Cold carburetor?

[Anonymous]

Hi guys, I was wondering if carburetors are usually cold and stay that way the whole time the engine is on. I know this is a weird question but I was trying to see if there was a leak around the gasket on the bottom of the carburetor, so I sprayed some carb cleaner and noticed that the engine stalls. I also sprayed some butane and same thing happened. The enigine stalls no matter what part of the carburetor I spray. I was told that if the spray is flammable, the engine will race, but if it is non-flammable it will stop. I am not so sure if the carburetor is supposed to do that but it makes sense that it stays cold if it is vacuum. By the way, it is cold, not cool. Thanks.

 

[Mercury Mike]

I don't understand the question... but... if you spray carb cleaner around the carb, as long as it's not getting sprayed inside of it, the idle shouldn't change unless there's a vaccuum leak.

 

[Anonymous]

Hi, sorry if I confused you. The thing is that I have sprayed carb cleaner and butane around the base of the carb and the engine tries to stop. I read that if there are no leaks that the engine should stay the same. Mine stalls when I spray around the base or anywhere on the carb. I replaced both gaskets three times already and it still does it. Even if I don't spray around the base but directly on the carb, for example on top of the HOLLEY markings, on the front of the carb etc., it will stop completely. I was wondering if this is normal or if there is something wrong with the carb. Thanks again. Hopefully this explains a little more.

 

[Mercury Mike]

That's not normal. If you're giving really quick bursts, then it should speed up a little with a leak. If you're giving it generous sprays, just like a generous spray directly into the carb, the car will stall for a second. Anyways... You've got a bad leak somewhere. Where is sylmar, CA? I can stop by sometime this week if you'd like and take a look at it. It's about an hour and 15 minutes from my house. Lunch on you? =P

 

[xctasy]

Awesome, dude!

There are a raft of little emissions, vaccum, electrical and gasket fittings which can cause this. You're car isn't UFO afflicted, and Keep spraying in moderation until you see what mechanism above is the guilty party. Then tell us, and we'll give you some ideas as to what you can do.

A non extensive list of items and terms bellow:-

On some Holleys, there is an idle stop solenoid, an electric choke, a couple of vents for the carb jets found in the top air horn. On some 350 cfm Holleys, there is an external vent on the float bowl, and a dashpot which dampens movement of the throttle. Some major pipes found at the base and near the base of the carb are Ported Vac, Maniflod vac, Postive Crankcase vent, they can do really wierd things if the pipes are cracked and have oil sitting in them.

Basically, anything on a vent or leaking emissions pipe can stop an engine.

 

[Anonymous]

Thanks guys! Sorry for the delayed reply. I had no chance to use the internet. I appreciate all of the replies. I have checked but no I don't seem to have a leak around the carburetor. I have checked with my vacuum gauge and I get a reading of 16inches but it constantly jumps back and forth quickly from 16-17inches. My timing is at 10degrees and the idle speed is running at 475rpm as per the manual on a 170cid fordomatic. I read somewhere that the valve guides might need to be replaced. I checked the valve lash and they are ok but it still has a roughness at idle. Thanks 65Stang200, I have little time to work on it and only during the night, about 1-2 hours from 10pm-12am, but if I get a chance I would really appreciate it. Thanks guys.

 

[Anonymous]

is that the idle speed in drive or nuetral? because you should be setting it in drive and that vaccum seems a little low for a stock engine, I would try turning the idle speed up and maybe try upping the timing too?

 

[ludwig]

You should be pulling a minimum of 18 lbs. and it shouldn't jump around. Your timing mark may have slipped on the membrane and you don't have it timed to absolute spec. You may have a fuel/air mix thing going on, like a bit too lean.
Put the car in drive and set the idle with the dwell tach. Use the vacuum guage to check the fuel mix. Screw the fuel mix screw down until it starts to quit, then back off to max vacuum and leave it there. Regardless of where your timing mark is on the outer ring, use the vacuum guage and time it for max vacuum, then look at where the mark really is with your timing light.
Now you can fool with some other stuff, like checking all those items Herr Ekstase listed.
I thought you used WD40 to check for leaks. Spray and if it levels out or speeds up you have a leak. I could be wrong though.