blades" near the crank and is designed to scrape oil of the crank's counter weights as it rotates. Personal opinion: I prefer the bolt-on design that requires longer main bolts. This allows me to tweak the windage tray as I see fit. I ran into a problem with a Canton pan with a built-in windage tray and it not letting my dipstick see fully.
Heads:
The consensus is to not touch the intake side of the head or the combustion chambers in regards to porting. All though "clean up" to remove flashing or casting marks is okay, most people don't even bother to clean it up. The exhaust side will benefit from typical porting and polishing work.

Like I mentioned above, the valve springs are really the only drawback to the Vortec heads. This can be overcome by a competent machine shoppe working their magic on the seats and guides to install larger springs. But this can easily double or triple the cost of the heads. Aftermarket companies have found ways around this, the simple "bolt on" upgrade will use newer LS-engine "beehive" springs. They are wound with an oval wire as opposed to typical round wire. This allows them to compress further and reduces overall weight of the springs. The problem with this is the LS-engines have a different valve stem diameter than a "traditional" SBC. So you can't use the LS-engine's retainers or keepers with the springs. And the traditional retainers and keeps are too large to work with them. But alas, Comp Cams makes special keepers and retainers for use with these springs. Using the LS springs with Comp's hardware makes this an moderately priced "drop-in" upgrade that will allow Vortec heads to safely run ~.550 lift. At the time of writing this, new springs and hardware was right around $450 shipped. There is yet another alternative for mild engines where increase lift is needed. Remember, the Vortec head is still a "traditional" SBC head, which means it's interchangeable with other SBC parts. One of which being the famous Z28 springs. Z28 springs are a true "drop-in" reusing the Vortec's keepers and retainers and will safely allow for ~.525 lift. These springs were less than $30 shipped from Scoggin Dicky. Scoggin Dicky also offers a "kit" for SBC heads that was right around $100. The kit uses their house brand heavy duty springs, retainers, keepers, and shims. They say this kit will allow for ~.600 lift. And yes, they are a 1.25 spring...which means they will fit Vortec heads. Personal opinion: another technique floating around the internet is what they call the "ghetto grind." Which is basically grinding the lower portion of the retainer off to increase the distance between the retainer and seal. When properly done it will allow for an extra .010~.015 lift. But improperly ground retainers will drastically weaken them, and heavy grinding will scorch the metal further weakening them. I don't recommend this route, especially when quality "low profile" retainers can be had for less than $20 a set.

Rocker arms are without a doubt the quickest, cheapest, and most affective "bolt-on"upgrade one can do to an engine. They can be had in many flavours, stamped steel which is what you will find stock. Stamped rockers with a roller tip, full roller rockers, and shaft-mount rockers. Shaft-mount rockers wont work with centerbolt heads so don't even bother with them. Roller-tip rockers really only decrease valve stem wear, and don't do much for performance. These should be over looked in favour of full rollers if any upgrade is going to be made. Vortecs have limited options when it comes to roller rockers. Mainly due to the center bolt design and the lack of room under the valve cover. Aluminum rockers are too bulky to clear the internal bracing of the valve cover, even if one cuts or trims the bracing. The valve covers are still too low to clear aluminum rockers most of the time. "Narrow bodies" rockers like Comp's Pro Magnum, Crower, and other stainless rockers will usually clear internal bracing and baffles with very little, if any trimming.

Understanding rocker ratios; The stock rocker arm ratio is 1.5:1, meaning they will increase the cam's lobe lift by 1.5-times. Most companies lift numbers are the total gross lift using 1.5 rockers. A popular upgrade is the step up to 1.6 rockers, increasing lift by 1.6-times. While this doesn't seem like a lot at first, but they generally increase lift by .025~.035 which will put you over the limits of your valve springs if you're not paying attention. A simple math for this is take the lift of the LT4 "Hot cam" for example. Take the .525 gross lift, divide that by the stock rocker ratio, in this case it's 1.5. This will get show that the lobe lift of the cam is .350, then multiply that by the upgraded rocker's lift of 1.6 for a grand total of .560 lift. Adding 1.6 rockers to the "Hot Cam" just put you over the limits of most valve springs. The formula is...

(Gross lift / stock rocker ratio) = (cam lobe lift x new rocker ratio) = gross lift

A note on 1.6 rockers. These rockers achieve a higher lift ratio by moving the pushrod closer to the fulcrum. The Vortec heads use a self-aligning rocker arm, so the need for guide plates aren't required. This means the pushrod holes in the head are usually smaller and tighter than that of heads that use guide plates. Since the 1.6 rockers physically move the pushrod's location, it's possible the pushrod could come into contact with the guide holes. It's an easy fix with a drill or a file, but it does produce shavings and dust if it's done on the engine. The physics of increasing the lift by pulling the pushrod in also creates more stress at the pivot point. 1.6 rockers will usually have larger, beefier fulcrums for this reason. While more bearing contact area and durability is never a bad thing, the larger fulcrums can sometimes interfere with the bolt shafts of the centerbolt heads.
Old 05-21-2010, 06:28 PM   #7
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Re: Possible Vortec L31 sticky....

Second part of part two:

When upgrading valve springs with higher spring rates and seat pressures. It's necessary to upgrade the rocker studs to the screw-in type. With stock springs the rocker arm acts at a pivot point, with the pushrod acting as a lever exerting force and opening the spring. With stiffer springs, the spring is acting as the pivot point and the rocker acting as a lever. This will result in the rocker studs pulling out. The first option here is to take the heads off and send them back to the machine shoppe, they will mill down the stud bosses, tap the holes and install bigger, longer studs in place of the pressed-in factory studs. The second option is to replace them with replacement screw-in studs. This is not typically done as a performance upgrade, but as a means of a fix to pressed-in studs that have worn out the stud bosses and pull out. These replacement studs are the same dimensions of the stock studs, just threaded on both ends. After pulling the factory studs, tap the hole in the stud boss and screw in the new stud. This requires removing the head as well due to the metal shavings, and a special alignment tool, and two or three quality taps. The alignment tool slips over the neighbouring stud tightly, and keeps the tap perfectly straight as you thread the hole. When done properly it's just as affective as the machine shoppe method, just cheaper and still appears to be stock. The final method is the pinning method, which is just as the name implies. Drilling one hole through the stud boss, into and through the pressed-in stud, straight on through to the other half of the boss. Then shoving a roll pin in to "pin" the stud in place. If this method is to be done, radius the edges of the new hole to round them off. This will increase strength and prevent sharp edges from cracking under stress. Then slather the roll pin in a good thread locker and drive them in place. This can be done on the vehicle if you can be clean and carefully keep the shavings from getting down in the engine where a shop-vac can't get to.

Induction:
Like the heads, the intake will see very little if any benefit from port work. Just typical "clean up" work on any flashing or casting marks. Just as the "spider" is the downside to the fuel system, it's also putting a hurt on the air induction system. The "spider" being under the plenum physically blocks the incoming air. While it still flows enough to reliably feed stock to mild engines. It does become and issue on wild, high-RPM, or forced induction builds. The only option is to remove the "spider" assembly all together, enter the infamous marine intake. The marine intake are factory pull-offs from(you guessed it) marine applications. This heavy, cast iron unit does away with the poppet design and uses real injectors placed outside of the plenum in the runners where they should be. Although this is a Vortec intake matched to Vortec heads, and uses the same sensors and injector pod plug the L31 does. It's not a direct bolt on and requires extensive modifications to work. These items are scarce, so expect to pay upwards of a grand for the unit....if you can find one. But the ability to run upgraded injectors, better airflow, and larger plenum volume make this the ultimate performance upgrade and worth every penny.

There are a few mods that can be done to the throttle body, they are free too! The first thing one should do to a throttle body is remove the diffuser blade. This is the "half-umbrella" shaped piece on the bottom of the throttle blade. The diffuser is riveted to the throttle blade, you can either cut the "umbrella" section off or you can drill the rivets and remove the entire diffuser. The latter of which will net a few more CFM than cutting it. While you have the blade off, you can put a slight chamfer along the upper edge of the blade to "cut" and smooth the incoming air, essentially creating an airfoil. Slightly polishing the bore of the throttle body and blade can also be done. Remember, like the heads and intake you don't want the bore to be perfectly smooth. You need the roughness for the air to "tumble" across and increase air velocity. Personal opinion: porting a throttle body is a waste of time. Looking at some companies online that offer porting, I noticed they not only remove the very little ridge the throttle body rests against when closed(acting as a seal to keep idle steady) but they also smooth the bottom of the bore, eliminating the narrow part canceling the ventruri effect which also increases air velocity.

Removing the center bars and screen from the Mass Air-Flow(MAF) sensor doesn't do anything for power. If anything it hurts power and can damage the MAF. Also along the lines of worthless mods, throttle body spacers and cold air intakes are on the list. Spacers were designed for low profile carbed intakes to allow the air and fuel more room to atomize while entering the intake. That being said, they don't do anything for hi-rise intakes, or dry throttle bodies moving just air. Cold air intakes are another waste of money, the stock intake ducting and airbox are more than capable of feeding a modified engine. Just make a habit of blowing out the paper filter whenever you change your oil. And replace it if you live on dirt roads.

Headers are specific to swaps and mount options. Full length headers offer the best gain. Shorty headers with short primaries and small collectors offer little in the means of power over modern exhaust manifolds. If you must run headers, spend the money on a quality header that is coated inside and out, and a beefy flange. And avoid wraps at all cost, they trap moisture and rust out headers in a matter of months. Use quality bolts too, avoid the $7 bolts on the shelves at parts stores. They are soft and made of low-quality metal. They wont expand with heat as your heads to, and that is why header bolts work loose and leak.

I'll hit more on some performance and general dos-and-don'ts for the L31 tomorrow, as well as dive into swap specifics.
Old 05-23-2010, 08:47 PM   #8
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Re: Possible Vortec L31 sticky....

Dos and don'ts:
First thing one should look at, whether swapping in a complete salvage motor or building from the ground up. Upgrade the intake gaskets! GM used a plastic gasket base with O-rings embossed around the cooling and intake ports. The problem with plastic is it's weak, and after the constant heating and cooling down it goes through with the engines. It becomes brittle and breaks down. Another problem is the plastic tends to "squish" and break if one isn't careful when torquing the intake down. Fel-Pro has a fix to this with their Perma-torque gaskets. They use a metal base instead of plastic with the same O-rings embossed at the ports. They are more tolerant to over torquing, heating and cooling, and they last forever. The intake should be tightened to a final torque of 11ft-lbs. The bolts, threads, and holes should be perfectly clean to get a good, tight seal.

General swap:
Like the headers, there is no "better" swap method and depends on the owners preference. Refer to the swap sticky for the general needs and build your swap from there.

The '96 and newer 4.3 SEFI (VIN W) engines can reuse the factory harness and ECM with very little modification. No more than adding a few wires and repinning the harness. The ECM must be reflashed a V8 to fire the two extra injectors. The 2.8 engines, and older trucks must use the ECM and harness from the L31's donor truck. The L31 and newer 4.3 use the "black" ECM, it's very capable of running the L31 almost any tranny GM offers, the only drawback is it's only capable of controlling a single electric fan. The newer -0411 or "silver" ECM is a popular upgrade and is a faster and "smarter" ECM, able to control any powertrain combination and dual electric fans. It's just a matter of repinning the L31 harness, but otherwise uses the same connectors.

Another question I see asked a lot is "Will transmission "X" bolt onto the L31 and can the ECM run it." The simple answer is yes. Being a "traditional" small block. Any GM tranny with a 90* bellhousing will bolt to it, and the ECM will control it with the proper tune. From there it's just a matter of having the proper torque converter and mount configuration. Again, the converter and mount options are dependent on the owner's preferences.

Cooling and front accessories:

By now you should be familiar with the L31 being a "traditional" small block and just how tolerant it is with interchangeability. The 4.3 waterpump, accessory brackets, starter, flywheel/flexplate, almost every external part will transfer over from the 4.3 and bolt right onto the L31. With the exception of the oil filter relocator/cooler.

The 4.3 radiator, when in good shape, is capable of cooling a stock/mild engine. And will allow you to reuse the 4.3 cooling components like the hoses and thermostat housing. Another popular option is the Corvette radiator. It's smaller than the 4.3 unit, but has more fins per-square-inch so it's more efficient, but clogs more easily. Being smaller it requires custom mounts and hose connections as the outlets are also smaller. It also doesn't offer engine-oil cooler hook ups if you plan to reuse the stock system or adapt the L31's oiling system. Personal opinion: I don't recommend an engine oil cooler, unless one wants to spend money on quality parts. The "spin-on" adaptors are usually cheap pop metal and warp causing leaks, and require an O-ring change anytime the oil is changed. The oil-lines are notorious for leaking, and don't do much for heat dissipation as they are routed close to a hot engine and exhaust. Quality(money) parts are reliable and can be used effectively. These are usually machined billet adapters that bolt on in place of the the factory spin-in filter location and use braided hose with quality fittings. I'd recommend substituting synthetic oil in place of an oil cooler.

Another possible option is to mount the radiator in the "forward" location. This involves relocating the AC condenser(if you want to keep your AC) and mounting the radiator inside the the core support. This usually involves a bit of cutting and fabrication to open up the hole for the radiator to sit in. And fabbing up a way to mount the radiator and condenser. That, when combined with electric fans, will free up an extra four~five inches of engine room.

The 2WD trucks can reuse the L31 oil pan with no problems, there is plenty of room for it. The 4WD trucks however aren't' as lucky. While the pan will fit with if one is handy with a hammer. A dent must be beat into the driver's side of the pan at the sump for front diff. clearance. The amount beat in will depend on the mounts used and engine location. The oil drain plug is also very close to the diff. and will soak the front end anytime the oil is changed. Requiring dropping the skid plate on ZR2 models. Personal opinion: The oil pans designed specifically for the 4x4 swap offer benefits that highly outweigh the cost of the pan. The pan's convenience and assured clearance are well worth the money for the 4x4. Not only do most of them offer a higher oil capacity, but also put the drain plug at the rear of the sump in the factory location, making oil changes clean and easy.

I'll talk more on swap specifics and how to modify the 4.3 harness to work with the L31 harness in my next post.
Old 05-27-2010, 05:04 PM   #9
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Re: Possible Vortec L31 sticky....

i just have one thing to add about the iunduction on the 5.7....they have a marine intake that mercruiser engines used, they are on 5.7 and 4.3 and are MPFI with change able and upgradable injectors. A large portion of the guiys running bosst run those intakes.
Old 05-28-2010, 10:00 PM   #10
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Re: Possible Vortec L31 sticky....

this has been a great write up...this is the swap i want to do....i can do it but the wiring part is not my thing ....can't wait to read your next post on how to mod the 4.3 wiring.
Old 06-15-2010, 08:30 AM   #11
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Re: Possible Vortec L31 sticky....

All righty, I'm back. Had to take a bit of time off to move and spent some time working on my truck. One of my salvage-yard Vortec heads were cracked.

Wiring:
The wiring is easy, even if you are one of those people that open the hood of a vehicle and throw your hands up in the air. You can do these very simple wiring modifications.

First and foremost, one must acquire a V8 pod plug. These are still available from dealers, some aftermarket harness suppliers, and salvage yards. If you get it from a dealer, save yourself some time(and them) by taking them the part number. 12167618.


If you get the pod plug from the dealer, it will come bare. But will include all the necessary terminals, grommets, and gaskets. Basically everything but the wiring and tools.

With the V6 harness in hand, look at the bottom of the V6's pod plug. Looking at the bottom(engine side) you will notice the plug has little notches(red arrows) at every terminal. These notches act as locators to keep the terminals straight inside the plug. These notches also allow access to the locking tabs that keep the terminals in place. Insert your tool into the notches, while gently puling on the wire from the other side, wiggle the tool a bit and it will eventually depress the locking tab and allow you to pull the wire and terminal out. Personal opinion: I do a lot of wiring, I make and modify my own harnesses. This had led me to invest in a terminal tool. It's basically nothing but a long, thin needle that fits perfectly inside most of GM's weatherpack-type terminals. You can however use anything that will fit inside the notch and wont bend easily. I used a thin paper clip before I bought my tool.


This picture shows the locking tab on the terminals. The bottom is the new terminal that came with the pod plug, the arrow points to where the tool needs to push the tab down to unlock it from the terminal. The top shows a tab that has been abused and lies flats, it doesn't lock anymore. But it's a good example of how far the tab needs to be pressed down to unlock. It also shows the proper crimps in the terminal.


After you pull the terminals out of the V6 plug, transfer them to the new V8 pod plug. Looking at the top(hood side) of the V8 plug, you will see that is each terminal hole has a letter by it. You are now going to transfer your existing V6 wires into the new V8 plug. Put a light coat of die-electric grease on the rubber grommets to help them slide in easier. And slowly, but firmly press the terminals into the corresponding holes until you hear a little click. Then gently pull on the wire to make sure it's locked into place. This is where each wire plugs into the pod plug at.

Injector one (black) into pin A

Injector two (green/black) into pin H

Injector three (pink/black) into pin D

Injector four (blue/black) into pin E

Injector five (black/white) into pin N

Injector six (yellow/black) into pin M

Now, you will have to add four more wires at this point for injectors 7 and 8. Refer to the picture above to see how to crimp the terminals onto the wires, it's easy to do. The thing to pay attention to is making sure the grommet crimp stays round so it fits into the pod plug correctly. The factory wires are 18guage.

Injector seven (red/black) into pin S

Injector eight (blue/white) into pin J

The pink wires are the power wires, all they do is supply 12v to the injectors. It doesn't matter which wire goes into which pin since they all come from the same source. Just install the pink wires into the empty pins on the pod plug. If you did things correctly, the empty pins should be K, L, F, G, R, P, C, and B.

You can get the power for injectors 7 and 8 from any key-on 12v source of your choosing. I spliced into the control(pink) wires for injectors 5 and 3 to control the two extra injectors on my swap.

This picture shows how the wires should look after being installed
Old 06-15-2010, 09:21 AM   #12
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Re: Possible Vortec L31 sticky....

Route the two ground wires (red/black) and (blue/white) for injectors 7 and 8 back to the PCM how ever you choose. I pulled the wire loom off the factory harness and ran the wires with the rest of the harness. But I had my truck torn down to the bones and plenty of access to the harness. You can simply run the two wires directly across to the PCM if you want to, or wrap them around the engine four-times. Just get them over to the PCM.

At the PCM, we will be working with the red plug. There are three little tabs that hold the connector together, press them in and the plug will open up and loosen up the wires enough to work with them. You will also see that each hole is numbered.



In the first picture above, you will see a little white locking tab on the side of the red plug. There is a tab on both sides that will need to be pressed in, this will release the pressure on the cover and allow you to pull it off. Beware; it's got a double-vained seal around it, and years of dirt/dust build up holding in it place. Don't be surprised if you have to get an extra pair of hands to hold the tabs down while you gently pry the red cover off.

With the red cover off, you will see a series of circular terminals and white tabs. These terminals come out a lot easier than one would think. Simply pull the white tabs back with your fingernail and it will release the lock holding the terminals in place. Personal opinion: Yes! My fingernails are black, deal with it.


This picture shows the lugs on the white tabs that lock the terminal in place. And the ridge on the terminal where the lugs sit to lock them in place.


We are looking for five wires, injectors two through six. Since injector one (black) stays in the same location. So find the following pins and pull the wires out.

Injector two (green/black) from pin 15

Injector three (pink/black) from pin 16

Injector four (blue/black) from pin 32

Injector five (black/white) from pin 31

Injector six (yellow/black) from pin 9

You should now be looking at something similar to this.


Now it's just a matter of sticking them in the new holes.

Injector two (green/black) into pin 11

Injector three (pink/black) into pin 32

Injector four (blue/black) into pin 31

Injector six (yellow black) into pin 16

By now you have realized you will need two of the round terminals for injectors seven and eight. The dealer cannot get these(or I haven't found a good part number I should say.) I have only found one place online who will sell them separately. This place is www.currentperformance.com. The terminals aren't on his website, you have to call him and ask for them specifically. He also sells the V8 pod plug if you want to get everything at once. Just be prepared for a few weeks worth of delivery time. Crimp the new terminals on and install them.

Injector seven (red/black) into pin 12

Injector eight (blue/white) into pin 9.

Double check to make sure every terminal is in the right place. Now bend the tabs back into place and give the wires a gentle tug to make sure they are locked into place. Don't worry if the tabs are a little loose, the red cover will lock the tabs into place when it's installed. With the red cover in place, give the wires another once over with gentle tugs to make sure they are still locked into place. Snap the entire plug back together and plug it in to the PCM.

Congratulations, you just modified your existing V6 harness.
Old 10-08-2010, 08:48 AM   #13
Sure why not.
 
rhygin's Avatar

 
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Re: Possible Vortec L31 sticky....

Subscribing just so I dont have to looks this up again.
Old 10-08-2010, 11:43 PM   #14
Sure why not.
 
rhygin's Avatar

 
Age: 28
Join Date: Nov 2005
Posts: 2,202
Location: Vancouver, WA
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Re: Possible Vortec L31 sticky....

If I get the 350 computer as well do I still need to reflash it? And what do i do about the extra oxygen sensors that the 350 has? This is really well done btw, thanks for the time you put into it.
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