Hey guys
I have only had my car for a few weeks now. Im trying to get reacquainted with the 6 bbl setup. Only thing I did was manually force the linkage forward so I could see how dirty the backside of the secondary throttle plates are and tightened the screw on the fast idle lever cuz it was loose.
At startup, it went right to 1500 rpms and steadily increased from there to almost 4k until I just cut it off. It did it fast too...in like 30 seconds.
I tried WOT to get it to come back to regular idle and that did nothing. Also messed with the fast idle lever and cam to try to get it to reset...nothing.
What would cause that?
Thnx

Sounds like one or both of the outboard carbs is partly open at idle. Disconnect the linkage at the outboard carbs then make sure their throttle plates are completely close. Restart the engine and see if that makes a difference.

Good advice, but didnt work.
Its almost like there is throttle input without me giving it throttle.
No leaks that I can tell. Would have to be a pretty huge leak.

Could you have the vacumn line for the end carbs hooked up to the wrong source?

I hadnt changed the vacuum lines to the secondaries. But its coming from the nipple near the base plate of center carb

The small angled one out the side of the front, not the PCV one on the side.

Ok, I got it. I unhooked the secondary linkage but still had vacuum to diaphragms. Unplugged those and reset curb idle. All is good.
I didnt thi k the vacuum would be enough to open without the linkage connected. Now I know Ive got good vacuum at least.
So, the other day I checked to see what springs I had in there. Plain. I must have put them back in wrong? I dont see how, only one way to go in.

That linkage is there to CLOSE the outboard carbs, not open them. They are opened by vacuum. Your vacuum hose needs to be connected above the throttle plates, if you have it connected below the plates you're getting vacuum to the outboards at idle, a NO, NO.

And here is the correct hose routing.

Yup, routing was wrong. Makes sense now that I have a minute to think about it. All that manifold air going to the secondaries would cause them to open at idle. Whereas vacuum from up top (where it was supossed to be) would be from the main venturi. Totally different circuits.
So I gotta assume the angled nipple at the base vacuum goes to choke pulloff right? Hard to see that from your pic.
Thanks for clearing that up.
As I said, the car is new to me so Im just going thru it trying to find any faults, etc.
Its still weird to me that it did it now and not before. Maybe the secondary werent getting vacuum before or the springs were binding? And when I checked on them, it freed them up?

Choke pull goes to base, vacuum advance to metering block,all other to main carb body.

The vacumm that opens the end carbs is generated by airflow velocity thru the venturi's of the center carb. It is totally seperate and unrelated to manifold vacumm. The vac line to the end carbs hooks up to a nipple on a boss that is integral to the body of the carb. Like someone said, Base plate goes to choke pull off diaphragm, metering block to dist advance. If you think about it, if the end carbs worked off of manifold vac, they would work in reverse,as we all know manifold vac is high at idle and very low at full throttle. Enjoy your six pack!