Hi, I have a 74 f250 with a 67 352 and a 2150 carb. I have noticed that after driving the truck for a while and when its nice and hot, if I shut it off I hear a funny "howling" noise coming from the carb. It does it for about 5 seconds, then goes away. I rebuilt the carb and it still makes the noise. Also when I am driving it, when I have the pedal at a certain point, I can hear a lot of vacuum, I have checked for vacuum leaks, and there are none. The other question I have is, the 352 was out of a standard shift truck, mine is an auto, so I have no where to hook my tranny kickdown rod to. Does anyone have any ideas on how I can fix that, besides replacing the carb? Thanks, Jack

 

Hi Jack, the kickdown linkage connection on a 2150 is part of the throttle linkage. There's a mechanism that sits on the throttle shaft and rests right along with the attachment for the throttle linkage. The kickdown slips over a stud on the linkage and is secured with a clip. I'm not sure if the kickdown mechanism can be removed off a carburetor that went in a vehicle with an auto trans, or if it's pressed on to the throttle linkage. If no one else chimes in I'll try to go out in the shop and pull one. If the only way to remove the linkage would be to take the entire throttle shaft with it, I'd be hesitant to do so beacuse you'd have to remove the throttle plates to get the shaft out, which is a bad idea. The screws holding the throttle plates to the shaft are peened so that they won't work their way out, and you'd have to do something similar to re-install them which can be tricky.

I'd bet money that the vacuum leak you hear while driving, and the howling noise are related. It's probably the same leak. What we know so far is that it howls after you shut it off, which to me says it's coming from a place that would normally hold vacuum while the engine is off, but in your case it's escaping. That narrows it down - it rules out any kind of intake manifold leak. Are you sure it's not coming from the brake booster?

 

My buddys 302 converted Ranger had a howling noise at shut down, it WAS the brake booster vac. connection.

 

That is an excellent point FMC, I think the noise could be coming from the booster. I know the booster does have that loud "hush" noise when I depress the pedal quickly, which I am pretty sure indicates that the booster is on its way out. I will have to listen a little closer tomorrow and see if I can pinpoint that noise a little better. Thanks, for the input.