68 383 with 750 carb. Runs rich
Comments inside the quote, in blue
Ok finally had a chance to put my carb back together. I did not rebuild the whole carb as the powervalve seemed suspect and had some build up around it. I installed a new power valve which came in kit as 6.5, new fuel pump diaphragm , pulled air/fuel needles and installed fresh cork seals for them and new gaskets coated with silicon spray lubricate for front block only. Also blue out all passages with carb cleaner and compressed air. Fuel float level was good before pulling apart. Didn’t take apart rear of my carb yet and didn’t realize the kit didn’t come with 2nd vacuum diaphragm parts which I’m not sure are working yet. Where I never checked timing originally I figured to take a look after assembling and see if anything changed. So car started right up with initial air/fuel at 1.5 turns out.
Checked timing and was set at 10 BTDC and 35 degrees around 2400 ish with dist vacuum unplugged and capped off. I tweaked the idle timing to 15 BTDC. Did you do this by just rotating the distributor. If yes, then the power timing is similarly advanced an additional 5*, to 40*, and I'm not sure if that's a good thing or not, cuz I'm not a BB guy . But typically 36* is the limit for SBMs and iron heads. To me 40* at 2400 or in your case 40* at stall, if 40 is the max possible,sounds a little iffy for a newbe.
My original problem was a hard hot start I will need to drive the car to see if that is gone or not and the car is too rich and it still too rich.
I did notice if I put the car in park or drive there is very little difference in vacuum Gauge readings.With a 3000 TC that sounds normal
I also sprayed around with carb cleaner trying to find a vacuum leak I didn’t. I also put both my hands over the carburetor with welding gloves and it seem the engine could just keep on running. It is very difficult to seal both the primaries and the secondaries,sufficiently, at idle, with welding gloves. With your vacuum readings,there should be no reason to have to crack the secondaries, so I would make sure they are fully closed but not sticking. Then you can stuff a shoprag in the back to seal them up, for testing purposes..
Part I
The PCV system has to be hooked up and working; it is a controlled idle-air bypass; and it is a controlled part-throttle enleanment. Without it working at idle, you will have to increase the primary throttle opening, (or crack the secondaries) to get the idle speed the engine wants.Increasing the primary opening will cause the transfer ports to be too far open, and the net result is that the idle mixture screws no longer function correctly.
And without it working at part-throttle; between the non-functioning enleanment and the possibly not-functioning mixture screws,the low-speed carburetion cannot be anything but rich.
Part I
If the PCV is not functioning properly; then the secondaries will have to be cracked to provide that bypass air. Unfortunately, on a small-cammed engine, this usually causes the back cylinders to run slightly leaner, and makes getting a decent idle quality tougher to achieve. I don't even try anymore.
The PCV should be plumbed to the port provided on the front of the carb, behind the coil. That port dumps into the primary bores just below the mixture screw ports.Do not plumb the PCV to the secondary side of the carb.
When that system is working properly, you will be able to close the primaries to a correct TransferPort exposure, and then the mixture screws will work. Then you can adjust the idle speed with idle timing. And then you will have to limit the Power Timing to keep the engine out of detonation.
Along the way, these changes will clean up your low-speed carburation, and possibly even minimize your hot-start problem.
Part II
There is a second scenario, in which even tho I cannot see it , the PCV is properly plumbed and working. In this case adding more and more advance causes the idle speed to rise too high, and with a regular TC it bangs the trans into gear,ouch! With a 3000 tho it just idles fast. So then you come along and slow it down with the speed screw, closing the throttle valves, and running them down the transfer slot, thus shutting off the low-speed fuel supply at idle. So then you would have to crank the mixture screws out in an attempt to give the engine the fuel it needs to sustain the idle. But the mixture screws have a very little amount of fuel they can add. So as soon as you tip in the throttles the now nearly dried up transfers get jolted into life, with a little hesitation and it's business as usual...... except with the mixture screws cranked rich, the entire low speed circuit is a bit rich. To cover the tip-in sag usually the accelerator pump circuit is worked over, and then it all sorta works.
Part III
The proper way to set it up is to have the PCV be the idle air bypass and low-speed enleanment, then to set the Transfer slot exposure first with the mixture screws set in the middle of their range, and then leaving it alone while you set the idle speed with timing advance. Once the idle timing is fixed, then the power timing is fixed. and finally the rate(s) of advance are chosen between those two points.
Of course most of this has no effect on your hot-start.That is a Part I deal
Unfortunately I did not have a helper to put it in drive to adjust air fuel.
When in park my highest vacuum reading is with the air mixture screwed all the way in, this does not seem right to me almost like I have a vacuum leak. Both sides react the same. Current vacuum around 12 at idle and 15 ish air/fuel all the way in.Yeah this is not right, and covered in a previous comment. Cracking the secondaries is a vacuum leak, an internal vacuum leak. Primaries not set correctly on the transfer slot could also be an internal vacuum leak,but now with fuel added in an incorrect AFR.
OK with the additional pics, I see that you do not have a working PCV; get that fixed before anything else is attempted, because it affects everything except the power timing.
PS I love the color of your Dart.
And I could live with that shroud no problem, and for sure I would not install electrics to ditch it. I think it adds a tough-guy look to your underhood,lol.
And those valve covers are probably the best kind you could have. As already mentioned, check for interference between them and the aluminum intake runners. Most of the time these covers are used, they have to be notched at the runners to make room for them.
And now for the really big deal
Check your idle timing with and without your vacuum advance hooked up. I think you have your can hooked to full-time manifold vacuum. The Vcans are able to add from about 9 to 22 degrees at your 15* of idle vacuum. If you run it this way with 15* of initial, your total idle timing could end up being 24 to 37*, and the only way to slow the engine down would be to back out the speed screw......... which would kill the transfer port exposure.
Now riddle me this; if you shut off the transfers,With no PCV idle bypass air, what is the engine supposed to idle on? And how is it supposed to be able to hot-start?
When you get everything working again, you should be able to hot-start it with just a twist of the key; click-vroom.
So to recap
Install a PCV system,
Make sure your breather breathes in both directions.
Close up the secondaries.
Set the T-port exposure to square to a bit longer than wide.
Reset the mixture screws to 3/4 turn.
Replumb your Vcan to the spark-port.
Start it up and;
>Reset the idle-timing to 10degrees.
>Verify that the Sparkport has less than 4inches of vacuum on it at idle, preferably ZERO inches vacuum. And that the vacuum there rises with rpm.
>Fine tune the idle speed to about 700/750rpm, using a combination of speed screw adjustment in the range of +/- .5 turns from the initial T-port exposure setting, and the rest with idle-timing.
>Reset the idle quality with the mixture screws in the range of .5 to 1.5 turns from lightly seated.
> The idle fuel,(the mixture screws)and part throttle fuel ( the transfer ports), comprise the low-speed circuit, together with the float level adjustment and the Idle-Air-bleeds. When you dink around with the Idle-timing and try to maintain a proper idle speed, this messes up the low-speed fuel delivery system. With a 3000TC there is no reason to run a lot of initial timing. Get this sorted and then if you like you can whack the timing in with lightweight springs in the Distributor.
Setting the idle speed fuel is a balancing act between the mixture screws and the Transfer port exposure. In most cases, and like yours where the idle vacuum is quite high, having the mixture screws set to between .75 turn and 1.25 turns, and the exact right amount of transfer exposure, will yield the best idle, the best off idle and the best Tip-in response without a lot of help from the accelerator pump.Let the idle timing fall where ever it wants to; between 10 and about 18 degrees, to get an idle in the range of 700 to 750. At this stage I wouldn't bother with trying to maximize idle vacuum, or idle AFR, or Idle-timing; you cam mess with that at some later date, after you have a good-working base tune in her.
The mainjets will not affect this part of the tune; you could take 'em right out with no change in the idle. And as long as the PV is not ruptured, it will not affect the idle/low speed circuit either; you could block it right off without it affecting the idle/off-idle at all.
But the float level is a BIG,
BIG, player in this circuit. Saying it is good is somewhat vague. Saying it is set to the factory spec is the proper answer.
> forget about the vacuum gauge as an
idle speed tuning tool. You can however install it, and read it, and use it for a diagnostic tool, for all other purposes.
Happy HotRodding
