[jhein]

I noticed yesterday that my secondaries were not opening, previously they were working normally. For some reason my choke is staying on even well after the engine is at operating temp (180 F). The pull off is also staying on which is why the secondaries aren't opening. What I don't understand is why it was working and now it's not. The carb was built by Ray Klemm and other than adjusting the fast idle and curb idle, I haven't touched it since it was put on the car. Any ideas?

[77 TRASHCAN]

Carb number???

[jhein]

Originally Posted by 77 TRASHCAN

Carb number???

7040263

[steve25]

Your choke lock out lever might not be rotating out of the way to allow the secondary’s to open once the choke flap is wide open.
The lever might be hanging up on its shaft.

See my photo of the passenger side of the carb,

[jhein]

Originally Posted by steve25

Your choke lock out lever might not be rotating out of the way to allow the secondary’s to open once the choke flap is wide open.
The lever might be hanging up on its shaft.

See my photo of the passenger side of the carb,

This carb doesn't have that. It's just got the choke pull off.

[Sirrotica]

The only way the secondaries are locked out is with the lock out lever. Many times if rebuilt for high performance use the builder will delete the lockout arm. The way the lockout arm is designed is that if the choke isn't fully retracted/open, it locks out the secondaries. Occasionally the arm will get gummed up, and fail to drop, still stopping the secondaries from opening. Carb cleaner can be used to the dissolve the gum on the pivot.

If you wire the choke open do they open?

Divorced choke thermostats do wear out, and they require adjustment/replacement sometimes as the temper leaves the bi metal springs as they age. The factory units seemed to last the best, aftermarket replacements sometimes don't usually have the same quality as the OEM parts did.

Just a few things check to get it operating properly again.

[JLBIII]

Make sure the choke pull off rod is still in the spring, especially if it's an aftermarket unit.

[MarkS57]

Hi assume your choke assembly looks like this, maybe with the plastic pull off. The secondary lock out was removed in this pic. I had issues with the aftermarket choke thermostat. Went back to the original 1969 stat and it works as it should..after 54 years..

[steve25]

With a devorced choke the way you adjust it is with the arc of the bend in the rod up to the choke tower.
If with the motor fully warmed up you can still knock the coke flap around then the choke rod needs to be adjusted.
With this being in proper adjustment the choke lock out lever should now be off.

["QUICK-SILVER"]

Engine Off

Do a visual inspect of secondary throttle opening while someone holds the loud pedal on the floor.

Could be slipped cable, slipped bracket or stuck throttle blades.

Clay

[jhein]

Thanks for the replies. The carb is freshly rebuilt and restored. It's clean enough to eat off of. The choke rod feels like it's attached to the thermostat spring. Everything moves freely with full range of motion. If I hold the choke plate open using the rod, the pulloff stays on/locked. If I disconnect the vacuum to the pulloff, it releases fully. So as mentioned, I'm thinking the problem is the choke thermostat. Does that make sense to everyone?

[Shiny]

It does sound like the thermostat coil may not be working. Mine will fully open the choke in about 5 minutes after starting.

Have you pulled it and looked at it? The issue may be obvious. I haven't looked at mine for a while but I remember it being pretty simple.

The coil itself is a bi-metallic strip so nothing to break there. Binding or linkage issues are more likely. I don't remember if there's an adjustment (ie clamping the coil) but can look if it will help you.

[jhein]

I'm gonna look closer at the thermostat and also double check the linkage rods to make sure they don't need adjustment. Although I'm conflicted. Part of me says to just disconnect it because I don't really need it. The other part of me says It's there so I want it to work correctly.

[Sirrotica]

These are the parts your choke linkage consists of, the adjustment is made at the kink in the rod by opening, or closing the size of that loop when every thing is cold. 68-70 Pontiac Quadrajet.



If memory serves the 2 bbl and 4 bbl links look similar, but are not interchangeable because they are different lengths. The link should move up and down from cold to warm roughly the same amount of travel of the choke linkage travels, with a slight preload when cold. Maybe 1/8 th inch above the hole in the choke linkage when cold. So you can make an adjustment to the rod, but you still need the thermostatic coil to move the linkage it's full travel during the heat cycle. You need to check for full travel of the thermostat to rule out a defective thermostat first.

If you have full travel of the thermostat, adjust the linkage at the bend.

I attempted to find the directions online for the adjustment, but was unsuccessful.

This video has a few of the basics of choke operation for a chevy QJ from GM:

https://www.youtube.com/watch?v=_BTEdWt2V3s

[Shiny]

From repair manual

[Shiny]

Measurements

[Sirrotica]

Shiny, those are the instructions I was trying to find online along with the specs. TY for posting them, hopefully this will give the OP some information about choke operation, and adjustments to pinpoint his problem.

Most carb rebuild kits also come with these instructions.

[Kenth]

Originally Posted by jhein

The pull off is also staying on which is why the secondaries aren't opening.

The air valves will NOT open w/o load on engine (high vacuum).
At WOT on the road (low vacuum) they will. Low vacuum releases the pull-off.

FWIW

[jhein]

Originally Posted by Kenth

The air valves will NOT open w/o load on engine (high vacuum).
At WOT on the road (low vacuum) they will. Low vacuum releases the pull-off.

FWIW

OK, that makes sense. But, the secondaries were definitely not opening while driving at WOT. So there's something else happening.

[Cliff R]

The secondaries are mechanical so they have to be opening when you go to full throttle.

With the engine fully warmed up shut it off. Have someone go inside the car and put the accl all the way to the floor. Verify that the secondary throttle plates are opening up all the way.

Next reach up and depress the secondary air flaps to make sure they are opening all the way.

If both are opening up in this scenario they they are opening when you go all the way to the floor or WOT. You may not "feel" the secondaries "kick-in" as transition should be smooth and seamless. Even so the engine should pull up the the RPM range pretty hard right to the shift point.

If you are looking for some sort of "kick-in" from the secondaries as an indicator that they are working you may not find it. Even so the engine should rev quickly and make good power. This assumes it's in good shape and the distributor is doing it's part as well.......FWIW