1988 350TBI in 1977 non TBI

[Sander]

Hi from Europe to you all,

I found a 1988 K5 for sale that was all rotten through, including the chassis. But it had a very smooth running 350TBI in it. I made a bid on the engine alone and the guy made me wait for any bidders on the whole wreck. ("wreck" being my opinion, "nice start for restoration" was his). When he was tired of waiting (his story, but I think he discovered that it was a wreck after all) he decided to go for my bid. Problem is, he pulled it out for me and delivered the engine in the 1st crate, the TH700R4 with the NP208 and the drive shafts in the 2nd crate and the 3rd crate was filled up with pretty much all the cables, computers and modules of the entire Blazer. What I wanted was pulling it all out myself and labeling everything. I made a deal that I payed half now and the other half when I got it running.

Now after this rather long story (who made it this far?) here is my question. Does anyone have full schematics (preferably) or TBI schematics of a 1988 K5 Blazer. I want to put the engine in my 1977 K5 blazer. I already put a cable kit in the TH700R4 to use that without a computer.

Thanks in advance.

 

[lectric80]

I don't have the complete schematic, but there are plenty of threads where people have done similiar things. Most of the harness is not required, but the computer stuff is. Everything related to the computer can only plug in to one location. It should be pretty easy, but since I haven't done it to mine yet, I can't say for certain. Try searching the forum, or if you can't try looking through for anything TBI swap related.

 

[70jimmy]

I fust did a 93 TBI into a 70 using Howell harness and computer etc. I ordered the manual with it that has the scematic for $12.00.

Not sure if it would be the same or not.

It might be worth it to get a manual, helps with engine codes anyway.

 

[dyeager535]

There are a few threads here that have links to GM wiring diagrams. (Search, if you can't find them, post up, I think I can find them, although I think I did post the link in at least one thread) You can use any '87-89 R/V wiring diagram for the most part, realizing that of course different bodies may have slightly different wiring for things like interior lighting, etc.

You can also use '90-91, but a fair number of things changed with the electronic speedometer, and you'd want to be familiar with the '87-89 wiring before trying to use a '90-91 schematic.

Your best option is to transplant the entire interior harness in my opinion, since the '77 panel isn't designed to support injection. You can work around that, but if you've got the right (newer) harness, use it. You've paid for it anyways, no? Might as well get the transmission back under control too, although I don't believe leaving the TCC connector for the trans disconnected will throw any trouble codes. The other huge issue with trying to cobble together wiring is that no troubleshooting guide or assistance based on how things SHOULD be, is going to work. I had to add a bunch of wiring when I converted to TPI, but I made sure to use the right color of wire at the right locations according to the manual, and you can be darn sure that has saved me some major headaches over the years. If I could have swapped the whole panel (like you can) I would have, as I had to add in another fuse panel, all the requisite wiring, and so on, which is already on an EFI panel.

Not having dealt with older instrument clusters, you could also swap instrument clusters to get the VSS working, along with your check engine light. It may seem daunting at first, by the time you are done, you will know what every wire does, and where it goes.

 

[Sander]

Okee. I am still figuring out all the wires and I think I have a aftermarket ECM and a stock ECM together. I'll make some pictures over the weekend and post them here together with some questions. What I think is that I can completely get rid of the stock one but they are connected together with 2 wires. I'm wondering if you guys can tell me from the photo's what those wires are for and if I can get rid of them.

 

[southernspeed]

Post the pics and we'll see if we can figure them out but when I put a '90 engine in a '78 I used a Painless Wiring harness. It has everything you need including factory tech support! Well worth the money in my opinion.