HELP! 66 cuda idles fine, but not when in gear

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So in the last pic, swap the two small hoses?
Yes, the vacuum fitting at the top of the carburetor is for those with emissions controlled engines such as if you were still running the stock lean burn distributor. In those engines, you have to run it at the high point because if you don't it will have too much advance at idle and burn up because the distributor is already set differently. when you're setting up a performance engine without lean burn and without emissions controls, you use the vacuum port at the bottom for full idle advance. That is also why your engine runs well at off-idle, but not full idle. That was the give-away, after reading your description of symptoms I immediately went down to the pictures hoping I would see a clear view of where you had that idle advance hose plugged in to.
 
And if you want to get best use of the V-can;
rotate the Distributor exactly two towers CW, and then rewire the cap Exactly two wires CCW. Then reset your power-timing. Now the Vcan has put the D into a position for easy timing changes.
It's not real important but if you open your hood at a car show,like it is, your newbe status will on display.

After you plumb the Vcan to the Sparkport, you will need to reset the timing and reset the idle-speed.

Ima guessing the other valve cover has a 2-way breather on it?

The hose on the PCV should be specifically for that. If yours is fuel-line, the engine will suck that flat while cruising.
 
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Ported vs. Manifold Vacuum

If you can forgive the blasphemy of posting Chevy stuff, this is a good explanation of the ported vs. Manifold vacuum for timing that I was talking about. I also second what AJ said, I had to do the same with my distributor. after I got the timing set it was putting the canister right against my plenum.

Screenshot_20190912-005423.png
 
That was a great read. Makes sense and appears(hopefully) my main culprit for a couple issues is vacuum lines hooked up to the complete wrong spots. My brakes don’t have great vacuum either and seeing as it is not on manifold vacuum, that might be the reason. Can’t wait to switch these vacuum lines after work and see the results. Thanks everyone and I’ll update when I’m done!
 
Mini update, I checked the vacuum hoses and the vcan hose actually IS going to the spark port on the carb. The picture is misleading as both vacuum hoses run under the carb and you kind of lose which one goes where while looks at it. So I adjusted the mixture screws out, and played with the idle with no change.
 
Well I reread what Blackhatguy said, I think I read it wrong the first time so I’m going to swap those two hoses and see
 
After swapping the vcan vacuum hose off of the spark port and on to the base plate i took it for a spin, and there is a noticeable improvement. Don’t have full confidence it won’t stall as it still is a little rough, but it is much better
 
That was a great read. Makes sense and appears(hopefully) my main culprit for a couple issues is vacuum lines hooked up to the complete wrong spots. My brakes don’t have great vacuum either and seeing as it is not on manifold vacuum, that might be the reason. Can’t wait to switch these vacuum lines after work and see the results. Thanks everyone and I’ll update when I’m done!
Unfortunately its wrong. Its not even factually true.
Go look at '67 or earlier shop manual. Then go look at a '68 and newer.
Or do a search here. I've posted this stuff before.
All that is irrelivant to solving your cars issues.
Use whatever it takes to get the timing neccessary for the conditions. The goal is maximum power through the angles of maximum leverage on the crank.

You can crutch it idle with adding more initial using the manifold vacuum. The question will be if there is enough vacuum in gear to get away with it.
Don't add more timing than needed to get a relatively rich mixture to burn well.
 
I adjusted the mixture screws out, and played with the idle with no change
If there is no response to adjusting the mixture screws then its likely the primary throttles are open too far.
 
Nah, if that's an MSD distributor, my bushings are a byunch less $'s.

:)
Yea. If thats an MSD or any non-Chrysler advance for that matter, those FBO's plates won't do any good at all.
 
Also with that cam, 16* at idle would be minimum, maybe in 408. IMO 18* -20* will be closer to ideal depending on the heads, compression, etc.
Distributor starting point for a curve

That's 18* from 0 to maybe 900 rpm. Should be able to get it to idle around 900 rpm give or take some when its warmed up and choke is off.
 
Since your under a time crunch, get it to idle correct.
My suggestion is plug the vacuum advance hose (golf tee, just like when you set the timing).
Set the timing for 18* or 20* and get it to idle as slow as it will tolerate.
Once its warm,
Adjust the mix screws. Turn in until it starts to die, turn each back 1/4 turn. (CCW so its richer than when it started to die).
See if it will idle in gear.
If so, leave it that way and try driving it.
If its OK...
Put fresh plugs and tell them if they floor or otherwise pound on it, they owe an engine. You have a contract, right?
This way if there is too much timing for higher rpm, WOT, you'll know by seeing shiny specs of aluminum on the plugs when you get it back.
With no vacuum added advance, there should be no problems with part throttle timing. Fuel milage and efficiency will be less than ideal, but it will run.
 
For a streeter; that's all I know about:
All well and good, but modern carbs have the transfer slots engineered to run with the ported spark.
On street engines, if you try and run NON-ported spark, and simultaneously have the timing cranked, almost invariably the throttle blades end up too low on the transfers, and you crank the mixture screws out to compensate. Ok great it idles.
Then you put it into gear, and airflow falters and the engine throws a hissy-fit. If you manage to keep it running, then you get a tip-in stumble as the transfers come on line.
So then in desperation you start throwing timing at it, and the idle speed goes up. And then you reduce the idle speed with the speed-screw; Making it worse; probably again.

The thing for a newbe to keep in mind is that the idle fueling is determined by the 1-2 punch of transfer slots plus the idle trimmers. Those mixture screws are trimmers for making the engine rich enough to idle on.They are not there for the engine to idle on by themselves.
The lowspeed circuit is actually the transfer slots, trimmed by the mixture screws.
So if at idle your mixture screws are ineffective, then the transfers are doing all the work.
But if the mixture screws are out to double their mid-point, then the transfers are not supplying enough.
At idle you can play these two off eachother to get a nice smooth transition to off-idle. And this usually solves the stumble when putting it into gear as well.
So what about the timing?
Well, with an automatic; who cares! the engine doesn't have to pull at idle, it has a fluid coupling! All you have to worry about is that by stall speed, the timing is back to where it needs to be.
So then if that is true, then after you have the relationship between the transfers and the mixture trimmers dialed in, THEN, you use the timing to set the idle speed. And finally, you introduce idle-bypass air, if your cam calls for it, to clean up the exhaust and or smooth the idle out. But be wary of adding too much air on a rich idle...... cuz the idle-speed will go up, and then you will have to take timing out. Cuz you already established the T-slot to trimmer relationship, and can no longer use the speed screw.
And round and round it goes.

So what is the answer?
Understanding is the answer.
Every engine will have a desire for a unique T-slot exposure to trimmer relationship, and modified by how much idle bypass air it is getting. The initial-timing is only used to set the idle-speed; and yes you can trade timing for bypass air.... and vice-versa, to a small extent.
Then the power-timing is established.
Then the starting and ending points of the timing curve are established.
Then the shape of the curve is established.
Sometimes/usually the above two are done simultaneously, because that's all that the factory type parts will allow, and sometimes it gets to be a crapshoot.
Now you have established, to a large degree, two things namely; 1) the power-timing for all rpms at or near exactly ONE load setting namely WOT, and 2) the idle timing/ tip-in. In other words, the timing is exactly right just two times; at WOT, and at idle; ergo at all other rpm and load settings; the timing is dead wrong.
Now comes the fun part; making the Part-Throttle/ load timing right, using the Vcan; or at least, as close as you can.

So now, where does the tune start? Answer;Establishing the T-slot exposure to trimmer adjustment.
And I always say;
On carbs with transfer slots;
Remove the carb, flip it upside down and set the Transfer-slot exposure to between square and slightly taller than wide. Square with small cams, to taller with bigger cams. Put it back on and reset the trimmers to in the center of their adjustment range. Pull in some timing and crank it up. Then back off the timing to whatever in-gear idle-speed your cam likes; typically 650 (+/-50) in gear for for most street cams with stalls around 2000 or better. Then finish up by fiddling with the trimmers.
On carbs without transfer slots, IDK.I haven't seen one in a very long time.
With a manual trans, that's a whole nuther story.
 
So the carb was running lean at idle, I turned the idle mix screws out to richen it up a bit. The mechanic who installed the motor didn’t tighten the distributor bolt enough and it affected the timing. I advanced it a little bit, and tightened everything up. Night and day difference. Sometimes it’s the little details that make a huge difference.
 
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