1986 Custom Deluxe computer?? Smog equipment???

[Hart_Rod]

I just bought a one owner rust free 86 SWB with 93K (305/700R4). Its a very clean truck that I don't plan on doing much to other than fixing a few small things:

heater core is leaking, replaced the temp sender, the seat needs recovered on the drivers side, I picked up a tilt for it, , had dual 50 series flowmasters exhaust put on it, I may drop it a little later on.....

One thing I have noticed about it is that it has a lot of smog stuff on it and it appears that it has a computer behind the glove box. Is the carb computer controlled? Is there a way to tune the computer? Can the smog stuff be eliminated? Should I just leave it alone and drive it? Thanks for the input.

[86c20]

its not a ecm for the carb its for the dizzy. trust me when i say this. replace the dizzy and leve that unhooked. you will never find one that works when that one dies and if you do. big money. form what i was told it has to do with adj the timing for smog crap.

[Slammed84]

Nice truck! Famous last words " I don't plan on doing much to it"

[Liberty]

I actually have that same exact computer unhooked in my 82 C10.
The truck originally had a 305 but the PO swapped it out for a 350.

If you ever need a spare ESC, I'll let you have it.
That being said, I have no idea if mine actually works.

[1974ChevyC30]

As said above, the dizzy is computer controlled. The ICM changed from a 4 pin design to a 5-7 pin design. With the 5 pin design, it included a knock sensor but still have mechanical controls. With the 7 pin design the mechanical controls were done away with and became completely computer controlled. Someone correct me if I'm wrong.

[1970pelle]

I currently have a 86 C20 5.7L with a 4bbl. And had a 86 C10 with the same power train. I removed everything in about 2 hours. There was no cutting, ripping, tearing stuff. I didn't have to butcher anything up. Everything unbolts or unclips. The wiring harness is separate from the trucks main harness.

I called it the emissions harness, it comes in to the engine compartment just above the passenger side valve cover. I'm describing this with my knees touching the front bumper. I started out by unplugging everything that is connected to this harness. Then I removed the component or senor if possible.
I also removed the A.I.R pump and all its plumbing and rubber hoses. Plugged the exhaust manifolds for now, to be updated later on. I removed the ECM from behind the right mid center dash. And removed the harness as well. I took the big groment off the harness so I could reuse it. I passed my new gauges lines through that hole left there from the harness. I made the hole smaller by inserting a piece of 3/8 hose in the hole first. Then when all lines where finished being run, sealed everything with a sealer(black)
For the Distributor I bought a brand new one from Summit and dropped it right in. But if your truck has a distributor with a vacuum advance you can use the one already there. There is a post some where that tells which wires need tied together.
Piece of cake and it opens up the engine compartment, so you can see what your doing.

Ken

[Hart_Rod]

Originally Posted by 86c20

its not a ecm for the carb its for the dizzy. trust me when i say this. replace the dizzy and leve that unhooked. you will never find one that works when that one dies and if you do. big money. form what i was told it has to do with adj the timing for smog crap.

Thanks!

Originally Posted by Slammed84

Nice truck! Famous last words " I don't plan on doing much to it"

. I have plenty of other projects, I bought this truck for Home Depot runs, .

Originally Posted by Liberty

I actually have that same exact computer unhooked in my 82 C10.
The truck originally had a 305 but the PO swapped it out for a 350.

If you ever need a spare ESC, I'll let you have it.
That being said, I have no idea if mine actually works.

Thanks for the off!

Originally Posted by 1974ChevyC30

As said above, the dizzy is computer controlled. The ICM changed from a 4 pin design to a 5-7 pin design. With the 5 pin design, it included a knock sensor but still have mechanical controls. With the 7 pin design the mechanical controls were done away with and became completely computer controlled. Someone correct me if I'm wrong.

Thanks!

Originally Posted by 1970pelle

I currently have a 86 C20 5.7L with a 4bbl. And had a 86 C10 with the same power train. I removed everything in about 2 hours. There was no cutting, ripping, tearing stuff. I didn't have to butcher anything up. Everything unbolts or unclips. The wiring harness is separate from the trucks main harness.

I called it the emissions harness, it comes in to the engine compartment just above the passenger side valve cover. I'm describing this with my knees touching the front bumper. I started out by unplugging everything that is connected to this harness. Then I removed the component or senor if possible.
I also removed the A.I.R pump and all its plumbing and rubber hoses. Plugged the exhaust manifolds for now, to be updated later on. I removed the ECM from behind the right mid center dash. And removed the harness as well. I took the big groment off the harness so I could reuse it. I passed my new gauges lines through that hole left there from the harness. I made the hole smaller by inserting a piece of 3/8 hose in the hole first. Then when all lines where finished being run, sealed everything with a sealer(black)
For the Distributor I bought a brand new one from Summit and dropped it right in. But if your truck has a distributor with a vacuum advance you can use the one already there. There is a post some where that tells which wires need tied together.
Piece of cake and it opens up the engine compartment, so you can see what your doing.

Ken

Good write up Ken. How does it run after you did all of that?

[1970pelle]

My current truck run pretty good. It took a little playing with the feedback carb to get a base idle. One issue I'm fighting is my engine is very tired, due for a rebuild or replacement.
My last 86 C10 feedback carb had been running so lean it had backfired once in it's past and cracked the carb base. I chased a low vacuum reading at idle till I change out the intake manifold and carb. Then I found the bad Carb.
But I'm planning on dumping this carb and intake when I repower the truck soon. I would suggest getting rid of the feedback carb to one you can adjust better for your new set up.(exhaust,ignition)

Ken

[Hart_Rod]

Originally Posted by 1970pelle

My current truck run pretty good. It took a little playing with the feedback carb to get a base idle. One issue I'm fighting is my engine is very tired, due for a rebuild or replacement.
My last 86 C10 feedback carb had been running so lean it had backfired once in it's past and cracked the carb base. I chased a low vacuum reading at idle till I change out the intake manifold and carb. Then I found the bad Carb.
But I'm planning on dumping this carb and intake when I repower the truck soon. I would suggest getting rid of the feedback carb to one you can adjust better for your new set up.(exhaust,ignition)

Ken

How do you adjust the idle? I think my choke is staying partially closed causing it to idle to high.

[1970pelle]

Treat the carb like any Q-jet. Is the electric choke thermostat getting 12 volts when the key is on ? There is a fuse for that under the dash. And do you have vacuum to the choke pull off ? Take a look because they ran the vacuum to the pull of through a delay valve and all the way around front of the carb. I went from the manfold port in back of the carb. That sticks up from the intake.I can take a pic here .

Ken

[Hart_Rod]

Originally Posted by 1970pelle

Treat the carb like any Q-jet. Is the electric choke thermostat getting 12 volts when the key is on ? There is a fuse for that under the dash. And do you have vacuum to the choke pull off ? Take a look because they ran the vacuum to the pull of through a delay valve and all the way around front of the carb. I went from the manfold port in back of the carb. That sticks up from the intake.I can take a pic here .

Ken

A picture would be great, thanks!

[1970pelle]

Here you. Now I have to say first, I haven't done anything but the bare basic's to get this truck running. By far it isn't done or even close to be even started on. Its a drive to soccer & track practice. To watch my boys. I have two bike build going, then truck build time.
Anyway back to trucks. Its easy to see what I plugged and what I used. Please ask any questions and I'll try to my best to help.

Ken

[Hart_Rod]

Will do, thanks!

[MalibuSSwagon]

Well this is odd. When I got my 86 C10, it still had the distributor and little computer, but someone had deleted the EGR, EVAP system, and maybe AIR. It had manifolds with no air fittings. But here's the thing, it had a harness going into the cab with just wiring for the distributor and knock sensor. No wires had been pruned or removed from this harness. Also distributor had a vacuum advance. Very weird. I removed all this stuff when I converted to TPI but kept the ECU distributor and harness.

[1970pelle]

Not really. Remember my truck is a C20 which changes its CARB requirements if that's what you call it. Because of vehicle weight. My 86 C10 I had before was much like Hart Rod's truck. And I used the OEM Dist after a update till the day I sold it. I swap out the Vacuum advance to a adjustable one, new module, spring and weight kit. Saved me a few bucks.
For sure I dumped the feedback Q-jet as soon as I could. Either go with an old non feedback Q-jet or a new aftermarket carb or fuel injection.
I know some will moan over this, but I hate Q-jets. With my Mopar back ground
I'm a AFB guy all day long. When Dodge used the Q-jets on there trucks and ramchargers, motorhomes in the 80's. I had my fill of sorting them out. Give me a Thermoboog or a AFB and I'm in heaven. Sorry I saw a Duck.

ken

[jeremybadeker]

Does anybody happen to have a 2 pin solenoid for the 86 feedback carb, or know where to get one?

[1970pelle]

Originally Posted by jeremybadeker

Does anybody happen to have a 2 pin solenoid for the 86 feedback carb, or know where to get one?

I'm looking to see if I still have any take off carbs. Will let you know asap.

Ken

[jeremybadeker]

Originally Posted by 1970pelle

I'm looking to see if I still have any take off carbs. Will let you know asap.

Ken

I got lucky and found one local. Thanks though!

[Hart_Rod]

Gonna have to mess with the carb this weekend. I had dual exhaust with an H pipe put on last weekend. Now if you are sitting in gear and REV it up, when you let off the gas it backfires. Any suggestions to what might be the problem? I've gotten spoiled by the EFI stuff...... . I'm pretty sure it is running to rich, as I can smell gas from the exhaust. Thanks for the help.

[Hart_Rod]

Bump

[donut]

It could be running rich, lack of timing, stretched timing chain throwing everything wonky...
Old '86, 1/2 to I had years ago I had swapped the distributor and carb to an older model and took the ecm out of the equation. (years ago, as in pre-internet.)