Thermoquad questions

[Challenger RTA]

I
The problem of weeping is still there. Had it apart a few times. Removed top with fuel in it. The fuel level was half way up. I would think with the floats in the bowl would raise the fuel level a bit. Checked the float level adjustment again 29/32nds . Been reading other forums on the thermoquad. Enlarging the transition slot is that a doable thing? The other is to drill holes in the primary plates. some start at 1/16" and maybe end up at 3/32nd".
II
As the pictures go The throttle plate are mechanically closed. The throttle plate being held up to the light at different angles. The light can be seen in different areas. I would have to say that there needs to be some opening in order for the engine to run. I did flip the plate around and no difference or wouldn't fit. The other thing that came to mind, is to trim off material for more air flow instead of drilling hole. I would a have guess someone has tried that and it would be to difficult to know how much to remove.
III
The one thing I didn't do is check the fuel pressure. It's not that hard. Just want a third eye to watch if something is amuck. While I focus on what I'm doing. Having things apart a few time one can miss something.
IV
The last picture is one with the 1 1/2" primaries 9103s. Wondering if there is no need to drill the primary plates because of the larger bore. Will it give the engine what it needs? The problem with the 2nd one 9103s. To rebuild it I think I have all the parts but the air door spring. I'm thinking I can go a head and rebuild it. I just want to see if there is the same problem weeping. Don't need the secondary to open. If need be I'll fasten them shut. just checking at idle. If it's good I'll order pasts that I need. If not I'll ordering parts anyhow.
V
@Vaanth Or other. Any input would be apricated Thanks

 

[Ricks72Chlgr440]

The pictures show the transfer slot is too far exposed, which will cause the fuel to drip from the boosters. When the throttle is completely closed, the transfer slot exposure should be close to resembling a square. I have put TQ's on a number of warmed over engines and never needed to drill the butterflies to provide more airflow. What is your initial timing set to? Did you recurve the distributor to provide more timing at a lower speed? That may be what the engine is wanting and why the throttle is opened so much to compensate for lack of timing. Just a thought...

 

[Challenger RTA]

This carb was on a 383 challenger I had and it worked okish. Just drove it.
But it was a rebuild from an auto parts store back in the late 80's. Transfer slot exposure. So that means the linkage was not set up. right from the get go. Thinking it was correct./\ What picture are you looking at. Some are from the top side.

I did recurve the distributor.

 

[Ricks72Chlgr440]

This carb was on a 383 challenger I had and it worked okish. Just drove it. But it was a rebuild from an auto parts store back in the late 80,s. Transfer slot exposure. So that means the linkage was not set up. right from the get go. Thinking it was correct./\ What picture are you looking at. Some are from the top side.

I did recurve the distributor.

This picture, for example. The transfer slot should be close to a square. You may need to reset your mixture screws once the throttles are closed to make the square. Certainly possible that the linkage is a bit off, would not be the first time I've seen that. Having the idle too high can mask the timing being inadequate. Reason I go here is because fuel dribble thru the boosters at idle is a dead giveaway that there is too much air flowing across the boosters... which should not happen at idle. Are you running vacuum advance? If so, ported or manifold?

 

[Challenger RTA]

Ported vacuum. thinking it is more of a street machine use. I didn't notice it before but I wasn't having any trouble. Until The distributor need work and not running right. After it sat for the winter.

 

[Ricks72Chlgr440]

Ported vacuum. thinking it is more of a street machine use. I didn't notice it before but I wasn't having any trouble. Until The distributor need work and not running right. After it sat for the winter.

Running manifold vacuum will increase the idle RPMs so you can reduce the idle screw to reduce the transfer slots some. Give that a try.

 

[Vaanth]

I
The problem of weeping is still there. Had it apart a few times. Removed top with fuel in it. The fuel level was half way up. I would think with the floats in the bowl would raise the fuel level a bit. Checked the float level adjustment again 29/32nds . Been reading other forums on the thermoquad. Enlarging the transition slot is that a doable thing? The other is to drill holes in the primary plates. some start at 1/16" and maybe end up at 3/32nd".

Enlarging the transfer slots should not be done, and likely would worsen the situation and cause erratic operation. Some notes on drilling follow.

II
As the pictures go The throttle plate are mechanically closed. The throttle plate being held up to the light at different angles. The light can be seen in different areas. I would have to say that there needs to be some opening in order for the engine to run. I did flip the plate around and no difference or wouldn't fit. The other thing that came to mind, is to trim off material for more air flow instead of drilling hole. I would a have guess someone has tried that and it would be to difficult to know how much to remove.

Ensuring that the throttle plates completely shut with the throttle closed ensure proper alignment. At curb idle, they are not fully closed, so a perfect seal closed is not required or even possible. Don't trim the plates. Doing so will just complicate adjustments and tuning.

III
The one thing I didn't do is check the fuel pressure. It's not that hard. Just want a third eye to watch if something is amuck. While I focus on what I'm doing. Having things apart a few time one can miss something.

Verifying that fuel pressure is not too high is good. If your pump is stock, or stock pressure, and healthy, fuel pressure should not be an issue.

IV
The last picture is one with the 1 1/2" primaries 9103s. Wondering if there is no need to drill the primary plates because of the larger bore. Will it give the engine what it needs? The problem with the 2nd one 9103s. To rebuild it I think I have all the parts but the air door spring. I'm thinking I can go a head and rebuild it. I just want to see if there is the same problem weeping. Don't need the secondary to open. If need be I'll fasten them shut. just checking at idle. If it's good I'll order pasts that I need. If not I'll ordering parts anyhow.

The 9103's larger primaries is not necessarily a fix for what is ailing your 6319. It's not a case of the engine needing more, it's what is causing nozzle drip, that may be causing your idle issue, or contributing to it with something else amiss.

The likelihood that I mentioned earlier, and as noted by Rick, is that the throttle plates are too far open at idle, exposing too much of the transition slots, which is pulling in the low speed circuit, and causing the nozzle drip.

Building the 9103, and replacing the 6319 to rule out the carburetor altogether is not a bad approach. If you then have to set the idle high enough to also cause it to have nozzle drip, you'll need to determine why and/or compensate.

Drilling the throttle plates can allow you to lower the plates with the idle screw which then does not overexpose the transition slots, as well as the ported vacuum slot which can cause erratic operation at idle. By the way, the 9103 does not have the ported vacuum advance slot unless you add it. However, drilling is usually not necessary, and can still cause the venturi flow to lead to nozzle drip, albeit not as much so. Drilling the secondary plates can get around it.

Your camshaft with the 1.6 rockers is relatively healthy compared to stock. More initial timing advance may be required to kick the idle up and allow the idle screw to be backed off, lowering the throttle plates. Using full manifold vacuum for the distributor vacuum advance, as Rick notes, can be used similarly to increasing initial advance. I might use that as a tool, but I prefer ported vacuum advance for regular operation.

To see how more air introduced can help for higher idle with the throttle plates lowered, you can introduce a vacuum leak by leaving the rear port for the air cleaner open and see if you can control the idle and stop the nozzle drip. This too is just a tool to verify that more air with less plate opening is needed.

NOTE: I noticed earlier that the 6319 seems to have been though a mass rebuilder operation, at least the throttle body. The Teflon coating is gone from the throttle shafts. Although this is not always an indicator of trouble, it can be. When the parts are blasted or tumbled, they can be troublesome to work with if not outright bad. If it was running okay in the past though, this is likely not an issue, but it is something of which to be aware in case something does not behave as it should with everything else in order.

 

[Challenger RTA]

Ensuring that the throttle plates completely shut with the throttle closed ensure proper alignment.

That is way I was showing the photos. It was a question that I needed an opinion on. The linkage was stopping from closing all the way. Unbeknownst to me that wasn't correct. What I think is closed but it's not.

noted by Rick, is that the throttle plates are too far open at idle,

It looks like from what I see this is the problem. Secondary link needs adjusted.

pump is stock, or stock pressure

Fuel Pump, Mechanical, Strip Super Series, M6270 8PSI. I do have to check it.

Building the 9103,

That is something I want to do any how. There are a few pieces needed or replaced. Secondary air door spring broke and a Secondary link missing. Might find it.

Drilling the throttle plates

That is something I might have to do because of the build, Thinking it is just a matter of correcting errors in the carb or myself.

Drilling the secondary plates can get around it.

Drilling the secondaries is that an alternative or in addition too drilling the primaries? Question. Does it matter where to drill the primaries or secondaries. Thinking the font area of primaries any location on the secondaries recommended.

More initial timing advance

This seems to come back and haunt me. When I was getting the cam. A more versed person change my mind on the cam. Explaining the build and use I was doing. The original build called for 2° adv key. He said the cam was to be installed straight up and it wouldn't matter either way as per instruction. Heads and deck milled too. So I was more so concerned about valve clearance. The engine does run very well.

Using full manifold vacuum

That is something I have to try. If I recall right that's how all cars where set up, Up until the 60s ish. Being about 14 years old. A neighbor had a 69 or 70 Cougar Eliminator 428. He bought it new. Keep it in pristine condition. His tools were laid out and clean like a surgical tray. Found out years later that's kind of what he was. He started having trouble at the track. He should me about ported and manifold vacuum. He could get to run good on manifold but ported it would stumble. Found out there was a intake leak somewhere. Covered under warranty.

I prefer ported vacuum advance for regular operation.

That where I was thinking. But might be or not be correct for my build. As Bill explained it to me The ported vacuum would have a more behaved drive habit. And also be better on fuel mileage. But it's more of the EPA thing about getting the lead out. This stuck in the back of my mind. Why not have the best of both worlds. Have vacuum switch Adj or preset to change when you want. I think somebody probably did that. Now they call them Computers.

by leaving the rear port for the air cleaner open

That is something I came across reading else where. Some where suggesting using a aquarium filter or valves for that. Kind of a controlled experiment.

6319 seems to have been though a mass rebuilder operation

It does move smooth and no hang ups. If it is rough it could hang up. Checked for play. Also looking into bushing the shafts just to do it later. I have two to deal with.
I responded to Rick.

This carb was on a 383 challenger I had and it worked okish. Just drove it.
But it was a rebuild from an auto parts store back in the late 80's. Transfer slot exposure. So that means the linkage was not set up. right from the get go. Thinking it was correct./\ What picture are you looking at. Some are from the top side.

I did recurve the distributor.

Thanks to Funk and Wagnalls or Audel's it might have been. I found out the basic of a carburetor. Behind the garage there was about a 1/2 acre lot or more that I always push mowed too. There was a Reel mower self-propelled that came from an auction lot. My father said it didn't work. I made it work! Pulled the glass bowl off and cleaned the carb and away it went.

I do apricate the very informed responses.

 

[Vaanth]

That is way I was showing the photos. It was a question that I needed an opinion on. The linkage was stopping from closing all the way. Unbeknownst to me that wasn't correct. What I think is closed but it's not.

It looks like from what I see this is the problem. Secondary link needs adjusted.

The secondary link adjustment is for when the secondary throttle plates open in relation to the primary throttle plates' position. At any primary position less than that point, the secondaries should be fully closed. If they are not, then the link might need to be tweaked, or check for throttle binding.

Fuel Pump, Mechanical, Strip Super Series, M6270 8PSI. I do have to check it.

The 1973 340 6319S application's fuel pump pressure was specified at 5-7 PSI. The 440 high performance in 1973 was specified as 6-7.5 PSI. Thermo-Quads in general operate fine in this range. 8 PSI is on the high side of the specification, but should not be an issue unless the pump is generating much more pressure, or a needle/seat sealing is weak.

That is something I want to do any how. There are a few pieces needed or replaced. Secondary air door spring broke and a Secondary link missing. Might find it.

That is something I might have to do because of the build, Thinking it is just a matter of correcting errors in the carb or myself.

My 1977 Fury police car with 400 high performance had its original Electronic Lean Burn and 9103S in place, never touched and unmolested, but very dirty, when I got it in 1986. It ran okay, but I converted the Lean Burn to regular electronic ignition, before Chrysler started providing instructions to do so, and added the vacuum advance port to the 9103S. I later swapped it for an earlier Thermo-Quad, but it ran fine. I had changed the metering rods in tuning it, but the original jets were good for it.

Drilling the secondaries is that an alternative or in addition too drilling the primaries? Question. Does it matter where to drill the primaries or secondaries. Thinking the font area of primaries any location on the secondaries recommended.

Placement or drilled holes is not critical, but to maintain the best venturi flow/vacuum signal, drill in the upper front, primary or secondary, similar to this image:

This seems to come back and haunt me. When I was getting the cam. A more versed person change my mind on the cam. Explaining the build and use I was doing. The original build called for 2° adv key. He said the cam was to be installed straight up and it wouldn't matter either way as per instruction. Heads and deck milled too. So I was more so concerned about valve clearance. The engine does run very well.

Ignition timing advance was my reference, not camshaft timing. Camshaft timing is not really involved here, so whether it is straight up or advanced would have little direct effect on carburetor idle, although advanced would boost bottom end, and place your tuning a bit differently on the engine's torque curve. Don't worry about cam timing here. You may need more ignition timing initial advance to get idle control where you can close the throttle plates further, but you may need to adjust your full combined advance (initial + centrifugal + vacuum) for running and avoiding detonation. With your camshaft and rocker changes, variation to a stock approach is needed.

That is something I have to try. If I recall right that's how all cars where set up, Up until the 60s ish. Being about 14 years old. A neighbor had a 69 or 70 Cougar Eliminator 428. He bought it new. Keep it in pristine condition. His tools were laid out and clean like a surgical tray. Found out years later that's kind of what he was. He started having trouble at the track. He should me about ported and manifold vacuum. He could get to run good on manifold but ported it would stumble. Found out there was a intake leak somewhere. Covered under warranty.

That where I was thinking. But might be or not be correct for my build. As Bill explained it to me The ported vacuum would have a more behaved drive habit. And also be better on fuel mileage. But it's more of the EPA thing about getting the lead out. This stuck in the back of my mind. Why not have the best of both worlds. Have vacuum switch Adj or preset to change when you want. I think somebody probably did that. Now they call them Computers.

Both manifold full vacuum and ported vacuum approaches have been used to effect similar benefits in the past. Distributor vacuum advance is a driveability enhancement to improve cruising fuel mileage, and engine response at cruise. Both methods can work in their respective areas when the rest of the system is tailored to use one or the other. Chrysler vehicles have generally used ported vacuum. Chrysler's Electronic Lean Burn and Electronic Spark Advance, or Electronic Spark Control, took over control directly of centrifugal + vacuum advance so it was completely variable and controlled, and things evolved for spark advance from there.

That is something I came across reading else where. Some where suggesting using a aquarium filter or valves for that. Kind of a controlled experiment.

It does move smooth and no hang ups. If it is rough it could hang up. Checked for play. Also looking into bushing the shafts just to do it later. I have two to deal with.
I responded to Rick.

Thanks to Funk and Wagnalls or Audel's it might have been. I found out the basic of a carburetor. Behind the garage there was about a 1/2 acre lot or more that I always push mowed too. There was a Reel mower self-propelled that came from an auction lot. My father said it didn't work. I made it work! Pulled the glass bowl off and cleaned the carb and away it went.

I do apricate the very informed responses.

I still have our Funk and Wagnalls encyclopedia set with the, annual updates through the mid 70s, and my Audel's books although most of those are for electronics.

 

[Challenger RTA]

I still have our Funk and Wagnalls encyclopedia set with the, annual updates through the mid 70s, and my Audel's books although most of those are for electronics.

Everything above clears up what I needed to know and very helpful. Nothing like hard school learning. Pick up a book and read it!

 

[Ricks72Chlgr440]

Everything above clears up what I needed to know and very helpful. Nothing like hard school learning. Pick up a book and read it!

As an aside, I put an Edelbrock street performance pump on my engine and the engine ran very rich. At the same time I installed the Dakota Digital instrument cluster and got the fuel pressure sensor put in. The pump was supposed to not need a regulator as it was factory set at 6 PSI. When I got the engine running after the sensor was installed it was at 11 PSI! Needless to say, a regulator was installed to bring it to 6.5 and all is good now. You just never know...

 

[Challenger RTA]

You just never know...

I'm not going to give you hart's eyes! Thanks!