Anybody know what this vacuum part is or does?

[DonFitzwater]

This component is mounted in the drivers side fender of my 1986 W150/318 truck. It appears to be some sort of electrical device as it has two connectors and a total of 20 wires that plug into the connections. There is a vacuum line that attaches to the gold “dashpot” looking part. I have no idea what this thing is.....engine is carbureted and NOT injected.

 

[Wayne M.]

Don, that is definitely the spark computer aka ESA “Electronic Spark Advance” aka “Lean Burn” for the engine. Is it still hooked up and working?

 

[DonFitzwater]

I don’t know....there is a standard distributor in the engine (non-breaker points type) and the regular old ignition module mounted on the firewall. How do I get rid of the ESA?

 

[DonFitzwater]

I did some digging. This is definitely an ignition component but what’s strange is that most of the information I could find details a carburetor with a mixture controlling solenoid. My truck had a simple 2 bbl carb with the only electrical component being a fast idle solenoid. So the thing for me to figure out is do I hook up the vacuum line to the LB or not? Seems like I need it as there isn’t a mechanical advance or a vacuum advance on the current distributor. I’m also thinking about installing a new Mopar distributor kit to eliminate the LB all together.

 

[Tuesdak]

If it ain't broke don't fix it. Do you have to pass emissions? Fake the vacuum line routing to it if you do. Why are you working on the truck?

You really need to know if it's still has it's wires into the carb and to the point and purpose: distributor. It may have already been converted to a conventional ignition, HEI or otherwise. If it hasn't, well, these "first" primitive systems were a flow chart of did disconnecting this sensor change RPM by 50 RPM? Then volt meter hell. Vacuum lines rotting off are a good place to start. No wonder they were converted back to old school ignitions in the day or upgraded today. Last one I worked on was a K car 4 banger and the intake manifold bolts were loose causing the problem. (I still recall mechanics looking at GM's coil in cap HEI in the early 80's and not wanting to touch it.)

https://www.allpar.com/mopar/lean-burn.html

 

[Tuesdak]

I did some digging. This is definitely an ignition component but what’s strange is that most of the information I could find details a carburetor with a mixture controlling solenoid. My truck had a simple 2 bbl carb with the only electrical component being a fast idle solenoid. So the thing for me to figure out is do I hook up the vacuum line to the LB or not? Seems like I need it as there isn’t a mechanical advance or a vacuum advance on the current distributor. I’m also thinking about installing a new Mopar distributor kit to eliminate the LB all together.

IMO the kit is a very good idea as it sounds like it's already broke with the vac line off. the kit is modern vs. the Primitive hard to troubleshoot LB Ignition System. Seriously it's a hard question to even answer if LB is even working properly on a good day. This is assuming it already hasn't been converted. A good look at the current dist and where it's connected is in order.

 

[Wayne M.]

Don, you say there’s a ‘70’s style ignition box on the firewall? By ‘86 I’m certain they stopped using those. Everything had some sort of engine management by then. I’ve done a dozen of these conversions, and I’ve seen basic carbs used with ESA. The harness coming off the ign box, how does it blend in with the rest of the harness? The old MP conversion kit had a factory looking harness, so if it overlays everything I would say it’s a well done conversion.
Your real answer lies at the coil. Do you see any disconnected (-) wires and maybe a distributor plug or 2 laying around? Does it have a O2 sensor anywhere? If so, those might be the original ESA hook ups.

 

[DonFitzwater]

There are no tps, o2 sensors.....there are two temp senders on the intake...one with a single wire for the gauge and the two wire for the Lean Burn I’m guessing. I’ll fill you guys in on what I’m up to:

At 126k miles she was using oil and a compression test revealed low compression on 2,6 and 8. Leak down showed bad valves. I decided to yank the engine and disassemble to have a look as previous maintenance was less than desirable. Cylinder 2 had a scratch full length of the cylinder otherwise I would have re-ringed and re-bearing it with a valve job as well....I did a total rebuild, bore and hone x8 and minor head porting and valve job. I found a Quick Fuel 650 carb and Edelbrock intake along with a Hughes camshaft. It’s going to be a lightly modified 318 and thankfully, we don’t have emissions testing here any more. I’ll post a pic of the engine shortly.

 

[Wayne M.]

Nothing like a happy 318!
Fellow at work did his ‘84, and warmed it up a bit. Got these shorty headers and all. Runs great. Yank that garbage out!

 

[DonFitzwater]

Here are some pics.

 

[DonFitzwater]

The distributor only has two wires and no vacuum advance.

 

[Wayne M.]

Did you have those valve covers on the shelf? They bring huge bucks today!
I thought the distributor at that point had 2 pickups and no vacuum (that’s what the pot on that ESA is for)
Can you snap a shot of the elec ign box?

 

[DonFitzwater]

I found the valve covers on Craigslist in Anchorage....25.00!

The ignition box is in the first shot on the firewall.....rusty silver.

 

[DonFitzwater]

I fired the engine for the first time and it started immediately but needs a little carb adjustment as well as timing....I forgot my timing light at work so tomorrow evening I’ll see about firing it and breaking in the camshaft.

 

[DonFitzwater]

Here is the carter that was on it. The only wires are for the high idle/anti dieseling solenoid.

 

[DonFitzwater]

And I think I just realized the silver rusty box on the firewall is likely the voltage regulator.....can anyone confirm that?

 

[PBJ2500CTD]

And I think I just realized the silver rusty box on the firewall is likely the voltage regulator.....can anyone confirm that?

Yep. Looks like one to me...

 

[Wayne M.]

I fired the engine for the first time and it started immediately but needs a little carb adjustment as well as timing....I forgot my timing light at work so tomorrow evening I’ll see about firing it and breaking in the camshaft.

Be VERY CAREFUL breaking in that cam! In that other truck I just referenced, the guy used regular engine oil, and did just what you did, and that cam (I think it was Comp) flattened half the lobes in a week! Proof of how bad today’s oil really is!
Another guy who does a lot of race engine work stepped in and, when he got another cam, he used Lucas break in oil. And now he’s using Lucas hot rod oil in 10/40.
I wouldn’t do a thing until I got that oil, and make sure the revs are over 2000 for a half hour.

 

[TFucili]

Used to be on first start, unless something is drastically wrong, hold 2-2.5K RPM for 15 minutes to break in a cam, and no idling allowed. Aftermarket cams used to come with a little tub of break in lube.

 

[DonFitzwater]

I mixed STP in my first oil fill and primed system before starting and ensured I had oil flow through both rocker assemblies. The engine had oil pressure on the gauge before it fired and I've run it for about one minute. Sounds delightful for not being tuned in yet. Unfortunately I cant really drive it until Lokar gets me my new throttle cable assembly. I plan on running it tonight for cam break-in. I'll just set the idle way up to run where it needs to be and wait for it to get done........My normal deal is to run 100 miles close to home then do an oil change and cut the filter open...............this is all going to depend on if this turd gives me problems with ignition timing or not. I think I'm just go to order the new Mopar distributor and electronic ignition kit vs the LB "maybe" working.....or not.