Jump to content

Fuel boiling in Weber 32/36


Recommended Posts

Driving the 74 620 on a test run yesterday and after about 15 miles it started starving for fuel. It would only idle a bit and when I’d press the gas it would die.  I’d let it sit for 5 min, restart it and it would rev up, but I’d only make it a few hundred feet then it would spit and sputter then die. I can hear a boiling sound coming from the carb. It’s like the fuel is boiling down in there.  After letting it sit for 30 mins to cool off I restarted it and it ran a lot better so I could get home. Timing seems to be spot on and I’ve never changed it from where it was with the stock carb.  I let it sit a couple hours...fired it up and it ran like normal. It’s full of gas so I know I’m not crazy.  I’ve had this happen on a Ford 2bbl and had to put a 1/4” spacer to isolate the heat so it could get to the carb. Anyone else have this issue?

 

thanks,

 

Andy

Link to comment
  • Replies 1
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

1/ I don't think it's near hot enough for vapor lock. Is the engine over heating? what does the gauge say?

 

 

2/ Have you replaced your fuel filter recently or ever???

 

 

 

3/ Was it near zero and damp? snow on the ground, freezing rain or foggy???

 

What you probably have is carburetor icing. This is because the Weber carburetor does not have the stock air cleaner and the ATC (automatic temp. control) This is a pipe from the exhaust to the snorkel on the air filter housing. There is a vacuum operated gate that mixes hot and cold outside air to regulate it near 100F so that even in the winter the engine thinks it's summer.

 

What's happening is it near freezing and when gas is mixed with the air in the carburetor it absorbs heat in order to vaporize. (wet your hand and blow on it.... it gets cooler) This lowers the air temp below freezing and the carburetor parts inside and often the bottom of the carburetor body are like the inside of your freezer and any humidity in the air forms frost. This will build up to the point the venturi stops working. You push the gas harder and harder and the vehicle slows down and stops. Often just sitting for a few moments the engine warmth melts the frost, it restarts and drives away... only to do this again within a block or two. 

 

What others have done is cut the bottom out of the air cleaner and replaced it with a steel sheet cut to fit the Weber. If you have your original air cleaner. You will also need the insulated pipe (duct AKA 'stove pipe') to the exhaust manifold and the manifold should have the sheet metal covering to collect the warmed air from.

 

I did cut up a metal coffee can and wired it to the exhaust. You can but the metalized 'stove pipe' from auto supply stores. You will need a proper air filter housing with a snorkel though.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.