Sdriche
Well-Known Member
My secondaries do not open full vertical as a result of the shaft end hitting the choke spring. Any help on how to remedy?
TQ secondary not opening up all the way
- Thread starter Sdriche
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81 to 88 degrees depending on applications
If need be, bend the secondary air flap on the drivers side. This will lean out the carb FWIW.
TQs don't open full vertical anyway. Buy a book and read it...... Let the roasting begin.....
Sdriche
Well-Known Member
Saga continues, The vacuum Choke pull off doesn’t seem to lose vacuum at throttle. It’s connected to the rear of the carb and seems to pull vacuum all the time. This may be part of the issue. Does the choke pull off vacuum go to manifold or carb?
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Vac choke? I am assuming you are referring to the dashpot mounted on the pass side, rear of carb. Various names used for it. It plugs into a port in the carb base, the port closest to the dashpot. Some of those ports are a brass tube with a very small hole in the end, about 0.015" diam. Would not take much to block the port.
To test: remove the hose. Push dashpot plunger in with screwdriver tip & let go. It should return fairly quickly from internal spring pressure. If this fails, dashpot is faulty & needs replacing. If OK, connect hose to port & re-test. Plunger should return; if it doesn't the port is blocked.
To test: remove the hose. Push dashpot plunger in with screwdriver tip & let go. It should return fairly quickly from internal spring pressure. If this fails, dashpot is faulty & needs replacing. If OK, connect hose to port & re-test. Plunger should return; if it doesn't the port is blocked.
Roast my ***, you're dead right. lol
Trust me, the vacuum drops out as the throttle is opened under load.
jos51700
Green Bearing thread connoisseur
Correct, vacuum drops as throttle opens.
The air door on the secondary doesn't open all the way because the flap serves to create enough vacuum (not technically, but....) to draw fuel into the carb.
I don't think it's correct for it to stop against that shaft spring though.
You said it right. The air door does create vacuum....or I guess more "technically" a low pressure area that allows atmospheric pressure to "push" fuel into the secondary venturis. That's close enough to dang vacuum for me. lol You're also correct in that the linkage does not limit the vacuum door opening. That is handled by a bendable tang on the driver's side of the secondary opening. The tang is bent to limit how far the door opens.
Sdriche
Well-Known Member
I do appreciate all the help. I have read and watched a ton of content before deciding to ask for help here. Some of the details aren’t covered anywhere so for those who shared their experience I’m very grateful. I now have some tinkering to do. Found 2 ports on the back of the carb, one has vacuum at idle and the other does not. The carb appears to be rebuilt and in great shape. The dropout looks brand new but I’ll vacuum test it. Thanks
jos51700
Green Bearing thread connoisseur
The one without vacuum is what you want for vacuum advance. A lot of people screw that up.
And for the record, in your original post, you're looking at the air door, not the secondaries. The secondary throttle blades are in the very bottom plate of the carb, and are about a large as the average manhole cover. The primaries in the same plate, and are ~1".
The secondary throttle plates SHOULD go fully vertical. The air door will not.
Sdriche
Well-Known Member
Yes sorry air door is what I'm trying to figure out. If it doesn't go vertical then I'll stop now. I was under the impression it had to go full vertical. I was told the carb port closest to the dropout was the vacuum but that's the one without vacuum. The center port did have vacuum. I'll leave the dropout on the vacuum port and move the vacuum advance to the right port too. Thanks again
Keep messing with it. That’s how you’ll learn the carb best and what works on YOUR COMBINATION!
No the rear butterflies were never designed to fully open vertical. They direct some air and fuel towards the front of the intake to balance out the air fuel ratio as the front butterflies are very small. It is not a GM quadrajet. Kim
Ether way. Let’s just call it darn close to straight.
jos51700
Green Bearing thread connoisseur
That's the silliest reason I've ever heard for factually wrong info.
First off, the secondaries have nothing to balancing air fuel ratio. Either the primaries are correct on ratio or they're not, and ditto the secondaries. That's what jets and accelerator pumps are for.
Second, directing airflow is an intake manifold job, not a carburetor job. If you ever changed intakes, how would you know how to adjust this to match the intake?
Third, HOW MUCH from vertical should they be? Oddly, Carter provides an adjustment method, right next to the spec of 90 degrees, but no spec for any other angle is listed, nor is there any way shown to measure it.
4th (Edit, I was wrong on this one)
From the Carter carburetor manual section on TQ's (which is also the same spec as all other Carter 4-barrels including the WCFB, and every four-barrel I've ever seen):
And FYI, the 90 degree spec is also the same on Rochester Quadrajets, as installed on Chrysler vehicles, too.
Go readjust your TQ's and pick up some ET's.
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Here is the linkage from my original 6090s TQ from a "72" 400 that was on my "68" Formula S 383 that ran flawlessly hot or cold. Looks like you have a hodgepodge carb, so who knows what you have other than a 6090s base. What is the top casting number? Do you have a secondary adjusting tool? Have you checked jet and rod numbers? I'd ditch that banjo fuel inlet also, and get a 5/16 brake line and run it straight in. As I remember, secondary angles were different between auto and manual carbs. Do you have an adjustment sheet for the TQ? Take the time to make all the adjustments called for including the air valve gap dimension between the air horn and the secondary air valve. Pictures 4 and 5.
I believe he was talking about the air door above the secondary butterflies when it comes to angle, I’m not sure. Though adjusting the secondary air door will effect the rich and lean conditions on the secondary side.
Well, that was just my thoughts on it. I have been wrong b4. I have at least ten TQs and not 1 opens vertically. U can’t get the same amount of flow from the little front barrels as u can from the rear. KimThat's the silliest reason I've ever heard for factually wrong info.
First off, the secondaries have nothing to balancing air fuel ratio. Either the primaries are correct on ratio or they're not, and ditto the secondaries. That's what jets and accelerator pumps are for.
Second, directing airflow is an intake manifold job, not a carburetor job. If you ever changed intakes, how would you know how to adjust this to match the intake?
Third, HOW MUCH from vertical should they be? Oddly, Carter provides an adjustment method, right next to the spec of 90 degrees, but no spec for any other angle is listed, nor is there any way shown to measure it.
4th (Edit, I was wrong on this one)
From the Carter carburetor manual section on TQ's (which is also the same spec as all other Carter 4-barrels including the WCFB, and every four-barrel I've ever seen):
View attachment 1716075483
And FYI, the 90 degree spec is also the same on Rochester Quadrajets, as installed on Chrysler vehicles, too.
Go readjust your TQ's and pick up some ET's.
jos51700
Green Bearing thread connoisseur
You're damn right. Nothing sounds better than a TQ through an unsilenced air cleaner.
Kimmer,
You got it right in post #15. The huge sec throttle blades have a large directional effect on air flow/distribution into the intake. The MP bulletins recommended a 81* WOT angle for the secs on dual plane intakes & 88* on single plane. Pontiac engines used the QJ which have the same 2.25" sec blades; getting the WOT angle wrong can cause rear cyl to run lean.
You got it right in post #15. The huge sec throttle blades have a large directional effect on air flow/distribution into the intake. The MP bulletins recommended a 81* WOT angle for the secs on dual plane intakes & 88* on single plane. Pontiac engines used the QJ which have the same 2.25" sec blades; getting the WOT angle wrong can cause rear cyl
SD,
Did you read what I said in post #6? The vac port at the carb rear, nearest to the A/valve dashpot is where the dashpot hose connects.
The a/valve blade itself has a notch in the drivers side & that is what you bend to give you the correct WOT position of the blade. I have found the position is not critical.
You need to do the test in post #6 to make sure the dashpot is releasing fully because the a/valve blade will not open fully if it is faulty & the link arm also has to be adjusted correctly.
Did you read what I said in post #6? The vac port at the carb rear, nearest to the A/valve dashpot is where the dashpot hose connects.
The a/valve blade itself has a notch in the drivers side & that is what you bend to give you the correct WOT position of the blade. I have found the position is not critical.
You need to do the test in post #6 to make sure the dashpot is releasing fully because the a/valve blade will not open fully if it is faulty & the link arm also has to be adjusted correctly.
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