Cold weather driveablility problems

[max]

This summer I installed a Weber 38 with electric choke on my 1980 Mustang with a 200 six automatic. It ran great until the weather cooled off in the late fall, about 40 to 50 degrees F.
When it comes off the choke it stumbles and bogs for about 15 minutes. My mechanic says that because there is no warm air whatsoever heating the carb during warm up, it will run rough after the choke comes off till it is fully warm. He pointed out that tall Clifford carb adapter is actually still very cool even after a 25 minute run into the City, so I suspect he is correct. There is really not much to adjust on this carb.
He suggested reinstalling the warm air intake tube that runs up from the exhaust manifold, to an original air cleaner housing from a Pinto or Pinto based Mustang, as apparently they also used a 2 barrel Weber. My air cleaner is an open type, no warm air preheat at all, at any time. My original carb was the single barrel 1946 Holley so that air cleaner housing won't work.
Any others with this experience, or any advice regarding the air cleaner switch? Any other Fords that had a 2 barrel with a stock air cleaner that might fit the Weber?
Thanks.

 

[fordconvert]

He could be right since you have changed so many things. I have several engines running in cold weather without those tubes and such but they still have stock intakes and carbs to that may be just enough heat to keep em going.

 

[JackFish]

Yes a Fairmont/Zephyr with a 4cyl, or an early fox body with a 2.3 carbed engine.
I have two, they came with the carbs I found at the j-yard! 8)
Although I'm not sure they would be an exact fit for your particular carb.

 

[Harte3]

Those adapters look tall enough to fabricate piping/hose around them and splice in to a heater hose :

 

[max]

Thanks Guys, much appreciated. I will see if I can find a housing locally, there is a Ford wrecker who also specializes in turbo charging 2.3 liter. non turbo Fords, he may have a spare housing.
Otherwise I may try the fabrication route, although it is a bit chilly to be fiddling around out there right now.
Nothing like the weather you are experiencing in Winnipeg though Jackfish.

 

[Harte3]

Our Canadian brethren are sharing .

http://www.wunderground.com/cgi-bin/fin ... ct=WEATHER

2*F for a high tomorrow...I don't even want to work in the garage .

 

[STEVEN.]

Ha! You guy'z think that's cold,that's funny . ~OO6.

 

[falcon fanatic]

Hmmm, my weber 38 is installed with no heating and a plain open element k&n filter and it has been working great this winter. It was 20* one day last week and I drove it, no problems. I think you have a tuning problem. Perhaps you should start by resetting the lean-best-idle-adjustment, and then make sure you have enough advance at idle.

http://www.webercarburetors.com/ppw/htm ... unning.htm

 

[falcon fanatic]

it may be that your idle jet are a little too lean in the cold air. cold air=higher density which requires more fuel. If the lean best idle adjustment doesn't work, try stepping your idle jets up one size. You should be able to tell if you have too small idle jets as lean best idle will require too many turns to adjust propoerly.

 

[66 Fastback]

My Weber has an electric choke and it ran poorly when cold. I timed how long it took to open the choke and if I recall it was only a couple of minutes for it to go to full open. Of course by then the engine was not warmed up. So I wired in a couple of resistors to step down the voltage going to the electric choke so that it would take a bit longer to open. I think I may have gotten it up to 7 minutes or so. I did this several years back. In the summer, I pull the resistors off since I do not need them then.

You might take a look and just see how fast the electric choke is openning with a stone cold engine. I think the warmed air intake would help. Another alternative would be to hook up the heated carb spacer. On occasion, I think I have had some carb icing issues when the temp and humidity were just right. I don't recall having those problems when I had the stock carb and carb spacer.
Doug

 

[fordconvert]

If you are going the resistor route for most people the easiest high watt resistors to get are the old ballast resistors from an auto parts store. Most come in a nice ceramic body with nice big terminals on them. I believe the mopar ones may even have 2 taps for different resistances.

 

[max]

Thanks for the tips. I had a look at the choke a while back. I watched it open just to make sure it worked. I didn't time the choke, but it seemed to open in a LOT less then 7 minutes, so the short choke time could be part of the problem.
I also have it running on the lean side. I will make some adjustments and see how it works.
Might throw in a bit more advance too.

 

[66 Fastback]

I used some resistors from Radio Shack and they are a bit small. I should probably use the larger ballast resistors. The 7 minutes is not as long as I would like to have it, but at least it let me get on down the road a couple of miles and start putting some heat into the system before the choke openned up fully.
Doug

 

[BUZZ]

When you remove the aircleaner do you see any condensation in the carb above the throttleblades?

I've been fighting a similar problem for about a year and a half now with a Holley 2300. The main problem I'm having is condensation. The humidity always stays high in Mississippi and when ever the temp hits about 40 or lower I can remove my aircleaner and there will be waterdrops everywhere. You can even see condensation on the outside fuelbowl.

 

[gearhead138]

it may be that your idle jet are a little too lean in the cold air. cold air=higher density which requires more fuel. If the lean best idle adjustment doesn't work, try stepping your idle jets up one size. You should be able to tell if you have too small idle jets as lean best idle will require too many turns to adjust propoerly.

I agree.
I had the same problem with my weber in cold weather. I had a tall, custom fabricated intake adapter that I thought was the problem. I added heater hose connection to the intake and no change, but when I added bigger idle jets it cured it totally.

 

[max]

I will have a look for condensation if it ever stops snowing long enough, and gets above 10 degrees!!!
Also, I have the PCV hooked up to the barb, seems to work fine, but I seem to recall that some folks recommended against it. The suggestion was to just run a hose out of the PCV hole and leave it open.
Any connection between this and the poor cold weather running?

 

[gearhead138]

I think you need to put in larger idle jets. I believe the weber 38 comes with 45 idle jets stock. They are easy to replace, you can access them from the side of the carb (no disassembly required). How far out is your idle mixture screw? They say if you have to turn it out more than 1 1/2 turns to get it to run smooth, then you need larger idle jets.

 

[max]

I checked both idle mixture screws, both were about 1 to one and a quarter turns out.
I tweaked the choke a bit, adjusted the spring by turning the plastic cover to hopefully get it to stay on a bit longer.
Also rigged up a hose running from the exhaust manifold collector back to the front of the air filter, so it should get some warm air as the manifold warms up.
Will see how this works.

 

[gearhead138]

Hmmm, my weber 38 is installed with no heating and a plain open element k&n filter and it has been working great this winter. It was 20* one day last week and I drove it, no problems. I think you have a tuning problem. Perhaps you should start by resetting the lean-best-idle-adjustment, and then make sure you have enough advance at idle.

What size idle jets are you running in your carb?

 

[max]

Just an update, I enriched both mixture screws as suggested, both are still within the limits posted in one of the replies.
I added a bit more advance, not sure how much as my timing light is shot, but it isn't knocking so I guess I have some more room there too.
I also checked the automatic choke to ensure it was working. It was, but I loosened the 3 screws that hold the plastic cover that covers the bimetal coil that opens the choke, and rotated it counter clockwise a bit. That made the choke stay on longer, and it idled on its own till it was warmed up.
Then for some reason it quit as it came off the cold to warm idle. Started right up though, off the choke, and idled fine, ran fine too. It had fully warmed up by then.
So, perhaps all three things made the difference, but I suspect the choke adjustment made the most difference.
What I will do tomorrow is drive it with the choke on and see how it runs with only a minute of warming up. It is about 40 degrees F these days.
And Vann, no condensation noticed in the carb, outside temp was around 40 degrees.