Hello im new to this whole building vehicles thing (im 18) and i have a 94 gmc k1500. I pulled the motor and found i need to have it bored or replaced. I would like to buy a crate motor but most the mid HP (290-370) are vortec heads and intakes. I was wondering if i could switch to a vortec throttle body. (Or however it atomizes fuel and air) and just chip my tbi computer or would i need a vortec computer and fueling system
Dawsondan
Your 94 is Throttle Body Injected (TBI) engine, using Swirl Port heads and most likely a flat tappet cam of about 160 degrees intake and 170 exhaust duration at .050 inch of lift. Maximum lift is some where under .4 inch.
You can adapt the TBI system to a 96 up to about 2002 L31 Vortec with an aftermarket 4 bbl intake with a carb to TBI adapter. You will need to make modifications to the TBI sensors to fit the mountings of the Vortec style bolt pattern.
The Vortec cam is hotter with about 195 degrees intake and 206 exhaust and is a roller. The TBI system and programming usually picks this up but this cam is close to how far the computer's self learning capability goes, which is there to make adjustments for wear.
You will need to use the TBI engine's distributor and be sure it has a Melonized gear on the shaft. Same for coolant pump but both engines use the same serpentine belt system. A caution on the TBI pump to Vortec block is the coolant bypass passage on the right side pump horn. This will be present on the TBI pump but may or not be present on the Vortec block. If on both no problem, if not on the block, then the pump passage should be tapped and closed with a screw plug. This can be a pipe bolt thread plug whichever suits your tools.
I like to replace the plastic Vortec timing cover with the older metal unit which fits, you can tap the block for the missing bolts if desired.
The Vortec uses an external EGR plumbing. If you use the Vortec exhaust manifolds the necessary fittings will be there, if you use headers you may need to weld a fitting or fitting boss onto the header.
If an automatic the trans is a computer controlled 4L60E for standard duty trucks or a 4L80E for heavy duty trucks. Either requires the computer to operate. You need to get under to see what you got if you don't have the original installtions list for your truck.
Your truck's fuel system and computer will not support the EFI system that is part of the L31 Vortec's original design. You can keep your TBI or convert to carb with the existing system but need to add some gadgetry to the carb to run the transmission in the form of an addon Throttle Position Sensor (TPS).
All in all not a difficult swap but does require attention to some details.
Bogie
You can adapt the TBI system to a 96 up to about 2002 L31 Vortec with an aftermarket 4 bbl intake with a carb to TBI adapter. You will need to make modifications to the TBI sensors to fit the mountings of the Vortec style bolt pattern.
The Vortec cam is hotter with about 195 degrees intake and 206 exhaust and is a roller. The TBI system and programming usually picks this up but this cam is close to how far the computer's self learning capability goes, which is there to make adjustments for wear.
You will need to use the TBI engine's distributor and be sure it has a Melonized gear on the shaft. Same for coolant pump but both engines use the same serpentine belt system. A caution on the TBI pump to Vortec block is the coolant bypass passage on the right side pump horn. This will be present on the TBI pump but may or not be present on the Vortec block. If on both no problem, if not on the block, then the pump passage should be tapped and closed with a screw plug. This can be a pipe bolt thread plug whichever suits your tools.
I like to replace the plastic Vortec timing cover with the older metal unit which fits, you can tap the block for the missing bolts if desired.
The Vortec uses an external EGR plumbing. If you use the Vortec exhaust manifolds the necessary fittings will be there, if you use headers you may need to weld a fitting or fitting boss onto the header.
If an automatic the trans is a computer controlled 4L60E for standard duty trucks or a 4L80E for heavy duty trucks. Either requires the computer to operate. You need to get under to see what you got if you don't have the original installtions list for your truck.
Your truck's fuel system and computer will not support the EFI system that is part of the L31 Vortec's original design. You can keep your TBI or convert to carb with the existing system but need to add some gadgetry to the carb to run the transmission in the form of an addon Throttle Position Sensor (TPS).
All in all not a difficult swap but does require attention to some details.
Bogie
Money spent wisely on that truck will be with an LS based engine.. Tug one out of the Junkyard for $2-500 and you'll be making 325ish hp when it's in and running... Grab the engine and an ECU, and then you can buy a pre done standalone harness for $300 and then flash it yourself for $50
A 5.3L out of a '99-2003 will have a cable throttle that will hook right up. Your transmission will work and everything.. You'll need a $30 pair of LS mount adapters
A 5.3L out of a '99-2003 will have a cable throttle that will hook right up. Your transmission will work and everything.. You'll need a $30 pair of LS mount adapters
I have a 94 k1500. I lost track this is around my 14th or so TBI 5.7.
These engines are dogs. But they run forever I get around 230 to 330 out of them as drivers. They are about as simple of a fuel injection setup as your going to find. They will run with bad parts ie a bad IAC or TPS.
Best part about TBI is that they are dirt cheap to replace. You can find a good air filter to oil pan replacement in the 200k range for around $400 easily. Pull out the old engine save all the good tbi parts bolt in the new engine and run it for another 3 to 5 years.
If you go up to $800 you can often find one with vortec heads and the tbi intake already on with the old tbi setup making it a plug and play thing.
They are cheap, dumb, underpowered engines. For the money they make more sense then dropping $2000 in all the little things to move up to a vortec 350 engine for that meager hp bump.
These engines are dogs. But they run forever I get around 230 to 330 out of them as drivers. They are about as simple of a fuel injection setup as your going to find. They will run with bad parts ie a bad IAC or TPS.
Best part about TBI is that they are dirt cheap to replace. You can find a good air filter to oil pan replacement in the 200k range for around $400 easily. Pull out the old engine save all the good tbi parts bolt in the new engine and run it for another 3 to 5 years.
If you go up to $800 you can often find one with vortec heads and the tbi intake already on with the old tbi setup making it a plug and play thing.
They are cheap, dumb, underpowered engines. For the money they make more sense then dropping $2000 in all the little things to move up to a vortec 350 engine for that meager hp bump.
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