After some hiccups, the 60 170 is running well at curb idle (around 750rpm, headlights on) and it's not overheating after finally getting the timing adjusted right. Hurrah!

There's only one other running issue that I'd like to solve and that's warmed-up re-starting.

The engine will now also re-start after running warmed up where it wasn't before. This is great and obviously had a lot to do with getting the timing right. But there's still some carb issue. It doesn't matter if it's 10 seconds after you kill the engine or 5 minutes. I'm always forced to crank the engine, and only after goosing the throttle slightly during cranking will it catch. Every time, the engine stumbles and runs rough while the exhaust ejects a nice cloud of black, unburnt-fuel exhaust before finally running smoothly again.

I've experienced this condition for years before I rebuilt the engine, but I just ignored it. Since I just rebuilt the carb with a Daytona kit and their new Daytona float valve (no needle & seat) I'm surprised this is still happening. I did verify to the best of my ability that the float level was set correctly in the bowl and follow the FSM carb rebuild procedures.

What else could be the problem? What section of the Fuel System "Troubleshooting" diagnosis could be the issue? Maybe "Poor Performance - Mixture too rich"? Something else? Under this section, they list:

1) Restricted Air Cleaner - checked that - this is good
2) Excessive Fuel Pump Pressure - don't know how to measure or adjust this but did just rebuild the fuel pump and it's providing a good and immediate flow of fuel whereas before the diaphragm had holes and leaks.
3) High float or fuel level - I checked the spec on this and float should be set correctly at 7/32" to float crown, inverted.
4) Damaged needle & seat - replaced with new Daytona float valve
5) Leaking float - I did not check this out - maybe a slow float leak could be the culprit?
6) Worn main metering jet - didn't check this - how can I visually inspect and tell it's worn? I haven't seen a rebuild kit yet come with a new main metering jet. Where would I obtain a replacement? Is the jet the same for all BBS series Carter carburetors 60+?
7) Sticking choke - choke is operating correctly and not sticking - verified

Thoughts?

Two thoughts:

After fully warmed up temperature shut down, during restart, the choke plate has to be fully retracted by choke stove's bi-metal spring. If plate is closing, or flopping around during a warm restart it needs to be adjusted. Adjustment is accomplished by bending choke stove rod to correct length, and or turning bi-metal spring to increase or lessen force that hold choke plate where it has to be depending on engine temperature; this can be a trade-off between cold start and hot restart tension and position of choke plate.

Also check to see if there is some dribbling of fuel down the carburetor directly after shut down that would cause fuel puddling on floor of intake manifold which would cause a temporary excessive rich condition and or a wet plug or two when engine sucked in the extra liquid fuel once started.

One more thing, be sure all rods and linkage between choke stove and choke plate are not binding, or sluggishly moving. Dirt, and or worn spots on these rods where they connect to their mate will often cause binding even if clean. If you find worn groves, using a fine mill file, carefully dress these groves so that they are smoothed enough to allow free movement when tension of stove spring is applied. Don't use any wet lubricant on these rods and their connection points as it will attract dust and grit, and in no time you will have sticky lazy moving choke linkage.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

#2 above. Black smoke out the exhaust means an intake full of fuel.
If it floods in '10 seconds' after being shut off, you will most likely see fuel dripping or running down the carb throat when you shut off the engine.

Too much fuel in the bowl? (you've addressed some obvious causes already)

Fuel boiling out of the bowl? (though it usually takes a bit longer after shutdown)

Siphon effect? Isn't there usually a small air bleed (on the booster?) to break the siphon?
If so, that could easily plug up with varnish or dirt.

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O==\=/==O

"A mechanic is Somebody."
- Jim Preston

This is happening. I see fuel bubbling out of a tiny port in the venturi and puddling on the throttle butterfly plate. What kind of correction is needed?

Fuel line mod and 3/8" thick carb-to-intake gasket.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan. I can do the 3/8" thick gasket but I really wanted to keep the stock appearance of the fuel hard line on this car because it's bent so nicely. Silliness I know! I suppose I might forgo the fuel hardline if there is no other way to solve this problem and retain a stock appearance. Do you suggest these fixes because the problem I'm experiencing indicates to you that fuel is boiling in the bowl and boiling over into the Venturi? Was this a common issue that people would just deal with by cranking and stomping on the gas until it started? Seems odd...

Then you'll have to cope with the consequences.
Yes, I am suggesting these fixes because they're fixes!
Seems odd if you're used to fuel-injected cars that start immediately no matter what.

Sorry, dude. I'm jetlagged and sleep deprived all to hell. I guess if you gotta-just-gotta-just-gotta have that hardline, you can disconnect it and leave it in place, doing nothing and going from nowhere to nowhere, and let the fuel flow through the setup described at Fuel line mod.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

In '60, did any of these cars come with a carburetor heat shield, either made of fiber, or other materials?

My car has a length of hard plastic wire loom that is split lengthways installed over the factory steel fuel line between fuel pump and carburetor. Yup, that black flexible stuff one sees all the time at the car show snaking around a lot of engine compartments. I have never had a problem with percolating fuel or hard starts when hot, even when temperature gauge swings full right from heat-soak after a brief shut-down on a hot day.

Perhaps you could try this method of insulating the fuel line, and if it works good, if it fails there is always SSD's fuel line mod.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

No. That didn't come along until 17 years later. Also the pre-mid-'63 hardline routing practically guaranteed the problem you're having. mid-'63-up routing made the problem less severe but didn't eliminate it. See here. The early cars have a very cramped engine bay and everything gets hotter, plus you have no choice but to burn 2014 gasoline instead of the 1960 variety; you'll have to deal with this reality.

PS: Real old cars that start up like "CHUN-ka-VROOM!" are way cooler than real old cars that refuse to start without gas pedal acrobatics and extended cranking and clouds of black smoke...even if the crankity-crankity-crankity-black-smoke car has a hard fuel line visible only when the hood's up.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It's obvious what replacing the steel hardline does in this swap, but what does using the thick 3/8" gasket accomplish that the thinner one doesn't?

Thick gasket material, for lack of better terminology, provides a higher R value than the thin one of same material resulting in less heat transfer between manifold and carburetor. A shiny metal heat shield reflects some unknown to me percentage of long inferred wave emanating from both exhaust & intake manifolds from bathing surface of carburetor as well as slowing heat convection via air; result is cooler carburetor.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

You also want to make sure that the "heat riser" valve on the exhaust manifold is in the fully open position when hot. If it's not fully open (or flops around loosely) it will heat up the intake more than normal- making your hot-soak problem worse. The thicker carb base gasket is recommended because it will reduce some of the heat transfer from the intake to the carb.

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63 Valiant Wagon
225 - 4 bbl

Got it. Last night I swapped out the thin carb gasket for the thick one and tried enshrouding the hard steel line with plastic covering (had some on hand) as suggested.

Nope, didn't do a thing. Lots of fuel still percolating and dribbling down the carb throat after shutoff. The placement of the horizontally-oriented fuel filter (directly over an exhaust manifold runner) has got to be the biggest issue. That, and I plan to adjust the fuel level in the bowl slightly to account for 2014 ethanol-blended gasoline, which I'm told may warrant a slightly lower level than the 1960 specs.

Doing the fuel line mod as well. Has worked great on the '63 Dart - no hot starting problems at all.

Only thing that somewhat sucks (no pun intended) about this is the vacuum advance pod on the 60 diz (I actually need to verify that it's working correctly) seems a little different than later models. It's got a hard plastic line running from it nearly all the way up to the carb and it was conveniently clipped to the steel fuel line in a very nice-looking way. With the fuel line mod, I'll have to just run it kinda loose from the pod to the carb vacuum port, or replace the pod entirely with a newer style one and a rubber line. Oh well.

Remove vacuum advance hardline. Take to parts store. Buy short length of brake line steel tube with thread fittings on ends same as the ones on dist advance line. Cut this brake pipe 1.5 inches from each end. This gives you two pipe stubs each with threaded fitting. Screw one into carb. Screw one into vacuum advance. Connect with rubber hose.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.