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Tearin' out the Lean Burn - Gots some questions...
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Author:  Rob Simmons [ Sun Nov 07, 2010 5:07 pm ]
Post subject:  Tearin' out the Lean Burn - Gots some questions...
So, I tore into my '83 D150 (318) today to help the poor thing run right again. I bought it about a month ago knowing it needed some help. I've got a couple questions regarding the wiring and vacuum lines.

Electrical:
1. There is a junction of hot wires I will affectionately call the "Hot Spider" (because there are eight hot wires joined there :lol: ) I think I can cut and discard half of them - maybe five. The ones I think I can get rid of are:
A. Lean Burn computer
B. Carb #1
C. Carb #2
D. Emissions module on passenger fender

Maybe - Oil sender pod at rear of engine that has three wires going to it (I will likely replace the sender with another one for an aftermarket oil pressure gauge).

The ones I assume I need to keep are:
A. Bulk head connector
B. Alternator
C. Coil (+)
Maybe (see above)

There is one lone wire (black with a yellow tracer) that goes into the top left corner of the bulk head connector that I believe went to a hot wire, but I'm not sure. Is that wire for the "run" circuit?

The other basic wiring I will hook up according to the HEI swap thread. Am I missing anything?

Oh yeah, I couldn't find any ballast resistor! With all the fuss about bypassing the thing when you go to HEI, why ain't this thing got one? :? :lol:

The AC on this truck was removed, so I plan to leave that wiring out for now as well.

On the vacuum line side of things there are so many that I need some guidance on what the bare minimums are. There are/were nearly a dozen different vacuum ports. Many of them were either just left unhooked or in one case they were plugged with wood screws! :shock:

So, to get down to the basics I think the only ones I really need are:
A. Distributor advance canister
B. Carb

Should I keep the EGR valve hooked up or plug it?
Charcoal canister was not connected.

What else?

I thought I had the Chilton manual for the truck, but it is for trucks up to "82...

Thanks!
Author:  Charrlie_S [ Sun Nov 07, 2010 5:19 pm ]
Post subject: 
Just a couple of quick things off the top of my head, and not haveing a diagram in front of me. If I remember correctly the oil pressure switch is also used to supply voltage to the electric boosted choke, when the engine is running.
The ballast resistor is not used with the lean burn system, the computer does its function, internally.
I would reconnect the charcol cannister.
Author:  Rob Simmons [ Sun Nov 07, 2010 5:50 pm ]
Post subject: 
Thanks Charrlie!

I forgot to mention that I have a Holley 350 CFM carb with a manual choke to replace the Lean Burn carb. I haven't checked yet to see if I can use the electric choke with the Holley carb. I think one of the wires coming from the oil pressure switch does go to the electric choke.

Also, the wires coming from the bulk head connector together in one main connector go to five places:
1. Water temp sensor
2. alternator field
3. alternator main
4. "Hot Spider"
5. white wire to a single clip (was disconnected I think...)

That one lone wire going to the bulkhead connector by itself goes into the 40 space on the wiring diagrams I can find, but the wiring diagrams all say that there is no wire going there... :?

I assume I can just leave the O2 sensor disconnected. The cat on this truck was removed.

I still remember you talking me through the basic wiring I needed to get the GodsRods Duster running after I pulled all the wires out back in 2003! :shock:
Author:  Reed [ Sun Nov 07, 2010 9:01 pm ]
Post subject: 
OK, here you go. These are for an 83 van with lean burn spark control, and O2 feedback. Your truck should be the same:

Image

Image

Image

Lean burn systems didn't use a ballast resistor. HEI is just a much more reliable and stable ignition system that provides better spark and dwell control.

(1) The "hot spider" is most likely one of the main power supply breakouts. Much of the wires you can snip off and discard, especially if you are not retaining the carb with its idle stop solenoid and bowl vent valve.

(2) Black with yellow tracer is most likely the coil (-) wire.

(3) If the rest of the EGR system is present and functioning, you might want to keep it since it allows you to run more timing advance. But most people just disconnect it and plug it.

(4) The (+) feed that goes to the oil pressure sending unit does supply the power to the electric choke assist.

(5) I second the reconnection of the charcoal canister.

(6) Yes, you can disconnect the O2 sensor, but that is a perfect spot for a wideband O2 sensor which would greatly aid in tuning the carb.


The easiest way to swap in an HEI ignition on a vehicle that had lean burn is to use the existing wiring. The (-) coil wire stays the (-) coil wire, the (+) feed for the HEI unit can be the (+) coil lead (use a relay, though, to get full battery voltage), and you can use the existing wiring going to the lean burn distributor to attach it to the HEI unit. There, done, half hour tops. It is actually easier to convert a lean burn car to HEI than it is to convert a points car.
Author:  olafla [ Sun Nov 07, 2010 9:55 pm ]
Post subject: 
Hi Rob, maybe a stupid question as I never had a lean burn setup myself, but aren't those lean burn distributors without mechanical advance also? Do you perhaps need to replace the whole dizzy with an older one as well?

Olaf.
Author:  Reed [ Sun Nov 07, 2010 10:15 pm ]
Post subject: 
Quote:
Hi Rob, maybe a stupid question as I never had a lean burn setup myself, but aren't those lean burn distributors without mechanical advance also? Do you perhaps need to replace the whole dizzy with an older one as well?

Olaf.
Yes, you do. You need to get an electronic ignition distributor with mechanical advance and vacuum advance.
Author:  coconuteater64 [ Mon Nov 08, 2010 12:29 am ]
Post subject: 
Check your charcoal canister. Mine had nothing in it; all of the activated charcoal got either sucked into the carb or just fell out. The carb was full of this stuff when I rebuilt it. If the canister is in good shape, I recommend a cheap inline fuel filter between it and the carb to prevent this potential disaster. It won't hurt anything to leave it hooked up if it is in good shape.

I suggest the HEI conversion. I love it.
Author:  Rob Simmons [ Mon Nov 08, 2010 5:41 am ]
Post subject: 
Thank you Reed! Those diagrams really help. I will get back over there one evening this week (or maybe Veteran's Day) to fiddle some more.

I want to discard all of the wiring that I can. It certainly cleans up the engine compartment.

Coconuteater64, I will check and re-connect the charcoal canister (with a filter).

Olaf, I didn't mention that I do have another distributor with vacuum advance to replace the Lean Burn dizzy.

I have all of the parts needed for the HEI conversion. Just need to verify the wiring and vacuum stuff.

I was thinking that the O2 sensor provision would be great for a wideband at a later point as well.

Thanks everyone for your replies!
Author:  Rick Covalt [ Mon Nov 08, 2010 1:18 pm ]
Post subject:  Distributor
Hang on to your Lean burn Dist. It has a good application for some people running the programable MSD ignition. Ryan has one on his Dart


Rick
Author:  Rob Simmons [ Mon Nov 08, 2010 2:46 pm ]
Post subject: 
Hey Rick! Thanks for the "Heads Up". I won't turn it in for the $10 core charge after all. :D

Hey Reed,

You wouldn't by chance have the vacuum diagrams to compliment the wiring diagrams do you?

I'm gonna swing back by the garage on the way home so I can re-trace these wires. That lone wire going into the 40 slot on the bulk head still has me confused. :? I'm almost certain that it was soldered into a junction with other hot wires, but it could have been done by a previous owner.

I've found all sorts of creative wiring. S/he really liked extra ground wires (I've found four extra ground wires added to various places) I've also found two hot wires that came off the battery positive terminal and just went to nothing. One ran across the engine compartment along the passenger frame and was just wrapped around the ground strap that goes between the cab and bed with no termination point! I'd be interested to know what some of these things were added for.

It's like a treasure hunt to find and eliminate past offenses to this poor truck.
Author:  olafla [ Wed Nov 10, 2010 11:39 pm ]
Post subject: 
Here are some links, if they can help:

Gm Hei Module Conversion Troubles

You probably read this, but anyway...
HEI Electronic Ignition Retrofit How-To

Olaf
Author:  Reed [ Thu Nov 11, 2010 8:23 am ]
Post subject: 
Quote:
Hey Reed,

You wouldn't by chance have the vacuum diagrams to compliment the wiring diagrams do you?
The only real vacuum hose system is the EGR system. Other that that, there is just the OSAC and the charcoal canister hoses.
Author:  olafla [ Thu Nov 11, 2010 5:07 pm ]
Post subject: 
The loose wires you found, are probably for some kind of relays, for extra driving lights/fog lights, or whatever.

If the cables are big enough, you can use it to feed a relay for the HEI module. See the HEI link I posted earlier, and you see pictures of the voltage drop through the original cables.

When checking all other things, unscrew all the big engine to chassis ground cable connections, clean the faces with a steel brush, and check for good contact. Always the first spot to check if you ever have electrical trouble!

Olaf.
Author:  Rob Simmons [ Fri Nov 12, 2010 5:45 am ]
Post subject: 
I spent some time yesterday fiddling on the truck. I stopped by a local salvage yard and grabbed a heat sink out of a van. Every single module I found was different, so I just made my own crimp fittings.

All of the wiring is back in now (minus all of the Lean Burn stuff).

I still need to re-connect the hot wire going to the oil sending unit. I had snipped that one thinking I wouldn't re-use it. :roll:

Question on the wiring diagram: I was thinking that the lone wire going into the bulkhead went into the #40 cavity, but I might be reading it backwards. All wiring diagrams say that #40 cavity is empty. The #35 cavity at the opposite top corner indicates a black wire with a tan tracer that goes into the Lean Burn computer. I'll go back over the weekend and compare locations of other wires to see if indeed I was reading the bulkhead diagram backwards. :roll:

I'd like to blame being away for 6 years as the reason for my ignorance, but actually I just ain't that smart.

I started to install the 350 CFM carb, but didn't get finished before I had to call it a day. I'm not satisfied with the adapter hardware, so I'll mess around with that this weekend.

I need to get the truck running this weekend so I can back it out of the garage and out of the way. I've got household goods that have been in storage for 6 years being delivered next week. Stuff like a freezer, washer, dryer, engine hoist, drill press, bench press, engine stands... All that stuff that takes up a lot of room.

Oh yeah, when I crawled under the truck yesterday to hook up the bump starter wires I noticed a nice big puddle right about where the engine and tranny mate up. :x I didn't have the heart to taste it and see if it was oil or trans fluid. It'll be a pain either way. :cry: (Just kidding about tasting it :lol: )
Author:  Reed [ Fri Nov 12, 2010 11:26 am ]
Post subject: 
I think you got it on the black/yellow wire.

Just be sure you have the four pin HEI module and not the seven pin.
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