I have recently encountered an issue with my car, and I really can't think of anything that happened to cause this issue...it just started happing and I noticed it one day a few weeks ago. The car is a 71 Dart 225, supersix, 2.25" exhaust, Mopar electronic ignition, ~8.5CR, and the carb is a 1 year old (from new) Holley 2300 series 350CFM 2bbl.

The car has ran GREAT for the longest time (well over a year), but now it starts REALLY hard, cold or hot (30+ minutes after I turnoff the ignition). Before, in the mornings I would pull the choke out (manual) a ways, and the car would instantly start, then I would back-off the choke a little and drive. Now in the mornings the car turns over several times, I have to put the pedal to the floor, and finally after a few more cranks it fires and runs REALLY rough for about 10 seconds, and there's lots of smoke out the tailpipe which looks to be gas. This happens even with the choke all the way open, untouched.

The odd variable in this, is after this occurs, the car runs great. Drives great, idles great, accelerates great (no hesitation)...no problems other than this. The other issue is the car smells of gas really bad, even in the morning in my garage it just COMPLETELY smells of gas. Here are the things i've checked:

The choke isn't getting stuck, it's a manual choke.
The float isn't stuck, i've checked through the site plug...i've even adjusted it up/down and it makes absolutely no difference on the starting.
I took the bowl and metering block off the carb, cleaned the passages and needle/seat, replaced the gaskets, absolutely no difference.
The plugs look fine, maybe a little clean and a little sooty on the bottom, but they look the same as 2+ months ago when the car started perfect.
I run 10 degrees advanced timing
I've thoroughly checked for vacuum leaks on the carb and manifold several times, and I can't find anything, I read 20" of vacuum at idle.
I don't run anything off the manifold vacuum, and I even plugged the ported vacuum to the distributor for a couple days just to test, no difference.
I was thinking that maybe there's a lot of fuel vapor from the carb, so overnight I left the hood open and the air cleaner off and started it in the morning, no difference, started just as hard.
No cylinder is missing, they all seem to be turning great compression, and the valves are adjusted.
PCV system is working correctly as far as I can tell, I even threw in a new PCV valve that I had laying around (correct plastic type) in for a few days, and it made no difference.
I have done the fuel line mod and I use a new Wix metal fuel filter.
I've made a few carb adjustments such as leaning out the idle screws, adjusting back the accel. pump, lowering the float, JUST to test to see if it made a difference on the starting, and it didn't at all.

The only thing I can think is the warmer weather causing heat soak, but i'm a bit reserved on that---the car ran great last summer, and my carb is pretty well isolated with a thick BBD gasket > adapter plate > holley gasket. Like I said, i'm really confused because the only problem I can see is starting, anytime after 30 minutes or so being turned off, all the way until the next morning (12+ hours later).

Thanks in advance for any help, and I can provide more info if needed.

What happens if you try a cold start without using the choke? Does it start any faster or easier at all? Sounds like one way or another, a bunch of extra fuel is puddling in the intake manifold with extended sitting, causing the engine to start hard and run roughly until the extra fuel is cleared out. The sudden heavy smell of fuel in the garage also points this direction. A little baffling given that you've done the fuel line mod and your carb is well insulated, but I think the first thing I'd do is install a new inlet needle and seat. If this carb has a nonmetallic (nitrophyll) float, I'd also install a new one of those, and set it to the specified height. Some of today's fuel formulations are very aggressive to various fuel system components, including rubber and nitrophyll. A not-super-great inlet needle tip, together with a somewhat-heavy-because-soaked float, would allow a good-sealing fuel pump to overfill the carb on shutdown.

Another thing you may want to do to combat the tendency of hot weather to aggravate conditions like this is to install a vapour-return system. It uses a 3-nipple fuel filter; the 3rd is ¼" and has an 0.060" orifice to prevent bleeding off useful fuel pressure. You run a new vapour hose from that 3rd fitting all the way back to the fuel tank.

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

Dan,
To answer your question, no difference in starting with the choke all the way open (unused) or the choke half way closed.

The car has a brass float, but I will go ahead and order a new needle and seat.

Since my car is a '71 CA car, I have a fuel line that runs all they way up onto the fender, and connects to the breather on the valve cover. Is there any way (to save myself some work) that I could use that fuel line as a return line also? Like, could I just splice into it?

Ah, right, a '71. Next test: Remove the fuel cap from the car when you park it for the night. See if there's any change in startup behaviour the next morning.

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

65Dodge100,
I have checked intensively for fuel in the crankcase several times over the past week or 2, and can't find any trace of it, so I assume the fuel pump is fine.

Dan,
Test is completed! I parked the car last night and started it up about 12 hours later, the gas cap was off the entire time, no difference on starting.

Should I assume from your previous post, that this is indeed a problem with the needle/seat and to replace it, as welll as install a fuel pressure bleedoff system? If so, can I "T" into the fuel line that runs up onto the fender and connects to the breather on the valve cover? Lastly, does anyone have the WIX part number for the 3-fitting fuel filter?

Or are there more tests for me to try?

So the evaporative emission control system (fuel tank venting, and carburetor bowl venting if it's still tied in...where's the carb bowl vented?) is _probably_ okeh.
I would.
I'd do that, too.
That's kind of iffy. You don't want to be putting fuel into the crankcase. If you absolutely must do it this way, try and do it as far down (towards the ground) as possible. It's more of a nuisance to run the vapour return hose all the way back to the tank, but it's a better idea. You could tee into one of the four(!) lines that connect to the vapour storage pipe (which leans against the left rear wheelwell and can be seen by opening the trunk) — I'm pretty sure you'll find a piece of hose connecting each of the fuel tank's four corner vent nipples to each of the four lines running to the vapour storage pipe in the trunk.
Wix 33054 or NAPA Gold 3054, Purolator F20030

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

The fuel tank venting is installed correctly (to the breather on the valve cover)

The carb is new aftermarket, so it's a direct atmosphere vent straight up into the air cleaner housing. FYI I thought this might be part of the problem, but it doesn't seem so. I took the air cleaner off and left the hood open to see if the air cleaner was 'catching too many fumes' and causing part of the problem, but that didn't make a difference. I run a 'stock' Mopar 4bbl air cleaner, as it fits on my aftermarket holley 2bbl.

Thanks for the help, I will order a new needle/seat and install the fuel pressure bleedoff system and report back in a week or so once they're installed.

Have you pulled the carburetor completely off the manifold to make sure you don't have loose parts allowing fuel to leak directly into the manifold?

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Joshua

The '71 fuel tank vent is more complex than "to the breather on the valve cover". You will probably want to check and make sure the whole system is put together correctly: One tube from each corner of the fuel tank to the vapour storage pipe in the trunk, one tube from that pipe up to the engine bay and connecting to the crankcase breather, and (in your case) the vent nipple on the fuel pump body capped off securely.
There are two carb bowl vents. It sounds like you're talking about the internal vent here, which is a small pipe coming out of the inner sidewall of the carb throat and angling upward, with its open end facing the sky. The external bowl vent is the one I'm asking about. If it's not connected to the factory location (vent nipple on fuel pump body) then it needs to vent directly to atmosphere, not into the air cleaner housing or elsewhere.

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

Dan,
Where is the other external vent on a Holley 2300, 350 CFM 2 barrel?

Do you have a picture of this external vent?

I am going to try the same thing when I install the Weiand manifold.

Thanks,

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Aggressive Ted

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74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I have taken the carb completely off, removed the metering block and bowl, checked everything, cleaned it out, put it back together with new gaskets, checked for leaks (I don't even see any gas leaking down the throttle bores), and i've checked extensively for vacuum leaks, replaced the carb gasket, and nothing, exactly the same, absolutely no difference. Joshie225, do you have any suggestions on what else other than the basics I can check for? Any ideas of something I may have overlooked?
I wasn't as thorough in my speaking, but yes, everything is for sure connected correctly. I dropped and cleaned this fuel tank, cleaned it, and re-installed it following the FSM. (this was probably a year or 2 ago).
I checked through my Holley manual, and for the 2300 series 350CFM model #7448 I can only find 1 fuel vent, which is the stationary one. Also just as a reminder, this just all of a sudden started happing after the blue...the car has started GREAT for the longest time.

OK 1 more thing I found out......might be useful information.....
As per Dan's test, I started the car this morning with the gas cap off, and it made no difference (still started very hard and rich). The car ran/idled for maybe 1 minute max after being off all night, and I went back inside the house. For the heck of it, I went out about 1 hour later just to see if it would start hard after having just been 'ran cold' briefly, and sure enough, it started just as hard, no difference. It seems that this problem happens no matter what, not just after being driven for a while.

Red arrow points to external vent, green arrow points to internal vent. Maybe not all 2300s have the external vent (and sorry, I had the 2280 in mind when I talked about the angled internal vent...it's vertical on the 2300):

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

Yeah. Not too likely, but try a cold start with the PCV valve pulled out of the valve cover grommet and just lying there.

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

Quite alright, I will physically check the carb tomorrow and see, but i'm fairly sure it does not have an external vent.
Will do tomorrow morning, and I will post the results then.