I recently replace my 307 with a 403; wanting to keep all things (except the A.I.R. system) functioning and the transmission shifting, etc. I decided to retain computer system and hence the computer carb off the 403. I had the carb rebuilt and jetted to feed the 403. The carb shop just went out of business due to Hurricane Ike (after 20 years) a week after I got my engine swap (403) completed and running. Problem I am having is the 4bbl will not kick in whether driving or in park. I am not sure if I have a linkage problem or not; possibly a vacuum problem? I took pictures of the linkages though I don't know how I could post them on this site for review. Anybody have any ideas or where I might go to resolve the issue? Possible site or book with pictures showing linkages?

Assuming you mean the secondaries do not open:

By design, the secondaries are only used when the primaries cannot meet the flow demands of the engine. In park (or in neutral) it is not possible for a 403 to "demand" more flow that the primaries can provide.

Which trans do you have?

Norm

Transmission is a 200-4R Automatic Overdrive.

The detent cable is in place and is operating correctly; the transmission shifts properly and the shift points remain as they were on the 307. (apparently I didn't jar out of position the detent cable during the engine swap so that's a plus)

It used to be (on the original 307 and on other older Rochester Quads on my other cars) that at idle and at operating temperature that I could WOT and the secondarys would operate and the airhorn secondary butterfly would open up partially. So this is why I think it isn't operating properly as I can't get it to activate at idle. In addition, while driving, it will not open up and there isn't any response when I am traveling at any speed and I floor it...can only gain speed at mild acceleration; WOT just doesn't occur...no bogging...just no response.

Send them to olds88coupe@yahoo.com and I'll post them, temporarily.

1, The choke is not fully open.

2. The stop, at the bottom of the choke rod, is not releasing.

3. the secondary throttle valves are not opening.

Re: #2. If one of those images, is the right side of the carb, showing the lowest part of the choke linkage, it would be helpful.

Norm

While warm and at idle and also when shut off warm and manually manipulated, the choke is fully open; the secondary throttle linkage operates freely and the secondary lock-out (activated by choke openess) is working properly where the lock-out is pulled away when the choke opens and doesn't restrict the secondary throttle butterfly.

It appears to me that on the driver side of the carb there isn't any mechanical way of the secondary throttle butterfly to open (not the top airhorn butterfly valve). Only when I manually manipulate the secondary shaft via linkage (on the shaft itself) will it open. It will not open when manipulated with the throttle cable or with the primary linkage travel. There appears to be a tang on the primary throttle butterfly shaft that would open the secondaries once the throttle was activated closer to the floor or wide open if this tang was rotated on the shaft about 15 degrees...so that this tang would then in the travel of the primaries actually engage and press against a portion of the secondary linkage and begin to open the secondaries... Like I said...there isn't anything mechanical that actually operates the secondaries. Due to the springs and the design of the secondary shaft I can operate via hand but it will not operate via cable or in normal operation. I have heard of vacuum secondaries but am not sure that would apply to the Rochester QJ. If so, maybe it is a vacuum problem. The vacuum does operate the secondary airhorn butterflies correctly by holding them until vacuum loss under heavy throttle (though that isn't happening this moment) as it does stay stoutly closed until a loss of vacuum occurs (pulling off the vacuum tubing). I will try to get some pictures of the driver side as the passenger side and choke apparatus all seems to be correct.

Does the (circled) rod move with the primary shaft?


That would be "venturi" vacuum, as used by Holley. Not used by Q-jet, thermoquad, AFB (or its Edelbrock clones).


Vacuum holds the air valves closed?

Do the they stay closed when the engine is shut off?


Which vacuum tubing?

Norm

I finally figured out the issue.

The tang on the primary shaft is to engage and cause the secondary shaft to operate (as well is the upper linkage rod you circled) once mid-stream of throttle is achieved. Found that the throttle cable was not extending far enough for that to occur as the transmission detent cable was interfering with an intake manifold bolt head.

The intake manifold is an edlebrock performer and is very close to stock so not sure if the thickness at that area where the bolt secures the intake to the heads is thicker or more elevated but the bolt head protrudes at an elevation that the crimp nut on the detent cable clip (plastic clip with metal crimp nut in front of it on the cable) is hitting the manifold bolt and doesn't allow the throttle to open any farther.

I was able to (by hand) twist the plastic clip (attaches to the carb linkage) so that the crimp nut was able to pass by the manifold bolt and voila! The secondaries engaged and all is good.

The only thing now is to figure out how to modify the crimp nut end to clear the bolt or to modify the bolt or change the bolt out with a smaller or less thick head.

I appreciate your help and efforts immensely. This has been a puzzler. Just never saw the detent cable having the interference...

Glad you found the solution.

Norm