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Vortec Engine Swap Problems 5700 350

41K views 22 replies 8 participants last post by  Sick78 
#1 ·
I have a 97 Vortec 5700 350 that I purchased out of a rolled Tahoe. I have the complete underhood wiring harness, computer and all accessories as it came out of the truck.

I have searched for information on how to make this swap simple into my 84 Suburban Hummer kit Truck. I was told that I needed about 65 psi in the fuel rails and power to four of the computer wires to make it work. After searching for several weeks at multiple sites I still have the same information I started with.

The closest information I have was in a post started in Aug 2003
http://hotrodders.com/showthread.php?s=&threadid=21533&highlight=96+vortec

Any help on this swap would be great.

I am assuming that I can use the stock fuel lines, but I will need to connect to the high pressure fuel rails with either a high pressure hose, or one of the quick disconnect high pressure fittings.
The original truck was a Diesel and had a rusty tank. I am replacing the fuel tank with a newer tank, but believe I will need to purchase an in tank fuel pump that puts out enough pressure to make the vortec happy.

This would take care of the fuel issues. The only other item is how to connect the wiring into the vortec harness. Since I am building a kit, the original suburban harness was discarded and is being replaced with a painless wiring fuse panel. This is basically a modern day street rod build. Has someone performed this swap, or have access to what wires need power on the Vortec underhood harness?

Thanks in advance for all of your assistance.
 
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#3 ·
I did not hear the engine run, but I did buy it from a reputable salvage yard I did however see the truck with the 37,000 miles prior to the engine being pulled. The computer would turn on the digital dash, but the front corner was crushed. The only damage to the engine was a cracked fuse cover and a bent power steering line.
 
#4 ·
Do you have ALL the grounds hooked up? I have never hooked up a later Vortec multi point harness but the older tbi harnesses are not always color coded correctly. I now Always hear one run first and pull the harness with the engine running and label every wire that is critical for the engine to run.

Nonetheless it sounds like you may have a ground off and GM has been tricky in that department before. On some of the tbi's they ran a brown w/black stripe(i think it was brown) wire to run the fuel pump relay. Whoa! I about lost a brain over that once;) Who was the genius that decided to run a brown wire with a black stripe as the energizer for the pump relay anyways?
 
#5 ·
I have performed a ground up restoration in building this kit. I stripped the frame and painted prior to mounting the body. I am now reinstalling the fuel and brake lines. Once this is complete I will install the engine, transmission and transfer case. I was trying to get some information up front so that when I started this weekend, I would have a plan on what is needed.
 
#6 ·
Sorry!
I was on another thread...the thread you left the link to:rolleyes:

anyways, i have done a couple of swaps and if you are able to afford the "painless" route that is exactly what I would do, buy the Painless Vortec kit and incorporate that into you current painless harness. it should be easy that way.

Like I said in a previous post, the factory harnesses are not always color coded correctly. I tried a '96 4.3 vortec with a cut harness and had problems. I went to Daryl Hickman(local Chevy dealer where I used to work) and the harness i had was color coded different than the dealer books! If your current harness is cut buy the "painless vortec" harness. If i was there i could help you but over the net i cannnot. sorry and best of luck. Please let us know how it goes!
 
#8 ·
Thanks Greg, I have sent you a PM with my email address.

NXS - I do not have a painless underhood vortec wiring harness.

As with most street rod builds, I have a new fuse panel. The underhood wiring harness and computer are stock GM. If the computer only needs four wires to receive power, I could not justify the $350 - $700 underhood harnesses that I have seen advertised. Perhaps the wiring diagram from Greg will help.

Has anyone other than Adam Mclaughlin performed one of the late model vortec engine swaps? Do you have any lessons learned?
 
#9 ·
Yea, painless is painless until you gotta read the credit card statement! lol

I cannot justify that expense either. Just as a furtue idea:

If possible start the vehicle first and cut the harness wires one by one(being very careful). When your assistant says a gauge dies mark the wire as being "oil" or whatever. When one kills the engine take a DMM and test to see if the wire was a ground or hot, mark it and reconnect it. Continue until the entire harness is cut and the install will be sooo easy becayse YOU have already marked each wire. I know it won't help you now but for future reference or anybody else thinking about doing a swap like this it could be worth(compared to painless) $350- 700.

Greg, can you e-mail that to me also? If so> nisancatron@msn.com

-Thanks guys and good luck Capps!
 
#14 ·
Very nice web site! It would have heped me a lot. I glanced at your section on the fuel system and agree with your cautions about the need for high-pressure hose.

I bought the 2 sections of factory flex that GM uses to connect the rails to the lines. I cut off the connectors that would normally go to the supply and return lines, and connected them to the steel lines that I plumbed back to the original fuel lines from the tank using high pressure compression fittings (that sounds pretty confusing, but it worked :confused: ). They weren't that expensive, and they have worked like a charm. It really helped to have the parts guys at my local Pontiac/GMC on my side.

Bluesman
 
#17 ·
I am using the 4L60E that came from the yard with the engine. Remember, I am running a 1997 VCM on a rewired 1998 engine and tranny. Actually, it works just fine. I bought a Hypertech tuner but with California premium at only 91 octane, I rarely run the higher performance tune (it pings when it shifts under a load). I do use the tuner to set the rear-end ratio, the tire diameter, and the shift points and firmness. This little truck is my daily driver and I love it. :thumbup:

How is yours coming along??

Dave
 
#18 ·
I have worked on several other projects, but not my engine. I got a little frustrated when after looking at several wiring diagrams, I began to think that the $660 Painless Wiring harness looked a lot better. When I bought the engine, I thought it was much simpler to get running since I had the factory harness and computer. However, I have a 700R4 transmission and not the electronic one that came with the engine. Several people including Painless told me that I would need to send the computer out to get it reprogrammed for the 700R4. I have the lock down kit for the converter already. After looking at the painless harness price and reprogramming the costs will add another $1200 to my engine swap. I don't know whether to give up, buy an electronic transmission or keep pouring money into it. For the past 6 months it has not been touched other than to turn the engine over. It sits installed in my truck in my shop.
 
#19 ·
That may or may not be accurate info on the 700R4. For most of its life it use hydraulic shifters. I believe it only used electronic shifters for the year before getting renamed 6L60E. Check with the folks in the tranny forum. I think you are getting bad info about reprogramming the VCM to run a 700R4.

Dave
 
#22 ·
well i wanted to do the 6.0 vortec but i already have a 97 silverado but it dose have 180,000mi on it... i wonder if i could sell or trade the truck for the 6.0... my project is an 85 chevy crew cab 4x4 and i wanted to put a 6.0 vortec in it. im not sure what i want... well actually i do but it depends on cash... wich i have none :confused:
 
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