[Kenth]

A hole at that location is a Chevy deal with a vacuum tube in it for the air cleaner hot air valves.
No Pontiac Q-jet used this hole/tube.
Pontiac Q-jets has a guide for the pull-off bracket instead of the tube.
What is the stamped application number on your carb?
What is the cast number in the little ring back on the float bowl?
If you have a "Frankencarb" you may have a massive vacuum leak there.

Not all makes/years Q-jets used the spring on the spring on cam follower lever.
1968 and later Pontiac does.

[sglemans]

The number on the side is 7028262 same as my original qjet will check the air horn number. If this is a Pontiac carb then it has an open hole on the side?

[sglemans]

How would that hole be fixed if necessary? Could it cause running issues such as hesitation or surging, or affect the choke? I wonder if it was always like that or the pull-off bracket mount just fell off at some time

[MPKind]

In the old Service Manuals, like the 1970 Pontiac one I was looking at, it says close the choke valve, then hold the coil rod to the upper limit and bend as needed to fit the notch on the follower cam. Says the same thing in the 73 Motor's Manual. I don't see how that's possible. I close the choke and pull the coil rod up and it goes a good 1/2" or more past the notches. I have the rod with the "U" bend in it. Seems too long to be adjustable. I'm sure there's an explanation, but I can't figure it out. Looks like the cam follower design didn't really change much from '67-'72. Appears the notches and the coil rod hole are clocked in the same position.

I'm running a '68 intake with a 7041262 ('71 455 std carb). I have cold start issues where it won't close the choke and move the cam to fast idle with command. I have hot start issues where it won't pop off nice, runs rich right away. So I thought it was the stat spring, I have others similar and it's good. Right now I'm using a 9097 or 0097, difficult to read. A shorter rod my improve the choke action and hold it open better when hot, instead of pulling it closed because it allowed the spring to fully expand with minimal resistance.

What am I missing here? Seems like the parts I have should work together, but they don't. They fit nice, but the operation is all wrong.

[Schurkey]

Originally Posted by MPKind

I have cold start issues where it won't close the choke and move the cam to fast idle with command. I have hot start issues where it won't pop off nice, runs rich right away.

Without photos of the carb and chokestat, and illustrations of the factory service procedures, I'm gonna go way out on a limb and say that the chokestat needs to be tightened (richer) and the choke pulloff needs to be adjusted to pop the choke blade open a little bit more.

[MPKind]

The stats don't really adjust...you can force it I suppose. Pic included. This is more of a parts mismatch than anything, I think.

[Kenth]

Try this:

[MPKind]

Kenth, that’s the procedure I described. I can’t get that to happen. The rod lands a good 1/2” above the notches.

Looked at what a new choke rod looks like. The one attached to the choke. Mine appears to have too much bend in it which sets the cam follower more clockwise than it should be. If I put a straighter rod on it then maybe the stat coil rod might align as it should.

Ordering new parts today.


Sent from my iPhone using Tapatalk

[MPKind]

Choke rod was too short. When fully straightened it just barely is at 2.5”. Outer choke rod sits in the R notch now. So I’m a lot closer than before.

[MPKind]

More questions than answers. The stat rod setting and the choke rod setting of 0.100 air gap are not jiving. I set the stat rod, but then try to set the choke rod to get 0.100” opening and it brings it back to where I started. It’s a similar to a 67-70 4MV setup.

To make the choke rod gap it rotates the cam follower to where the choke coil rod becomes too long. Make the choke coil rod at index and the choke rod gap is 0.250”.

It could be a couple of things. Worn parts that add extra slop to the action and/ora thin carb to manifold gasket. Probably both.

It’s weird that it’s way off

So bonus points if you know what the 0.100” gap on the second step of the fast idle cam does for you during warmup. Frankly, I don’t know WTF it does. I ask to determine how important it is to the whole start and warm up process. I think it’s more important to get the choke coil to open up from the correct index point and provide a commanding choke close on a cold start. It also keeps the valve more wide open for hot starts.

So far giving the choke rod opening priority has not worked out.

[Sirrotica]

You need to get a manual, or a set of instructions that come with a carb rebuilding kit and use all the settings listed.

Each carb has a set of adjustments, that must be done in a sequence. The adjustments are given in thousandths of an inch, or degrees tested with an angle gauge that has a magnet that adheres to the choke blade butterfly.

The fast idle cam adjustment is usually done on the car with it fully warmed up. and running in neutral on the second notch of the fast idle cam. You need to have a tach that can be read from under the hood. I'm just picking an RPM that I remember from doing these adjustments, 1600 RPM is a common number, but these vary by applications.

When you have all of the adjustments made, as per the manual, instruction sheet, the car will start and run as good as most any modern fuel injection system, but you have to do all the adjustments in sequence, and not skip any of them. It takes time to set them all, but you'll be rewarded with a flawless cold start, and warm up.

I have a Kent Moore kit that has all the pin gauges, as well as the angle gauge. You can also use drill bits to set the choke blade to air horn gaps. You also need a vacuum pump to set the vacuum break/choke pull off.

Previously I worked in GM dealerships and have gone to GM training schools for carb repair/rebuild. this is where I was shown the correct way to rebuild Rochester carbs. Just bending linkages, and turning screws won't get you to where the car starts, and runs as it should, it's a precise set of adjustments that make it do everything correctly. The engineers spend a lot of time getting these adjustment setting within thousandths, eyeballing them doesn't work most times.

The choke is closed, and the screw is on the highest cam portion, when it starts it goes to the second step of the cam when the choke pulloff partially opens it. The RPM setting on the second step is crucial to the operation to run, without stalling.

Over the years I've worked on many divorced choke Pontiacs, and the Q jet linkage must be the correct length, as well as the tension on the choke bi metal spring. All these things dovetail together to make cold starts seemless, but if one thing is off, it throws everything off. This is why ALL of the adjustments need to be made according to specs, and in the correct sequence. FWIW, most aftermarket choke stoves for Pontiacs don't have the correct spring tension, or opening rate in my experience.

I tried to fid a video of how the fast idle adjustments are made properly, this is just a very basic video on how, and why the adjustments are made:

https://www.youtube.com/watch?v=-LUT...drajetPowerLLC

I wasn't able to find any videos of detailed settings of how the choke, or fast idle settings are made.

This may be of some help, but again no specific settings, just guessing where the settings need to be:

https://www.youtube.com/watch?v=srr4...DCIMotorsports

[Kenth]

Follow these instructions:

[Kenth]

Be sure to pull the little springloaded plunger when setting choke pull-off:

[MPKind]

1. I have been using the procedure from the 71 Pontiac Service Manual with specs.

2. I always use drill index for measuring.

It’s an old carb so there’s some wear that makes its function less precise. What I discovered is that the stat coil rod is too long to properly index when the inner choke rod is properly adjusted to 0.100” air gap. Again, I don’t know what that 0.100” gap does for you on warmup. The cam follower rotates CW and you end up with the stat coil not able to work properly.

I am using OE parts. The only thing tha would make up the short length is a thicker carb gasket. Then I can get the choke rod setting and the stat coil rod setting both set instead of going in circles

[Sirrotica]

Make sure you have a 4bbl rod, and not a 2bbl rod, they are different.

[MPKind]

It’s a 4bbl rod. The one with the U bend in it. As you can see I’ve squished the U bend down so it works the choke better.

The inner choke rod is straight

The whole where the outer rod connects rotates CW when the inner rod is shortened which make the stat coil more unwound. This is how it’s been.

Today it popped off instantly. Also started well when it was hot after sitting for 30 minutes.

Overall function is improved, but the stat spring rod is still not topped out when cold. It’s just too long for this setup.

My guess is that the whole the rod connects to may be clocked more CCW on the 67-70 carbs, which are the matching parts to this coil spring and rod. I don’t know for sure.

Also. The notch indexes don’t really work with the U style spring. It doesn’t want to bend that way to set it in there. Seems forced to do it that way. The 71-2 coils were 90* from mine and could utilize the notches.

My conclusion is there’s a couple mismatched parts that prevent proper adjustment.

The other pic shows that the outside choke lever is hitting the stop. It looks like the stop could be bent to move the outer choke rod hole more CCW.

[MPKind]

The rod will tilt some to use the notch index. Just barely.

The choke rod setting in the diagram can’t be achieved once the outer coil rod is set. If you bend the inner is messed up the outer rod setting.

When the fast idle cam moves from the hi to middle step it appears to open the choke about 0.1”. But worn parts make it larger. So it think it’s been optimized at this point with what I have.