I finally got a new engine for the K5! Its a tbi 350 out of an early 90s silverado. Since im just using the engine and keeping my original 700r4 I don't have to worry about any vss or spedo stuff right? I have done a lot of research and had planned on just getting the throttle body, harness, and ecm and stripping the harness of everything but the essentials. But since I got a good deal on a complete engine im not sure thats the best idea. the harness was just unplugged at the firewall, my 85 blazer also has a plug in the fire wall but a different socket and number of wires. Is there some kind of adapter i can get? Are any of those wires even the same? As you can probably tell im completely lost so any help would be great.
CK5
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85 305 to 350 tbi swap questions.
- Thread starter jkeys0218
- Start date
You are going to get opinions on this, I don't think any are wrong.
Mine is, go find a 1987-1991 K5, burb, or crew cab, and take the entire underhood and underdash wiring harness.
It's a pain, but that will ensure troubleshooting will be as easy as possible when/if you ever need to.
You need VSS etc., but your '85 probably already has it (has cruise? then yes). Did you get an ECM/PCM with it? Another reason I think it's better to stick with the '87-91 stuff.
Aftermarket harnesses are another option, but probably somewhat pricey. In regards to emissions, EGR and AIR are the only two I can think of that can be stripped with minimal issues, but EGR at least will trigger a CEL without having the PROM setup to eliminate it.
Mine is, go find a 1987-1991 K5, burb, or crew cab, and take the entire underhood and underdash wiring harness.
It's a pain, but that will ensure troubleshooting will be as easy as possible when/if you ever need to.
You need VSS etc., but your '85 probably already has it (has cruise? then yes). Did you get an ECM/PCM with it? Another reason I think it's better to stick with the '87-91 stuff.
Aftermarket harnesses are another option, but probably somewhat pricey. In regards to emissions, EGR and AIR are the only two I can think of that can be stripped with minimal issues, but EGR at least will trigger a CEL without having the PROM setup to eliminate it.
Which wiring are you talking about? The '85 that isn't wired for ECM, Fuel pump, etc? Or the later one that doesn't fit the '85 body?
You'll need the CEL working, but that's part of the wiring issue. It is all wrong on the '85 or the non-R/V donor.
You'll need the CEL working, but that's part of the wiring issue. It is all wrong on the '85 or the non-R/V donor.
You mention it, but you talk about the plug to the firewall. The interior harness is what you need to power everything.
You can't just convert your '85 plug over with the new wiring, the wiring on the cab side of the connector doesn't match up, since there was no fuel pump relay, and whatever else they might have powered on the C/K body style from the fuse panel is unknown to me.
I *assume* most of the engine side wiring is separate on the C/K stuff at that point, but not all of it. You can spend time messing around trying to adapt the two different years to each other, and run into electrical problems when you try and start it, or just get an '87-91 R/V harness and spend the time swapping the wiring, but not have any problems from there on out.
Still going to have to dig into the dash to wire VSS to the ECM/PCM, run ECM power, run the wiring for the ECM, etc.
What part number is the ECM/PCM? If it's a 4L60E application, you are going to have to get the PROM re-done as well.
Not at all telling you don't do the swap, it sounds like a lot, but once you dig into it, it's not THAT complex.
Don't forget the fuel tank and sending unit/fuel pump for an 87-91 K5 either. Can get away with a non-baffled (earlier) tank, but not a real good option IMO. In-tank pump is a definite yes as well.
You can't just convert your '85 plug over with the new wiring, the wiring on the cab side of the connector doesn't match up, since there was no fuel pump relay, and whatever else they might have powered on the C/K body style from the fuse panel is unknown to me.
I *assume* most of the engine side wiring is separate on the C/K stuff at that point, but not all of it. You can spend time messing around trying to adapt the two different years to each other, and run into electrical problems when you try and start it, or just get an '87-91 R/V harness and spend the time swapping the wiring, but not have any problems from there on out.
Still going to have to dig into the dash to wire VSS to the ECM/PCM, run ECM power, run the wiring for the ECM, etc.
What part number is the ECM/PCM? If it's a 4L60E application, you are going to have to get the PROM re-done as well.
Not at all telling you don't do the swap, it sounds like a lot, but once you dig into it, it's not THAT complex.
Don't forget the fuel tank and sending unit/fuel pump for an 87-91 K5 either. Can get away with a non-baffled (earlier) tank, but not a real good option IMO. In-tank pump is a definite yes as well.
I had planned on adding all the relays and a new fuse box under the hood to power ecm, fuel pump, ect... And leave the stock one alone to continue to power everything else. I think the last numbers of the ecm were 47. Im out of town now but ill make sure when i get home. The stock motor has really gone down hill in the last month so id like to get the new one in but im going to be very limited on tine for the next few weeks. Does anyone make a carb that will bolt onto the tbi or an adapter plate. I just want something to get me buy, doesn't need to be high performance or anything. I just dont want to change the intake.
I would expect a two barrel carb would work, but a 4 barrel adapter would be a bad setup. Never seen a carb to TBI intake adapter, but never looked either.
I've gone down the road of adding another small fuse "panel" to run injection, but the amount of wiring, parts, and work necessary to get that done nicely isn't worth it IMO. If you want to improve or add things electrically now or down the road, the best overall option I know of, is to wire in one of the newer vehicles (any car after about the early 90's it seems) underhood fuse/relay centers. It would really clean up the engine bay as opposed to the multitude of wires and relays everywhere you end up with on an injection setup, along with any additional components you might want later (lights, etc).
Common early TBI ECM is 1227747 which is designed for a non-electronic transmission. Just depends on year, I don't remember when the 4L60E was introduced. I know the later ECM's are "better", but that all depends on how in-depth you are going to get on the engine and tuning.
I've gone down the road of adding another small fuse "panel" to run injection, but the amount of wiring, parts, and work necessary to get that done nicely isn't worth it IMO. If you want to improve or add things electrically now or down the road, the best overall option I know of, is to wire in one of the newer vehicles (any car after about the early 90's it seems) underhood fuse/relay centers. It would really clean up the engine bay as opposed to the multitude of wires and relays everywhere you end up with on an injection setup, along with any additional components you might want later (lights, etc).
Common early TBI ECM is 1227747 which is designed for a non-electronic transmission. Just depends on year, I don't remember when the 4L60E was introduced. I know the later ECM's are "better", but that all depends on how in-depth you are going to get on the engine and tuning.
A tbi to carb adapter wouldn't work because the carb would hit the bolt that are holding the adapter onto the intake.
I planned on a fues/relay center out of a newer vehicle like you said. Im an electrician so a little extea wiring is no big deal. Any idea how much one of these is?
Thats the right number on the ecm.
I planned on a fues/relay center out of a newer vehicle like you said. Im an electrician so a little extea wiring is no big deal. Any idea how much one of these is?
Thats the right number on the ecm.
Well, I assume it would need countersunk bolts. Don't know what the two barrel vs. TBI pattern looks like, that would factor in.
Locally, at one wrecking yard, any sort of wiring is really dirt cheap...I could walk out of there with a plastic shopping bag FULL of wiring for $20 or less. Also a good source for long runs of wire if you want to make continuous runs of wire, instead of a bunch of splices, and want to color code stuff.
Obviously cost is going to depend. I haven't checked on ebay, but you might find some on there. I kind of like sticking with GM as I can get a bit more familiar with it, than using something from Toyota, and Ford, and GM, etc. Trying to re-use some of the micro-fuse terminals and what not gets tedious, buying them new for a few cents and making your own is more enjoyable for me. If you aren't familiar, mouser.com is a very, very good source for Delphi automotive electrical components. Once you can figure out what you need.
Locally, at one wrecking yard, any sort of wiring is really dirt cheap...I could walk out of there with a plastic shopping bag FULL of wiring for $20 or less. Also a good source for long runs of wire if you want to make continuous runs of wire, instead of a bunch of splices, and want to color code stuff.
Obviously cost is going to depend. I haven't checked on ebay, but you might find some on there. I kind of like sticking with GM as I can get a bit more familiar with it, than using something from Toyota, and Ford, and GM, etc. Trying to re-use some of the micro-fuse terminals and what not gets tedious, buying them new for a few cents and making your own is more enjoyable for me. If you aren't familiar, mouser.com is a very, very good source for Delphi automotive electrical components. Once you can figure out what you need.
Thanks ill check it out. And i can get 20' scrap pieces of wire from work for free. Are there any particular vehicles i should stay away from when looking for a fuse/relay box? Ill stick with gm for sure
You can rewire that harness to be stand alone but it is a lot of work. I've done it many times.
There is a two barrel carb to TBI adapter made by holley.
For the cheap junk yard relays and parts look at some late 80s to 90s V6 cars and you'll find banks of 4-5 relays, trucks have inline fuses and power distribution along with fuse-able links. With underhood ECM, relays, fuses and a complete harness I have about $75 into this one and it's wired for two electric fans because the ECM will control them.
There is a two barrel carb to TBI adapter made by holley.
For the cheap junk yard relays and parts look at some late 80s to 90s V6 cars and you'll find banks of 4-5 relays, trucks have inline fuses and power distribution along with fuse-able links. With underhood ECM, relays, fuses and a complete harness I have about $75 into this one and it's wired for two electric fans because the ECM will control them.
The 90's full size Cadillacs have a decent panel, but the one I grab is fuses only. Only thing I don't like is that it uses a goofy bracket and way it is retained to the bracket. That can be worked around with some work. Might be better options out there, I haven't spent a ton of time looking at other makes/models. The full size 90's Cadillacs seem to be this 'yards forte.
If you can find something that integrates the relays and fuses, and isn't a one piece design that will be hard to retrofit, that's what I'd go with. Better to have more fuses and relays available than you need, than the other way around. I went with a small auxiliary fuse panel initially, but without being able to gang the power feeds, yet individually fuse the outputs (like the OE panels do) you end up with just as many wires going in as you do going out, which is messy. With an underhood OE panel, you can make a relatively short run of a heavier gauge wire, and if ignition power is needed, or switched headlight, or whatever, you can simply via relay, make a section of the fuses "hot" at the appropriate time.
As an electrician I'm sure you have a good idea of what you need to do, I didn't really do much electrical until I got into the fuel injection retrofit, and made some mistakes along the way that I won't make again when I inject my car.
If you can find something that integrates the relays and fuses, and isn't a one piece design that will be hard to retrofit, that's what I'd go with. Better to have more fuses and relays available than you need, than the other way around. I went with a small auxiliary fuse panel initially, but without being able to gang the power feeds, yet individually fuse the outputs (like the OE panels do) you end up with just as many wires going in as you do going out, which is messy. With an underhood OE panel, you can make a relatively short run of a heavier gauge wire, and if ignition power is needed, or switched headlight, or whatever, you can simply via relay, make a section of the fuses "hot" at the appropriate time.
As an electrician I'm sure you have a good idea of what you need to do, I didn't really do much electrical until I got into the fuel injection retrofit, and made some mistakes along the way that I won't make again when I inject my car.
There's actually 2 12 volt always and one Key on 12 volt, besides other 12 volts that come into system like injectors. Here's the wiring diagrams... one by one and peck away at it.
http://coloradok5.com/forums/showthread.php?t=302678
Tip! Use your wire to distributor to a relay to turn system on.
http://coloradok5.com/forums/showthread.php?t=302678
Tip! Use your wire to distributor to a relay to turn system on.
Much of it is going to depend what you decide to add later for electrical. There isn't a WHOLE lot just for the injection (and IIRC, it takes less than 15A total to run the injection/motor), but you might want to do things like ignition 12V via relay and feed things like the ECM off of it.
Then later on, if you want to run dual electric fans, headlight relay mod, driving lights, light bar, whatever, you'd have the extra capacity.
If the truck wiring is already that messed up, you might just consider re-wiring the whole thing and getting rid of the stock fuse panel? Judging by how few fuses are really on the stock fuse panel, and how many the fuse/relay centers offer, I would think it to be relatively simple to do.
I think stand-alone vs. integrated is somewhat over thought. As an electrician, some system complexity isn't likely to bother you. IMO stand-alone setups are normally geared towards people who are either afraid to learn what wire does what, or are retrofitting it into a vehicle that is far harder to inject than one of our trucks.
If it was truly standalone, then you'd be talking a separate fuse panel in any case, which isn't really making things more simple IMO. And when talking about these trucks, for a basic install where someone isn't intending to add a bunch of electrical stuff in the future, for the effort, an '87-91 R/V donor wiring harness makes as much sense as anything else. Just depends what you see in the future for the electrical system.
Then later on, if you want to run dual electric fans, headlight relay mod, driving lights, light bar, whatever, you'd have the extra capacity.
If the truck wiring is already that messed up, you might just consider re-wiring the whole thing and getting rid of the stock fuse panel? Judging by how few fuses are really on the stock fuse panel, and how many the fuse/relay centers offer, I would think it to be relatively simple to do.
I think stand-alone vs. integrated is somewhat over thought. As an electrician, some system complexity isn't likely to bother you. IMO stand-alone setups are normally geared towards people who are either afraid to learn what wire does what, or are retrofitting it into a vehicle that is far harder to inject than one of our trucks.
If it was truly standalone, then you'd be talking a separate fuse panel in any case, which isn't really making things more simple IMO. And when talking about these trucks, for a basic install where someone isn't intending to add a bunch of electrical stuff in the future, for the effort, an '87-91 R/V donor wiring harness makes as much sense as anything else. Just depends what you see in the future for the electrical system.
I plan on replacing all the electrical i just dont want to get into it now because i dont have the time. I think ill go with a stand alone system and then in the future when i have time ill rip out the old panel and put everything on the new one under the hood. Also while lokking at the currant panel under the dash i noticed there wasn't a fuse in the socket labeled ecm. When i tried to put one in i realized there wasn't even wires going to that one. I was under the impression that i should have an ecm for the cc carburetor that was on it. Was it feed from somewhere else in 85? And where is the ecm at in the vehicle anyway?
Trucks were kind of stupid this vintage. Are you sure your truck is CCC? All 305 trucks (to my knowledge) had ESC, which was basically spark/knock control, since they were relatively high compression (9:1) on bad heads, so prone to detonation.
I'm not sure how ESC was wired up for power. It must be on some sort of fuse, but no idea what it would be called.
AFAIK, CA trucks were the only ones that got CCC.
Now that I think about it, I wonder if 305's were even offered in CA...just guessing here, but if 305's weren't CCC, CA probably didn't allow them.
I'm not sure how ESC was wired up for power. It must be on some sort of fuse, but no idea what it would be called.
AFAIK, CA trucks were the only ones that got CCC.
Now that I think about it, I wonder if 305's were even offered in CA...just guessing here, but if 305's weren't CCC, CA probably didn't allow them.
Pretty sure. I was planning on rebuilding the carb but after running thr numbers everyone said it was a ccc and it had the sensors and wires in it. So i bought an older one and rebuilt it. Its definitely not a Ca model though.
