Did you check the main jet wells to make sure they are not leaking?
My 318 w/850 Thermoquad never idles well in gear, and stumbles off the line
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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re; post #25
No, not ported vacuum. I believe thats a line for the vapor canister. It doesn't pull vacuum in the usual way. It's a calibrated feed that starts flowing at a fairly wide throttle opening.IIRC. It could also be used for an EGR signal.
As to timing, if you crank in more idle-timing, as you have found out, it begins to spark-knock under load or rpm, due to being over-advanced under those conditions. The cure is to modify the mechanical advance system, to limit the power-timing, and/or to delay the vacuum advance cut-in point.
Temporarily disconnect the vacuum advance, and drive it that way for a few hours to see if its load or rpm that is causing the spark-knock.
Limiting the power-timing is accomplished by reducing the slot length in the advance plate, that sits in the bottom of the dizzy. Putting stiffer springs in there will delay the rpm when the full advance is reached. Heavy cars with tall gearing do not like too much advance at lower rpms, and generally don't want it early. Most/all sbms like more idle-timing than factory supplied, but that's not always possible if it gets into spark-knock just off idle.
Delaying the vacuum advance is accomplished through a little screw found inside the can, accessed through the vacuum nipple where the hose is attached. Almost every sbm I ever worked on benefited from quite a bit of vacuum advance (once the centrifugal was worked out), under part throttle and lite load conditions.
Once again, check the throttle shaft bushings and blade parking repeat-ability.
Why are there so many throttle return springs on there. There should be just two; a regular one, a lite back-up/safety one and no others. The back-up one is a safety, in case the main one wears out and fails.There should be another lite one returning the KD mechanism. It goes backwards towards the firewall.
If your fuel fill-ups are far in-between, water can accumulate in the system. Eventually that water finds its way into the carb, from where it, passes through the jets. This can/does cause driveability issues, especialy as it likes to settle in the lowest place in the bowl, you guessed it, the mainwells. It seems to be much worse with alcoholized fuels which are hydroscopic,that is, they attract moisture right out of the atmosphere. Perhaps a stabilizer can help you, or, a gas-line antifreeze. These agents work by binding the moisture to the fuel molecules, preventing them from accumulating in puddles. They then go through the jets in the normal way and are hardly noticeable under anything except the occasional hiccup at idle.
If your EGR valve is still functional, it too could be the source of your woes. Temporarily defeat it,when the engine is idling well. And roadtest for a few days/ miles.
No, not ported vacuum. I believe thats a line for the vapor canister. It doesn't pull vacuum in the usual way. It's a calibrated feed that starts flowing at a fairly wide throttle opening.IIRC. It could also be used for an EGR signal.
As to timing, if you crank in more idle-timing, as you have found out, it begins to spark-knock under load or rpm, due to being over-advanced under those conditions. The cure is to modify the mechanical advance system, to limit the power-timing, and/or to delay the vacuum advance cut-in point.
Temporarily disconnect the vacuum advance, and drive it that way for a few hours to see if its load or rpm that is causing the spark-knock.
Limiting the power-timing is accomplished by reducing the slot length in the advance plate, that sits in the bottom of the dizzy. Putting stiffer springs in there will delay the rpm when the full advance is reached. Heavy cars with tall gearing do not like too much advance at lower rpms, and generally don't want it early. Most/all sbms like more idle-timing than factory supplied, but that's not always possible if it gets into spark-knock just off idle.
Delaying the vacuum advance is accomplished through a little screw found inside the can, accessed through the vacuum nipple where the hose is attached. Almost every sbm I ever worked on benefited from quite a bit of vacuum advance (once the centrifugal was worked out), under part throttle and lite load conditions.
Once again, check the throttle shaft bushings and blade parking repeat-ability.
Why are there so many throttle return springs on there. There should be just two; a regular one, a lite back-up/safety one and no others. The back-up one is a safety, in case the main one wears out and fails.There should be another lite one returning the KD mechanism. It goes backwards towards the firewall.
If your fuel fill-ups are far in-between, water can accumulate in the system. Eventually that water finds its way into the carb, from where it, passes through the jets. This can/does cause driveability issues, especialy as it likes to settle in the lowest place in the bowl, you guessed it, the mainwells. It seems to be much worse with alcoholized fuels which are hydroscopic,that is, they attract moisture right out of the atmosphere. Perhaps a stabilizer can help you, or, a gas-line antifreeze. These agents work by binding the moisture to the fuel molecules, preventing them from accumulating in puddles. They then go through the jets in the normal way and are hardly noticeable under anything except the occasional hiccup at idle.
If your EGR valve is still functional, it too could be the source of your woes. Temporarily defeat it,when the engine is idling well. And roadtest for a few days/ miles.
daredevil
Well-Known Member
A lot of good info here but I would still like to see a couple plugs. I have always looked at them as a carb tuning tool.
Yes, the vacuum advance can should have a Allen key Turnable screw in it to limit total advance. IIRC, clockwise limits the amount of advance. If you have the cap off and you turn the screw, you can see movement inside the distributor.
A/J. The yellow capped port in the bowl is for the EGR valve. The EGR stops working at aggressive throttle applications. Put a vacuum gauge on the valve itself and start pump the gauge to pull vacuum. When it starts to move, record the amount of vacuum and restart pulling vacuum until it fully opens up, record the number.
A/J. The yellow capped port in the bowl is for the EGR valve. The EGR stops working at aggressive throttle applications. Put a vacuum gauge on the valve itself and start pump the gauge to pull vacuum. When it starts to move, record the amount of vacuum and restart pulling vacuum until it fully opens up, record the number.
8v-of-fury
Active Member
I checked them 1.5 years and 4500kms ago, at the time they were still intact and all was well. I do suppose the introduction to fuels again could have done some funk on them..
re; post #25
No, not ported vacuum. I believe thats a line for the vapor canister. It doesn't pull vacuum in the usual way. It's a calibrated feed that starts flowing at a fairly wide throttle opening.IIRC. It could also be used for an EGR signal.
Ah, that would make some sense right there!Yah I guess being mid venturi would suggest it is a wider throttle opening at which it would see some vacuum.
As to timing, if you crank in more idle-timing, as you have found out, it begins to spark-knock under load or rpm, due to being over-advanced under those conditions. The cure is to modify the mechanical advance system, to limit the power-timing, and/or to delay the vacuum advance cut-in point.
Temporarily disconnect the vacuum advance, and drive it that way for a few hours to see if its load or rpm that is causing the spark-knock.
I have the vacuum advance disconnected permanently right now, as there is no safe way to be able to drive it. If I wanted to have the vacuum hooked up and not knock base timing would need to be in the ATDC marks. So I think you have slightly misunderstood what I am saying, unless I misunderstand you right now about this ? LOL. With the vacuum advance disconnected I still get the SLIGHTEST knock but only under severe acceleration and WOT.With the vacuum advance hooked up, it does seem to be load that does it and not RPM. You could be just starting to move in 1st gear and give it a bit more throttle and the diesel knock comes on strong under the hood.
Limiting the power-timing is accomplished by reducing the slot length in the advance plate, that sits in the bottom of the dizzy. Putting stiffer springs in there will delay the rpm when the full advance is reached. Heavy cars with tall gearing do not like too much advance at lower rpms, and generally don't want it early. Most/all sbms like more idle-timing than factory supplied, but that's not always possible if it gets into spark-knock just off idle.
I was thinking about getting some of these dizzy tuning rings to help with the mechanical advance matter actually.
Why are there so many throttle return springs on there. There should be just two; a regular one, a lite back-up/safety one and no others. The back-up one is a safety, in case the main one wears out and fails.There should be another lite one returning the KD mechanism. It goes backwards towards the firewall.
There is one extra throttle spring on there to provide a more firm feeling pedal, and to provide a sure return to idle when I let off the pedal. Beginning of this week had the throttle sticking on just off idle, which I think was just weak old springs not bringing it back securely every time. So you say there is supposed to be a spring on the trans kick down arm as well? Now there is some other lines of questioning I have actually, because this is a 2bbl kick down arm on a 4bbl carb.. it doesn't necessarily work properly. It is supposed to be held with spring pressure towards the firewall?
If your fuel fill-ups are far in-between, water can accumulate in the system. Eventually that water finds its way into the carb, from where it, passes through the jets. This can/does cause driveability issues, especialy as it likes to settle in the lowest place in the bowl, you guessed it, the mainwells. It seems to be much worse with alcoholized fuels which are hydroscopic,that is, they attract moisture right out of the atmosphere. Perhaps a stabilizer can help you, or, a gas-line antifreeze. These agents work by binding the moisture to the fuel molecules, preventing them from accumulating in puddles. They then go through the jets in the normal way and are hardly noticeable under anything except the occasional hiccup at idle. If your EGR valve is still functional, it too could be the source of your woes. Temporarily defeat it,when the engine is idling well. And roadtest for a few days/ miles.
I run through roughly 1.5 tanks per month, but the car does sit idle for 3 weeks while I am gone.. There is no EGR anymore, I bought a used EDDIE intake that was EGR-less.
I will get you a picture of a few plugs ;) lol
340fourspeedDuster
Well-Known Member
From what I am seeing, this carb needs another rebuild. There is buildup of dirt/etc in the wells, and the float bowls. It looks as if the fuel level slowly evaporated leaving the discolored section in the wells where the floats reside. The seals (#49) look hardened and should be replaced.
Not knowing the mileage, past 100km, I am wondering about stretch of the timing chain. These motors only used a "silent" chain, as apposed to a double roller from the factory.
Was the timing chain replaced in any of the past records?
Your GM bought the vehicle new in 1988. Zero miles. How long until she put 100km on the car? Provided she did not loan the car to someone that put "tons" of kilos on the car, or the opposite where it sat for years parked, you should be able to guess-to-mate mileage much closer than 200km or 300km. Example: 100km driven in 10 years (120 months) 100,000/120 =833km/month. Extrapolate this out until you reach 2015. Keep in mind of other trips, loaning the car, or it being parked for an extended time.
Give us a pic of some (or all) of the spark plugs.
Remember, the 318 engines are ONLY good for 500,000km LOL
I am concerned about moisture in the gas also. Fresh gas and a quality pour-in product may help here.
Not knowing the mileage, past 100km, I am wondering about stretch of the timing chain. These motors only used a "silent" chain, as apposed to a double roller from the factory.
Was the timing chain replaced in any of the past records?
Your GM bought the vehicle new in 1988. Zero miles. How long until she put 100km on the car? Provided she did not loan the car to someone that put "tons" of kilos on the car, or the opposite where it sat for years parked, you should be able to guess-to-mate mileage much closer than 200km or 300km. Example: 100km driven in 10 years (120 months) 100,000/120 =833km/month. Extrapolate this out until you reach 2015. Keep in mind of other trips, loaning the car, or it being parked for an extended time.
Give us a pic of some (or all) of the spark plugs.
Remember, the 318 engines are ONLY good for 500,000km LOL
I am concerned about moisture in the gas also. Fresh gas and a quality pour-in product may help here.
8v-of-fury
Active Member
Those pictures of the bowls and what not are pre rebuild 1.5 years ago. I got that carb from a shipping container full of carbs and intakes. So it likely was plucked full of fuel yes and left to sit.
I would say no the timing chain has never been replaced, however now that I think of it.. the timing cover looks new, as in not covered in shmutz like the rest of the engine. So it is very possible.. I'll have to ask her. She's 82 and her memory is sharp.. but she never was a car person so that knowledge likely just isn't there.
I would say no the timing chain has never been replaced, however now that I think of it.. the timing cover looks new, as in not covered in shmutz like the rest of the engine. So it is very possible.. I'll have to ask her. She's 82 and her memory is sharp.. but she never was a car person so that knowledge likely just isn't there.
The beauty of timing chains are there inexpensive price tags.
AJ/FormS
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1)No to your KD spring question.If you have the 2bbl KD link on the TQ, it will be too short, and you risk burning out the transmission. The carb linkage must push the KD link, waaay back as far as it can go. This is best figured by disconnecting the link from the throttle lever, then pushing it as far back as it will go, holding it there, and then with the Carb at WOT, the KD link should just barely be able to be reinstalled. Then a spring should be installed onto that same link rod,and connected to the throttle lever, in such a way as to return it to its parked position with the throttle lever also parked at idle. This spring ,however, must have little to no tendency to open the throttle lever, when the other springs are removed. A tiny bit could be normal,as the linkage is somewhat weighty. This behavior is not possible with the too-short 2bbl linkrod. So fix that first.
2) timing chain stretch is easy to estimate.Just rock the crank back and forth against a parked-by-spring-pressure, cam. There is a spec for that,but I forget it. I'd guess the crappy silent chains start out with a degree or so when new and just run in. So I'd guess they're good for at least 3 to 5 degrees, before you might notice a performance change.I've seen them run so loose they were hitting the case.
2) timing chain stretch is easy to estimate.Just rock the crank back and forth against a parked-by-spring-pressure, cam. There is a spec for that,but I forget it. I'd guess the crappy silent chains start out with a degree or so when new and just run in. So I'd guess they're good for at least 3 to 5 degrees, before you might notice a performance change.I've seen them run so loose they were hitting the case.
8v-of-fury
Active Member
It is not the price of the timing chain that is the issue ;) it is the price tags of all other things you remove in the process that should also be replaced! LOL Also of course, the time to complete said job.
It has a rock steady timing mark, so I would assume it hasn't much if any play.. Could I take the cap off the dizzy and see if there is a delayed turn from turning the crank pulley CW and CCW?
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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^^ yes, on the rocking.
Now lets get back to the KD linkrod.
The rod when it is on the throttle lever, must be able to move the same far back, as what it can when it is off the lever. If the tranny cannot get full throttle pressure this way, it will self-destruct when asked to work hard, as in WOT full load. So you better take it easy until this gets sorted out.
I would make this priority one, unless you enjoy overhauling trannies.
Now lets get back to the KD linkrod.
The rod when it is on the throttle lever, must be able to move the same far back, as what it can when it is off the lever. If the tranny cannot get full throttle pressure this way, it will self-destruct when asked to work hard, as in WOT full load. So you better take it easy until this gets sorted out.
I would make this priority one, unless you enjoy overhauling trannies.
8v-of-fury
Active Member
I appreciate your knowledge and willingness to help me AJ !
This is a (more-or-less) bone stock 88 5th avenue! LOL How much full load WOT do you think it sees? ;) It's either in D and has real slow gettup-and-go (due to shift points being sooooo goddamn low) or I am shifting 1-2-3 on the column. Which produces WAY better take-off and maneuverability.
The rod may not reach WOT position, but the throttle is never near WOT anyway.
However, I do recall the car having a part throttle kick down that it does not have anymore. Would be great if it worked.
!This is a (more-or-less) bone stock 88 5th avenue! LOL How much full load WOT do you think it sees? ;) It's either in D and has real slow gettup-and-go (due to shift points being sooooo goddamn low) or I am shifting 1-2-3 on the column. Which produces WAY better take-off and maneuverability.
The rod may not reach WOT position, but the throttle is never near WOT anyway.
However, I do recall the car having a part throttle kick down that it does not have anymore. Would be great if it worked.
AJ/FormS
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The very low shift points prove the linkrod is too short. Keep driving it like that and you will be looking at an overhaul. With a heavy car like that it won't take long.i
8v-of-fury
Active Member
HUH interesting. Never knew that it would work that way.
Hear me out though, I am not saying the rod doesn't need to be righted, so dont think that.
The rod, from idle, moves with the throttle the whole way through its movement as it would have in 2bbl form. The KD moves directly with the throttle as it would have from factory.
The only difference from 2bbl to 4bbl I can see is that I may be pushing the throttle more to get the same performance from the engine due to the larger primary throttle size.
Hear me out though, I am not saying the rod doesn't need to be righted, so dont think that.
The rod, from idle, moves with the throttle the whole way through its movement as it would have in 2bbl form. The KD moves directly with the throttle as it would have from factory.
The only difference from 2bbl to 4bbl I can see is that I may be pushing the throttle more to get the same performance from the engine due to the larger primary throttle size.
8v-of-fury
Active Member
It is shifted in to third by about 40km//h, and then lockup at 60km/h.
8v-of-fury
Active Member
From what I have just read a 25kmh 1-2 shift and 35kmh 2-3 shift is entirely normal under light acceleration, however this is entirely too low and drops the engine to roughly 1500rpm where it makes dick all for power.
So basically I want that rod to be as long as I can more-or-less make it... ? Cause I have no problem with the engine shifting at 3000 or w.e when it has actually had a chance to make some power. Plus, then the part throttle downshift will come in sooner.. so that is a major plus too.
random interwebz guy said:
So basically I want that rod to be as long as I can more-or-less make it... ? Cause I have no problem with the engine shifting at 3000 or w.e when it has actually had a chance to make some power. Plus, then the part throttle downshift will come in sooner.. so that is a major plus too.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I guess I'm not making it clear. I'll try one more time.
Get a helper to stomp the gas pedal down. Make sure the throttle is ALL the way open. Now see if you can push the installed KD link back any further. If yes, that's a problem.There is no other solution but to lengthen the rod. If no, check for an obstruction to the rearward motion.
The 4bbl throttle lever is between 1.25 and 2 inches closer to the rad than the 2bbl lever.I can't recall the exact distance. This has to be corrected. Both in the linkrod and in the cable.
You cannot properly use a 2bbl cable, on a 4bbl carb.The exposed inner cable is too short.Unless you modify your pedal-stop.
It is difficult to use a 2bbl cable anchor on a 4bbl application. Each is it's own set-up. That is; the carb, the cable and the link-rod are a set.
If you clamped the cable on the black outer sheath, shame on you. You are looking at a possible run-away engine as the outer sheath puts a clamp on the inner cable, and it's possible for the throttle not to return. The correct place to clamp the outer sheath is on the approximate 2 inch steel anchor sleeve. Wrong parts won't allow that.
Get a helper to stomp the gas pedal down. Make sure the throttle is ALL the way open. Now see if you can push the installed KD link back any further. If yes, that's a problem.There is no other solution but to lengthen the rod. If no, check for an obstruction to the rearward motion.
The 4bbl throttle lever is between 1.25 and 2 inches closer to the rad than the 2bbl lever.I can't recall the exact distance. This has to be corrected. Both in the linkrod and in the cable.
You cannot properly use a 2bbl cable, on a 4bbl carb.The exposed inner cable is too short.Unless you modify your pedal-stop.
It is difficult to use a 2bbl cable anchor on a 4bbl application. Each is it's own set-up. That is; the carb, the cable and the link-rod are a set.
If you clamped the cable on the black outer sheath, shame on you. You are looking at a possible run-away engine as the outer sheath puts a clamp on the inner cable, and it's possible for the throttle not to return. The correct place to clamp the outer sheath is on the approximate 2 inch steel anchor sleeve. Wrong parts won't allow that.
8v-of-fury
Active Member
I do not understand why you are getting offended or feel like I am not comprehending you, I am not saying "You're wrong" "I will make it work my own way.. blah blah". I am simply trying to understand the system, if I went through life just taking peoples word on things and never inquiring deeper as to how it works or what it does I'd be dumber than a bag'o'hammers.
Please do not take my inquisitiveness for lack of comprehension on the matter. I am truly just trying to understand how it works ENTIRELY.
Actually, If you move the 2bbl throttle bracket back to the next set of intake manifold bolts everything lines up just as it should. Cable attached you can bring the idle screw right out of the carb and have the throttle blade set itself completely. It also reaches WOT or damn near close to it, as the secondaries have no issue coming open. Even if it does not reach true WOT, for the time being, I am fine with that.
I do understand now why the car has such a CLUNK going in to drive or reverse though! The clutches are already ramped up and applying pressure, or whatever they do.
Please do not take my inquisitiveness for lack of comprehension on the matter. I am truly just trying to understand how it works ENTIRELY.
Actually, If you move the 2bbl throttle bracket back to the next set of intake manifold bolts everything lines up just as it should. Cable attached you can bring the idle screw right out of the carb and have the throttle blade set itself completely. It also reaches WOT or damn near close to it, as the secondaries have no issue coming open. Even if it does not reach true WOT, for the time being, I am fine with that.
I do understand now why the car has such a CLUNK going in to drive or reverse though! The clutches are already ramped up and applying pressure, or whatever they do.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I'm not offended in the least.
And if you move the bracket up to the next holes,you completely destroy the KD geometry.
And if you move the bracket up to the next holes,you completely destroy the KD geometry.
8v-of-fury
Active Member
It would appear that way, hmm. Well I had to mount it on the next ones back to clear the 4bbl Thermoquad, as its a wide bastard.
Hmm, ****. This is a game changer. I am unsure if it really changes the geometry, it still just pushes the rod down to the tranny, if anything moving it back may have shortened the rod that goes down to the trans by putting it at a bit of an angle.
In 2 weeks when I am with the car again (currently 4500kms away) I will check the setup as you have posted several times ;) and make sure I can get it all proper.
Upon some research, it would appear moving the bracket back would have very minimal affect on the geometry of the KD assembly.
Hmm, ****. This is a game changer. I am unsure if it really changes the geometry, it still just pushes the rod down to the tranny, if anything moving it back may have shortened the rod that goes down to the trans by putting it at a bit of an angle.
In 2 weeks when I am with the car again (currently 4500kms away) I will check the setup as you have posted several times ;) and make sure I can get it all proper.
Upon some research, it would appear moving the bracket back would have very minimal affect on the geometry of the KD assembly.
8v-of-fury
Active Member
So today I took apart and cleaned my Thermoquad, the idle passageway on the passenger side was pretty gummed up so i soaked the carb over night in pieces in a tub.
However, after getting it back on tonight and without resetting the idle screws (it was dark and I needed to drive it immediatey home.. lol so a base setting of 1.5 turns out each) I had a beautiful cold start, a beautiful cold and hot idle and a stellar hot start!
HOWEVER, now I have a horrible stumble in the primaries? I didn't touch the rods, adjustment or change anything to do with the primaries. So I am unsure on that one.
However, after getting it back on tonight and without resetting the idle screws (it was dark and I needed to drive it immediatey home.. lol so a base setting of 1.5 turns out each) I had a beautiful cold start, a beautiful cold and hot idle and a stellar hot start!
HOWEVER, now I have a horrible stumble in the primaries? I didn't touch the rods, adjustment or change anything to do with the primaries. So I am unsure on that one.
darkron9
New Member
I'm new here, just joined the group and noticed your off idle stumble problem with your 318 with the Thermoquad. Pardon me if you've already tried these things.
These are things I have done to fix the problem on mine. (I actually own a 1978 Dodge Custom 100 PU with a 318 and Thermoquad from the factory.)
1. See if you get a pair of #1966 metering rods. I got mine from http://quadrajetparts.com/thermo-quad-metering-rods-067045-1966-p-912.html Yes I know the website is mostly for QJets, but they also have a good selection of TQ parts as well.
2. I also had to enlarge the accelerator pump squirters on my TQ to around .032 from the stock size.
3. And, I was able to find a step up spring that both long and "strong". This is actually documented in the Edelbrock Carter pdf file for AFB and AVS carbs to help out the off idle stumble on those models of carbs and the same adjustment works on the TQ. Edelbrock suggests that on the AFB/AVS carbs that you replace the step up spring with the strongest one they manufacture, silver. If this works, then go down a step to a pink spring and see if this still works. As it turns out, the TQ is just an evolution of the AVS carb and tunes in a simular way. Those carb users have the luxury of a manufacturer that is still manufacturing tune up parts for their carbs.
Now the bad part, I can't seem to find any source of step up springs for the TQ today. I am trying out springs that I find in my local hardware store but this is purely trial and error. I was fortunate in buying several "junker" TQs during the late 90's for a song. These days even the junkers go for a what I consider a pretty high price. The best spring I have found so far for the 1 1/2" primary TQ on a 318 came from a 1973 TQ. This spring may or may not have been replace at some point in time as this was one of the junker carbs I'd bought nearly 20 years ago.
Lastly, you can also try this tip I'd found on a post years ago. There are two holes in the choke tower that eventually lead down to the air fuel mixture screws. The early carbs didn't have these holes. Some guys have said that plugging the holes helps. You can use tape to cover these holes temporarily to see plugging the holes does help in your situation.
Be forewarned that plugging the holes may cause your car to not be able to pass smog testing in your area. This is why I suggest using tape as a temporary measure. For a more permanent change, use JB Weld to plug the holes.
Recently, I've tried backing out of the changes I've made on my TQ one by one only to find the off idle stumble come back with a vengeance, so if your setup is similar to mine, you will have to do all the changes.
Why so many changes? For me where I live, its due to California's use of Ethenol in the fuel we use out here in high smog areas.
Please forgive me if my points have already been covered. Also to the admins, I hope it is ok to post a URL to a website that offers parts for the TQ.
These are things I have done to fix the problem on mine. (I actually own a 1978 Dodge Custom 100 PU with a 318 and Thermoquad from the factory.)
1. See if you get a pair of #1966 metering rods. I got mine from http://quadrajetparts.com/thermo-quad-metering-rods-067045-1966-p-912.html Yes I know the website is mostly for QJets, but they also have a good selection of TQ parts as well.
2. I also had to enlarge the accelerator pump squirters on my TQ to around .032 from the stock size.
3. And, I was able to find a step up spring that both long and "strong". This is actually documented in the Edelbrock Carter pdf file for AFB and AVS carbs to help out the off idle stumble on those models of carbs and the same adjustment works on the TQ. Edelbrock suggests that on the AFB/AVS carbs that you replace the step up spring with the strongest one they manufacture, silver. If this works, then go down a step to a pink spring and see if this still works. As it turns out, the TQ is just an evolution of the AVS carb and tunes in a simular way. Those carb users have the luxury of a manufacturer that is still manufacturing tune up parts for their carbs.
Now the bad part, I can't seem to find any source of step up springs for the TQ today. I am trying out springs that I find in my local hardware store but this is purely trial and error. I was fortunate in buying several "junker" TQs during the late 90's for a song. These days even the junkers go for a what I consider a pretty high price. The best spring I have found so far for the 1 1/2" primary TQ on a 318 came from a 1973 TQ. This spring may or may not have been replace at some point in time as this was one of the junker carbs I'd bought nearly 20 years ago.
Lastly, you can also try this tip I'd found on a post years ago. There are two holes in the choke tower that eventually lead down to the air fuel mixture screws. The early carbs didn't have these holes. Some guys have said that plugging the holes helps. You can use tape to cover these holes temporarily to see plugging the holes does help in your situation.
Be forewarned that plugging the holes may cause your car to not be able to pass smog testing in your area. This is why I suggest using tape as a temporary measure. For a more permanent change, use JB Weld to plug the holes.
Recently, I've tried backing out of the changes I've made on my TQ one by one only to find the off idle stumble come back with a vengeance, so if your setup is similar to mine, you will have to do all the changes.
Why so many changes? For me where I live, its due to California's use of Ethenol in the fuel we use out here in high smog areas.
Please forgive me if my points have already been covered. Also to the admins, I hope it is ok to post a URL to a website that offers parts for the TQ.
darkron9
New Member
One more thing I forgot to say in my reply. Do yourself a big favor and replace your nitrophyl floats with brass floats. None of the adjustments will work properly until you do this. The brass floats are still available online.
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