Whew, what a raggedy old rig this is, anyone here have experience with these old workhorse Dodges ? .

1979 Dodge D200 long bed crew cab with all steel service bed, 8,2000 GVW so although it's technically a Medium Duty rig, it had Heavy Duty emissions check to go through .

The original Thermoquad 4 BBL carby is long gone, replaced by a Holly 4165 double bowl spread bore 4 BBL .

So far I've :

Replaced the A.I.R. pump, check valves and diverter vale .

Replaced the EGR valve , it doesn't come on @ idle , opens as the engine RPM's increase and the passages are not blocked .

Replaced the perforated distributor vacuum advance unit, cap, rotor, wires and spark plugs, gapping them to a loose .035", the FSM calls for .035" although I usually run at least .060" on HEI ignition systems .

Timing set to 6 degrees BTDC @ idle speed of 750 RPM per the FSM .

The carby was sent out for rebuilding using the nice factory Holly rebuild kit .

I've gotten the carby to idle smoothly , the engine draws 22" of vacuum at idle .

There is a slight vacuum leak in the power brake booster, until I find another one (oddly it only fits a few years of trucks) I've [pinched the booster vacuum hose closed to set the idle , it's smooth as silk now .

The air cleaner's heated air intake flap and thermostat works fine as does the dist. vacuum advance delay thermostat, I've replaced pretty much every vacuum hose under the hood .

It whistles through the idle emissions test but the cruise went from 42 PPM HC to 488 PPM @ 2,500 RPMs, I'm thinking maybe the activated charcoal cannister is not correctly connected .

This beast is too big to fit on the smog machine's rollers, so it a stationary idle and cruise test .

It used to breeze through but hasn't been tested in a couple years, old fuel drained out of the fuel tank, fresh fuel added along with new clear plastic fuel filter that's clean .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

If it was the Evap cannister, the problem should get better after a short highway cruise. Unless you’re somehow drawing raw fuel through the vapor lines. You could disconnect the cannister completely just to test.

Has it ever passed with the Holley? I’m not familiar with this carb, but it sounds like the secondary jets are too rich.

Yes, it has always passed smog with this replacement, designed for Smog application Holly 4165 carby .

I too was thinking somehow I messed up the vapor canister hoses .

When you gently rev. the engine to 2,200 RPM's it begins to load up and have a miss plus eye watering fumes out the exhaust .

Question : does the canister's position matter ? .

Factory position is on it's side, I loosened the clamp and rotated it so I could read the moulded in hose nipple markings (tank, purge, bowl) .

THANK YOU for reading and considering this .

I trained for my Ca. State smog license in 1984 and don't remember all that much, big honking American V8's were never my interest .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

There should be a check valve in the canister, so changing position may very well be the problem. Try disconnecting it and see if that helps.

This car was likely a "Lean Burn" Chrysler when it was born. The Lean Burn system was a huge advance for it's time. It used a small computer to measure temperature, manifold pressure and rpm, and adjusted fueling and advance according to a pre-programmed curve. The early versions were passive analog, they went digital around the time your truck was built. Like a lot of electronics, it was unpopular with mechanics and so most of these systems were "simplified" by going to old style carbs and distributors. To make it even tougher, Chrysler kept it's dealer network alive during their lean years by buying back spare parts inventory. So the parts you'd need to make this factory stock have long since been scrapped, and diagnostic tools and expertise lost. As a result, a generation or two of Chrysler cars are real heartbreakers.

I had a 1979 Imperial with the same engine. This was before the time we had to e-check vehicles (don't have to anymore). My ECM was mounted on the air breather, and went out 4 times in a 2 year period. I converted the engine back to a point style distro, and drove it for another year before selling it.

If it's the ECM, your luck on finding it will depend on where you look. Rock Auto has them listed, but without having any in stock. You're best luck may actually come from the gamble of Ebay.

I was concerned as soon as I saw Holley's name as the carb. I've never had luck getting an aftermarket carbed engine to pass properly...and yes, I do know how to properly set one up.

I'd reposition the canister back to it's original orientation, clear the lines, check the connections, and run some Sea Foam through it, as well as make sure you run the hell out of it before the next sniffer test. I've even heard that running some Coleman's lantern fuel in the gas tank helps, but have never personally done that. Sea Foam has always helped pass emissions.

Luckily, my trucks don't have to pass anymore...so long as I keep it under 5K miles a year of driving. All they do is check to make sure the components are still there, then do a safety check, which they always pass. Heck, I'm willing to lay a $20 bill down that my trucks would pass emissions testing if required. Neither of them have gone through it since 2011.

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1987 560SL
85,000 miles

Thanx Fellas ~

It wasn't ever a lean burn, it came with a thermo quad, was a State Highway Dept. truck when new, we've had it ever since .

This Holly, list # 4165, is specifically made for this application and used to whistle through smog tests easily .

The vapor canister doesn't have the check valve like a GM does, I'll move it back next time I get hands on it, might be to - morrow .

We had lean burn Dodge & Plymouth sedans @ L.A.P.D., they also had the stupid mini cats under the hood, right as the exhaust manifold collector, those fried everything under the hood every 15,000 miles or so .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

O.K., I found an original CARTER Thermoquad 4BBL carby and installed it, the engine seems to run fine -but- on the slightest upgrade it has zero power off idle~ I drove it to the filling station to put some fresh gasoline in it after wrestling the HUGE fuel tank off, repairing the fuel sender and re installing it and could barely get it to go up the slight hill to the man cave where I'm working .

It's been decades since I touched these (mid 1980's) and I don't remember much if anything about them, this Thermoquad carby has vacuum operated metering rods, how are they adjusted ? I see the adjustment screw but have no idea what to do, the factory shop manual and two aftermarket shop manuals simply say "DON'T TOUCH ! BAD MOJO", not really helpful .

Any ideas would be appreciated ! .

There's so much wrong / broken / worn out of this battered old rust free rig I'm beginning to write a blurb about it all as some have asked me , I don't know if I should add it here once I'm finished.....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

From what I remember, those are set at factory, tuned to a computer, if I'm not mistaken. I never messed with the screws, but took them off, dropped them off at the carb shop, picked it up and it was nearly perfect each time. If they needed adjusted, I took the car to the carb shop, and the guy would have it smooth as silk in just a few wrist twitches.

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1987 560SL
85,000 miles

Yes, that's nice, if the truck's owner had any $ that's what I'd do......

Most of the time I get jobs that no one else will touch, largely because of my 50 + years of used car / field and junkyard Mechanicing along with my Dealer time and having owned an indie shop in the 1970's ~

I often can make things work fine again when everyone else has given up .

I'm not afraid to ask for help and so often I get golden tidbits that are better than any OEM training I ever had being based on real world situations ~ someone out there has had this same problem and will know how to at lease set the base adjustment .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I wish I had more information for you.

\

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1987 560SL
85,000 miles

This may help:

http://www.carburetor-parts.com/assets/manuals/Carter_ThermoQuad_Carburetor.pdf

There were many different thermoquads, with flow rates from 500 to 1000 cfm, so the question is whether yours is a match for the engine.

I have a totally non-smog AFB that I might swap for something interesting. I'm currently looking for a good set of SU HD8 bells.

THANK YOU ! .

When I googled it I got so many links I didn't know where to begin, this looks like a good place .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

just reg it in rural az.

less headache, and prolly cheaper...

If only I could.......

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Well ;

It finally passed the smog test yesterday, it turns out the dufus Tom had rebuild the carby, didn't do it right, he left the primary bowl's float level way too high so no way it's ever lean out properly, they also failed to tighten the float valves, they were loosening up and leaking from the normal engine vibration, they installed the wrong power valve (always a problem as anyone who's ever had a 1960's Ford V8 knows) ...

Blah blah blah, yakkity woof woof, I was beginning to wonder if I'd lost my touch but it sailed through the test in the end .

Once we get the tags in hand and on the rig I'll peak & tweak the ignition timing to it has the proper giddyap of the mighty MoPar small block 360 CID V8 again .

Whew , it's road ready, still needs lots of little repairs and I'd like to get the AC going again ere long .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better