Engine dies when cold?

[rms427]

My 427 side-oiler will not stay running when cold unless I keep the rpm above 1,500-2,000. After a few minutes it runs fine and idles at 800 to 900 rpm. This started a while ago after several years with no problem. I thought it was caused by old gas but I ran down to 1/4 tank and filled it back up and still have the problem. I have not run a choke on the car and have a 800 cfm holley double pumper and 6al ignition. Any ideas what is causing the problem?

[patrickt]

Originally Posted by rms427

Any ideas what is causing the problem?

Air bleeds -- clean them out in less than three minutes and then you, too, will refer to me as GGTM. Do a search on here for "God's Gift to Motorsports" or click here:
This is new: stumbling/missing at idle/cruise speed

or here:

Heavy, over-rich upon starting. Why?

or here for my long drawn out detailed post on it with pics, etc:
Holley Carb Woes - DCDoug Pay Attention (Long Post)

[DougD]

I'm not sure how cold you consider cold, but I'm from Iowa, also running no choke, and I'd say it was acting normally.

[rms427]

Cold is a relative term. I guess I should have said before the engine warms up for several minutes. Ambient cold here in California lately is 60-95 degrees. I have run the car without the choke in the past when the ambient temperature was near 32 degrees without this problem. I tried the carb cleaner and it seemed a bit better but it still died before it ran for several minutes unless I kept the rpm at about 1400. I will try more carb cleaner to see if it corrects the problem. Today may not have been the best test since the ambient temperature is almost 100 degrees. I may have to hook up the choke but it's funny I hadn't needed it for years and thousands of miles.

[patrickt]

And you're actually shooting it down the eight air bleeds themselves, not just the throat of the carbs, right? If it's really clogged, then you might have to remove the idle mixture screws and squirt the cleaner in there as well. But first really blast out the air bleeds. The passages go all the way down so really use the cleaner in there.

[ERA Chas]

Forget the bleed crap and DON'T remove mixture screws. If bleeds are gunked, they're gunked hot or cold. This clown has an electric choke on a p**** motor.
It's the temp in the chambers that has to come up before the mixture burns evenly. The whole head, piston top and plugs need time to get to stable temp. Ask how I know.

[patrickt]

Chas, can't you be nice? But I would like a correction from the OP -- is this a recent problem that has come about or has it always been this way or are you not sure?

[decooney]

Originally Posted by rms427

I may have to hook up the choke but it's funny I hadn't needed it for years and thousands of miles.

Hey Ray,
is this the same carb we had apart at the Cobra Bash in 2005 in the front Peppermill parking lot by chance? If so and it did not do this before, my guess is it would be worth removing carb, taking it apart, using a full can of carb cleaner on it, and have a set of gaskets ready for it. Also, checking to make sure your fuel filter is not clogged while its apart. When these things sit with 15% ethanol blend coming out of CA gas pumps these days its a wonder we all don't have more problems with our carbs. I bet it just time to clean it out a little bit, and to make sure the needle/seat is not stuck closed on the floats, etc.

[rms427]

It's the same carb. Most likely it's just gunked up since I hadn't driven the car for some time before the problem occurred. However, I have left the car much longer without having this problem in the past. It's strange that it runs fine once it's warmed up. I would expect if something is clogged it would affect the engine even when warm.

[Chaplin]

I think you just need to let it warm up. Every carbureted engine I own, from lawn tractor to motorcycle to Cobra, will not idle without a choke when cold. Pretty normal. If it did idle well when cold without a choke, then I'd be worried something was wrong.

[Leecbr]

Patrickt,

Thanks for the post on cleaning the air bleeds..I had back spray when I first sprayed the carb cleaner into them. They were pretty dirty. When I sprayed them the second time with carb cleaner it went straight in...it's amazing the difference now. My car idles like a brand new car.

Chaplin is right, In the colder months/temps my cobra had a hard time starting...I had to install a manual choke. It use to take about 5 tries if I was lucky to get the cobra to start. Once I added the choke, it starts the first time everytime. I pull the choke half way out and follow with one full pump on the gas pedal...When I turn the key, it fires up no problem. Then I feather it in to where it will idle and not die. Then when it's warm, I push the choke all the way in...Done..Off I go.