I'm to old of a dog to learn that trick.....whew
79 propane carb adjustments
Thread Starter
Heel & Toe
Joined: May 2012
Posts: 22
Likes: 0
From: Los Angeles California
79 propane carb adjustments
I'm just getting into the new toy (79 L48), and preparing for smog in CA. One of the adjustments I may need to make is the idle mixture. The manuals, I have, reference a Propane Enrichment Idle Mixture Adjustment which requires a "special" propane tool. What have any of you wizards used for this function?
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
No propane expert here, but do know it's a way to pass the sniffer without cat converters. You may want to check with the local air resources board before spending a lot of tuning time, as many CA areas have visual inspections. This means 100% as it came from the factory, including single cat converter and air pump. Sure others will chime in.
Thread Starter
Heel & Toe
Joined: May 2012
Posts: 22
Likes: 0
From: Los Angeles California
Yes gentlemen, the manual indicates for 78-79 the only method of adjusting the idle mixture involves the use of a propane tool (GM J-26911). This procedure is not usually needed but the previous owner had "someone" work on the vehicle and I may need to make an adjustment. In speaking with an older smog tech, I have learned that this is in fact the case. Due to some fuel substitution process of which I am only mildly familiar, the adjustment process involves propane. I am hoping some adventurous member has already done this and can provide some guidance.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
There are literally a gazillion '79 owners on this forum. They're always here asking questions. I'm sure at least a hundred will come to your aid with a suitable answer. Just wait.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Yes gentlemen, the manual indicates for 78-79 the only method of adjusting the idle mixture involves the use of a propane tool (GM J-26911). This procedure is not usually needed but the previous owner had "someone" work on the vehicle and I may need to make an adjustment. In speaking with an older smog tech, I have learned that this is in fact the case. Due to some fuel substitution process of which I am only mildly familiar, the adjustment process involves propane. I am hoping some adventurous member has already done this and can provide some guidance.
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Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Propane tool? How 'bout natural gas?
Natural gas burns clean too and would help u pass smog but is difficult to get into the carb. You would need a collector hood inside the passenger compartment and a little 12V DC compressor pump running off the cigarette lighter to force it into the carb. This system works most effective after a meal at Taco Bell. I heard the Chinese have adapted this to livestock pens to run a stove, furnace or whatever - corvette could be next.
cardo0
cardo0
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
I had a 1985 Dodge Caravan that had a messed up carb the day I took delivery. The dealership tweaked the carb so I could at least drive it and then they finally found the real problem. When they adjusted the carb back to spec I saw a grille-sized bottle of propane on the shop floor and a hose running into the engine bay.
I think there may be a special port on your carb (if it's stock) for a propane tank hookup. I have no idea what the propane is used for while tuning but apparently it is needed to get the stock carb adjusted properly. Good luck finding the fitting.
Rick B.
I think there may be a special port on your carb (if it's stock) for a propane tank hookup. I have no idea what the propane is used for while tuning but apparently it is needed to get the stock carb adjusted properly. Good luck finding the fitting.
Rick B.
Thread Starter
Heel & Toe
Joined: May 2012
Posts: 22
Likes: 0
From: Los Angeles California
Yeah, I read the tech directions and it is a bit of a process. Anyway the Adjusting screws are visible (nearly) from the front of the carb using a flashlight and a small inspection mirror. They are small hex head screws in recesses at the front. The special PEIM procedure is listed as strictly for the 78-79 carb instead of the standard seat and back-off process indicated for the 72-77 model. Anyone got anything inovative?
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
It's called propane enrichment.
http://www.thetoolwarehouse.net/p-4452-otc-7148.aspx
http://ezinearticles.com/?Procedures...hod&id=1395808
http://www.thetoolwarehouse.net/p-4452-otc-7148.aspx
http://ezinearticles.com/?Procedures...hod&id=1395808
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Yeah, I read the tech directions and it is a bit of a process. Anyway the Adjusting screws are visible (nearly) from the front of the carb using a flashlight and a small inspection mirror. They are small hex head screws in recesses at the front. The special PEIM procedure is listed as strictly for the 78-79 carb instead of the standard seat and back-off process indicated for the 72-77 model. Anyone got anything inovative?
Thread Starter
Heel & Toe
Joined: May 2012
Posts: 22
Likes: 0
From: Los Angeles California
Thanks '75, that's what I found too. Roger, the missing caps are the reason I think someone messed with the mixture in the past. I am working through the system and am hoping to have a less expensive tool option if I end up needing to adjust the idle mixture. The E-_ _ _ link above is a vintage tool @+/- $75 which still seems high for something I hope I'll never need again. We all know I most likely will do this again at some point, so I might just bite the bullet at this point.
