84 Chevy Buildup

chevyracer8262 · 07-23-2008, 07:46 PM

I have a few questions that I have ideas about. First I have an 84 Chevy SWB truck that's in great shape that I'm building. I have a 91 model tbi 350w/700r4, engine wiring harness, ecm and 2 complete donor vehicles for wiring and other misc components that I would need. What I want to do is put the tbi engine and tranny into my truck. The questions I have is can I isolate the computer controlled portions of the factory harness and splice them into my existing 84 harness. If so does anyone know which wires? What I need is info on how to make the engine and tranny portion of the harness a standalone harness. Has anyone on here done this before and does anyone have any tips or information on this kind of swap. The goal I'm going for is to try to get every mpg out of this truck I possibly can. I'm not afraid of the work and I want to do it this way because I have very little money to do this project with. Here's a list of the items I have to go into the truck already a 3.08:1 12 bolt rear end, twin electric fans, full length 1 5/8" headers, full length 2 1/4" dual exhaust w/flowmaster mufflers and x pipe, underdrive/overdrive pulleys, an 02 sensor signal tuner and 14" dia x 5" tall air cleaner assy. I'm hoping to be able to get 18-20 mpg out of this truck when finished, because I had a 91 reg cab swb with this same engine with a 5 speed and 3.42:1 gears and was getting 17mpg with it.

Any help on this is greatly appreciated because my other vehicle is going down quick and I need to get this truck running asap.

Thanks, Chevyracer8262

Doktor Rocket · 08-03-2008, 02:37 PM

Dude you're in luck. I did this exact same swap in 1993 with my 1984 chevy fleetside 4wd. I bought a book from a company called JTR. They are in Pleasanton Ca. It tells you almost exactly what you need to do to make the swap. If you would like more information I'll be lurking on the blog. The swap has gone through 7 years with me and another 7 with my oldest son. Now my youngest son is driving it. Get 18+ mpg with the tbi.

chevyracer8262 · 08-27-2008, 05:28 AM

Ok I've gotten the engine running, my next question is the drac. I've already gotten the electric speedo and also info and on how to modify the DRAC so i can have proper speed reading's with my setup. The only issue I have now is the same issue I've been fighting from the start is that I realy need a wiring diagram for the van that the parts came from. Does anyone know where i can get a copy of the wiring schematics for an 89' Chevy G20 van? Or does anyone know the wiring hookup for the DRAC module?

Thanks, Chevyracer8262

75K30 · 08-27-2008, 05:49 AM

More can be found here:
AutoZone.com | Vehicle Selection - Year

hotrodpc · 08-27-2008, 09:56 PM

How the HeII about that. You ask, and in 21 minutes later you receive even before 5am. Gotta love the Truck Forum and its members. I just notice that many of the one timers, come here to get answers, then never repost the outcome of their project.
Sounds like a project I am interested in some day and why I looked at the thread. I have an 80 GMC that used to be a Junk Olds Diesel originally w/ Lock Up THM350C. I bought it already converted to 350 Olds 4BBL Gas engine to use the same mounts and 350C trans. It is getting tired, and I am thinking of going TBI and 700R4.

chevyracer8262 · 08-28-2008, 05:46 AM

It's not that bad of a swap, I've had the engine running since Sunday. I just have the issue with finding the wiring schematic for the drac for the electronic speedo and for proper transmission function. The main reason I chose to do this swap was because I've had 3 truck's with these tbi engines and loved them because of the simplicity and how easily modified they are, and on the other hand my uncle and my dad have givin me everything I needed to do the swap. I can make you a list of everything I needed for my swap if you want. This engine sounds great with the full length headers and 2 1/2" full dual exhaust. I've even done a few mods and custom parts along the way. I installed an Edelbrock performer 4 barrel intake, custom egr passage, added a 1/2" extension to my 02 sensor bung I welded to my pass header collector to help lean out the fuel mixture because of the larger free flowing exhaust, machined a 4 barrel to tbi adapter plate, added a 8 pos dip switch to the drac so I can calibrate the speedo to work with any tire and gear combo. It's been a very fun project and I can't wait to drive it.

hotrodpc · 08-28-2008, 07:06 AM

Check out all this info. This guy has done alot of homework on this topic. You may already have this info. His email address is included at the bottom of the page and I bet he can point you in the right direction for the schematic or at least give you the pin out where the wires go.

GM DRAC/VSSB Calibration

chevyracer8262 · 08-28-2008, 07:16 AM

Thank's that's the site I found the info on modifing the drac with the dip switch, I didn't pay any attention to the email address at the bottom.

chevyracer8262 · 09-08-2008, 05:44 AM

Well I've got my 84' running and drove it yesterday. I still have to get a few more buggs worked out but this thing is extremely fun to drive. I fired a set of 235/75/15's yesterday. But still have a few more issues to fix, like there's a tuning issue because the engine torques great in 1st gear it'll boil the tire's but when it time to shift it wants to cut out and spit back through the throttle body, but other than that the powertrain is pretty well finished. Does anyone have any ideas what'll cause that?

07-23-2008, 07:46 PM	#1
chevyracer8262 Senior Member Join Date: Jul 2008 Location: Mississippi Posts: 105	84 Chevy Buildup I have a few questions that I have ideas about. First I have an 84 Chevy SWB truck that's in great shape that I'm building. I have a 91 model tbi 350w/700r4, engine wiring harness, ecm and 2 complete donor vehicles for wiring and other misc components that I would need. What I want to do is put the tbi engine and tranny into my truck. The questions I have is can I isolate the computer controlled portions of the factory harness and splice them into my existing 84 harness. If so does anyone know which wires? What I need is info on how to make the engine and tranny portion of the harness a standalone harness. Has anyone on here done this before and does anyone have any tips or information on this kind of swap. The goal I'm going for is to try to get every mpg out of this truck I possibly can. I'm not afraid of the work and I want to do it this way because I have very little money to do this project with. Here's a list of the items I have to go into the truck already a 3.08:1 12 bolt rear end, twin electric fans, full length 1 5/8" headers, full length 2 1/4" dual exhaust w/flowmaster mufflers and x pipe, underdrive/overdrive pulleys, an 02 sensor signal tuner and 14" dia x 5" tall air cleaner assy. I'm hoping to be able to get 18-20 mpg out of this truck when finished, because I had a 91 reg cab swb with this same engine with a 5 speed and 3.42:1 gears and was getting 17mpg with it. Any help on this is greatly appreciated because my other vehicle is going down quick and I need to get this truck running asap. Thanks, Chevyracer8262

09-08-2008, 05:44 AM	#9
chevyracer8262 Senior Member Join Date: Jul 2008 Location: Mississippi Posts: 105	Well I've got my 84' running and drove it yesterday. I still have to get a few more buggs worked out but this thing is extremely fun to drive. I fired a set of 235/75/15's yesterday. But still have a few more issues to fix, like there's a tuning issue because the engine torques great in 1st gear it'll boil the tire's but when it time to shift it wants to cut out and spit back through the throttle body, but other than that the powertrain is pretty well finished. Does anyone have any ideas what'll cause that? __________________ Chevyracer8262

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08-03-2008, 02:37 PM	#2
Doktor Rocket Full Member Join Date: Aug 2008 Location: Northern California Posts: 13	Dude you're in luck. I did this exact same swap in 1993 with my 1984 chevy fleetside 4wd. I bought a book from a company called JTR. They are in Pleasanton Ca. It tells you almost exactly what you need to do to make the swap. If you would like more information I'll be lurking on the blog. The swap has gone through 7 years with me and another 7 with my oldest son. Now my youngest son is driving it. Get 18+ mpg with the tbi.

08-27-2008, 05:28 AM	#3
chevyracer8262 Senior Member Join Date: Jul 2008 Location: Mississippi Posts: 105	Ok I've gotten the engine running, my next question is the drac. I've already gotten the electric speedo and also info and on how to modify the DRAC so i can have proper speed reading's with my setup. The only issue I have now is the same issue I've been fighting from the start is that I realy need a wiring diagram for the van that the parts came from. Does anyone know where i can get a copy of the wiring schematics for an 89' Chevy G20 van? Or does anyone know the wiring hookup for the DRAC module? Thanks, Chevyracer8262

08-27-2008, 05:49 AM	#4
75K30 Senior Member Join Date: Jul 2006 Posts: 2,543	More can be found here: AutoZone.com \| Vehicle Selection - Year

08-27-2008, 09:56 PM	#5
hotrodpc Senior Member Join Date: Jul 2008 Posts: 108	How the HeII about that. You ask, and in 21 minutes later you receive even before 5am. Gotta love the Truck Forum and its members. I just notice that many of the one timers, come here to get answers, then never repost the outcome of their project. Sounds like a project I am interested in some day and why I looked at the thread. I have an 80 GMC that used to be a Junk Olds Diesel originally w/ Lock Up THM350C. I bought it already converted to 350 Olds 4BBL Gas engine to use the same mounts and 350C trans. It is getting tired, and I am thinking of going TBI and 700R4.

08-28-2008, 05:46 AM	#6
chevyracer8262 Senior Member Join Date: Jul 2008 Location: Mississippi Posts: 105	It's not that bad of a swap, I've had the engine running since Sunday. I just have the issue with finding the wiring schematic for the drac for the electronic speedo and for proper transmission function. The main reason I chose to do this swap was because I've had 3 truck's with these tbi engines and loved them because of the simplicity and how easily modified they are, and on the other hand my uncle and my dad have givin me everything I needed to do the swap. I can make you a list of everything I needed for my swap if you want. This engine sounds great with the full length headers and 2 1/2" full dual exhaust. I've even done a few mods and custom parts along the way. I installed an Edelbrock performer 4 barrel intake, custom egr passage, added a 1/2" extension to my 02 sensor bung I welded to my pass header collector to help lean out the fuel mixture because of the larger free flowing exhaust, machined a 4 barrel to tbi adapter plate, added a 8 pos dip switch to the drac so I can calibrate the speedo to work with any tire and gear combo. It's been a very fun project and I can't wait to drive it.

08-28-2008, 07:06 AM	#7
hotrodpc Senior Member Join Date: Jul 2008 Posts: 108	Check out all this info. This guy has done alot of homework on this topic. You may already have this info. His email address is included at the bottom of the page and I bet he can point you in the right direction for the schematic or at least give you the pin out where the wires go. GM DRAC/VSSB Calibration

08-28-2008, 07:16 AM	#8
chevyracer8262 Senior Member Join Date: Jul 2008 Location: Mississippi Posts: 105	Thank's that's the site I found the info on modifing the drac with the dip switch, I didn't pay any attention to the email address at the bottom.