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Lean Burn vacuum advance
https://www.slantsix.org/forum/viewtopic.php?t=31695		 Page 1 of 1
Author:  cw6er [ Tue Oct 14, 2008 8:08 pm ]
Post subject:  Lean Burn vacuum advance
Where does the vacuum advance hose connect to the carb in the SCC/ELBI "Lean Burn" systems? i.e. does it take full vacuum or ported vacuum and which nipple supplies it?

It is on a Dodge D150 truck with a holly 1945

(I know, the PO did a number on it didn't he?)
Image
Author:  dusterguy225 [ Tue Oct 14, 2008 9:07 pm ]
Post subject: 
The lean burns don't have a vac advance hose, its all computer controlled.

If you want to do further upgrades, I would suggest that you might want to convert your lean burn system. Just read this and it will tell you haw to convert it, as well as give some info on it. You can probably get all the parts from various members on this forum! :D

Thats what I would try.
Author:  6shotvanner [ Tue Oct 14, 2008 9:38 pm ]
Post subject: 
Ummm,yes,no,maybe.Don't know a thing about how the pickups,cars leanburn were set up,but,on two vans I've had,yes there was a "vac advance".The vac can was mounted on the computer and plumbed here and there and everywhere :? It was a Reub Goldberg set up and found its way to the trash heap right quick on my 83.If you want to keep it I would think a ported vac source although I'm sure it went through a few other "gee whiz" items on its way from here to there.Good luck.
Author:  cw6er [ Wed Oct 15, 2008 9:54 am ]
Post subject: 
Yes, the vacuum advance dash pot or "vacuum transducer" is on the computer, and interestingly, the emissions sticker shows the vacuum line going direct from the dash pot to the carb. unfortunately, the nipples on the carb are located one right above the other, but the emissions label shows them side-by-side, so I don't know which to use.

I had thought of switching over, but that costs good money! :shock: :wink:

What, between $130 to $170? I know the computer will run the truck just fine, I had it set up with decent power and acceleration, but the tranny started shifting early and the radiator was marginal in the summer causing pinging, so I had to back off the timing to prevent it. Now I've got the transmission sorted out (shifts great, it was a gummy valve body), and just put in a new radiator now that I know the tranny is Ok. I just need to get the settings back to where they belong. As Master Card would say .... Cost: $0 - Priceless 8)

Did I mention that the truck is a "weekend beater", you know, the Home Center, the Dump, something to tinker on under the shade tree? Although, truth be told, I have been using it as a daily driver in the winter the last few years. :)
Author:  68barracuda [ Wed Oct 15, 2008 10:49 am ]
Post subject: 
If you have a vac gauge hook it up to the ports - the ported vacuum one will only show vacuum as the throttle is opened the Manifold vacuum will show high vac at idle which drops as the revs go up

Which is only half the answer - now if some one will tell you what type of signal is needed - full manifold or ported you are sorted

I would say that it would still be a ported signal..uhm well since it is computer controlled full vac could also be used

Now I am confused :? :?

DOOOOCCCCCCCC!!! or DAAAAANNNNNN!!!
Author:  Reed [ Wed Oct 15, 2008 10:51 am ]
Post subject: 
I believe the computer needs a non-ported source.
Author:  SlantSixDan [ Wed Oct 15, 2008 1:04 pm ]
Post subject: 
The service manual will have much more detailed info about the carb nipples and hose hookup than you can get from the underhood road map. The advice to ditch the lean burn is very good — such a conversion will pay for itself quickly in improved fuel economy, driveability, and performance.
Author:  cw6er [ Wed Oct 15, 2008 9:25 pm ]
Post subject: 
Well, I put a vacuum gage on the ports and they both registered the same .... full vacuum, so I guess the question is moot.
Author:  dietz_diggler [ Thu Oct 16, 2008 4:39 am ]
Post subject: 
I'll go to my parents house today and take pictures of my lean burn truck's ('84 model) system if you'd like. I have two 77 trucks and the 84. I'm pretty sure the 84's lean burn was all intact when I parked it. But I do suggest you follow the others advice and ditch the lean burn when you can though.
I'll get back w/ the pictures later today. Maybe it will help for the time being.
Dietz
Author:  Wizard [ Thu Oct 16, 2008 6:52 am ]
Post subject: 
Yes, that transductor uses manifold pressure (vacuum), finding which port with the gauge is one that works too, but service manual is so useful for diagrams.

Cheers, Wizard
Author:  cw6er [ Thu Oct 16, 2008 8:10 am ]
Post subject: 
Quote:
I'll go to my parents house today and take pictures of my lean burn truck's ('84 model) system if you'd like. I have two 77 trucks and the 84. I'm pretty sure the 84's lean burn was all intact when I parked it. But I do suggest you follow the others advice and ditch the lean burn when you can though.
I'll get back w/ the pictures later today. Maybe it will help for the time being.
Dietz
Some pictures could be very helpful, thanks

Speaking of pictures, is there a minimum number of posts before I can post pictures? I tried to post some in both the HTML code and the BBcode and neither of them would display. Any tricks to posting pics? (It's the same code I use on other boards with no problems)
Author:  dietz_diggler [ Thu Oct 16, 2008 9:22 am ]
Post subject: 
Quote:
The lean burns don't have a vac advance hose, its all computer controlled.

If you want to do further upgrades, I would suggest that you might want to convert your lean burn system. Just read this and it will tell you haw to convert it, as well as give some info on it. You can probably get all the parts from various members on this forum! :D

Thats what I would try.
I thought I had read there wasn't a vacuum advance on the lean burn... Dusterguy225 is right. My truck has an extra pigtail coming out of the back of the distributor. no vacuum advance. If yours has one I imagine its been changed. If so run your vacuum line to a port at the base of your carb. Sorry if I wasn't of any help.

But thanks to you I now know I've had an aluminum 2bbl intake and carb sitting there for the last 6 or 7 years. :o :D I noticed the flaking paint and aluminum looking spots on the intake and so I lifted the breather lid and sure enough.... I didn't know much about slants when I was driving it. It was an old farm truck I used to haul trash and go fishing with.

I parked it at my parents house, then my family got started and then one project then another, and its just sat, pretty much neglected. out of sight out of mind. anyways, thanks, and I'm sorry I couldn't be of more help to you though.
Dietz
Author:  cw6er [ Thu Oct 16, 2008 12:00 pm ]
Post subject: 
Well, the vacuum advance dash pot or "vacuum transducer" is on the computer that is bolted to the side of he air cleaner (or on the fender in some cases), not on the distributer.

A picture of the 2bbl carb (carter BBD?) might be interesting, If I get rid of the Lean Burn, isn't that something I would have to do also?
Author:  dusterguy225 [ Thu Oct 16, 2008 2:38 pm ]
Post subject: 
Quote:
A picture of the 2bbl carb (carter BBD?) might be interesting, If I get rid of the Lean Burn, isn't that something I would have to do also?
What a 2bbl? No, you can still have the 1bbl carb if you want. But, you do have to get a non lean burn carb whether its a 1 or 2 bbl (maybe a 4bbl? :shock:) thats up to you.
Author:  cw6er [ Thu Oct 16, 2008 11:05 pm ]
Post subject: 
That's what I meant, I'd have to replace the carb, and if I'm going to do that, shouldn't I be looking for an upgrade carb, or this "Super 6" set up that I keep reading about in the old posts? Or is it a waste of time unless you do head work to increase the air flow?

I'm not quite sure what the "Super 6" setup is?

And what constitutes a non-Lean Burn carb? Couldn't I just re-jet the Holly 1945 that is on there?
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