I don't think that it is really hurting anything, but on cool mornings as of late, when i start my truck up and leave, i have a whistle that sounds just like a turbo that is coming from under the hood, i am guessing that there may be a small leak between the carb, is this right? it is really high pitched when i am off the throttle, and the more gas i give it the deeper the pitch until it dissapears.

 

If your truck is running the same I kinda doubt it would be a carb leak, especially if it's not running lean/rich. No ideas what it could be at the time, except maybe the pcv valve, will post if I think of anything.

 

i currently have a similar whistle coming from my engine...when i find it, i will let you know where mine came from...

MontanaFord

 

Check for leaks in vacuum hoses, a tiny hole or crack in a hose or fitting can make that type of sound, same for gaskets around PCV valves and oil filler caps. Would also be worse at idle when you've got good vacuum. A cheap mechanics stethoscope can be handy at finding the not so obvious leaks

 

Easy way to find extrange noises...

Using a hose 1/4" to 1/2" and 3 Ft long, just put one end at your ear and point other end to engine and move aroud carb, vacum hoses, solenoides, etc...

It can be use also to fing bearing noise, lifter noise, rod noise, etc...

 

whatever it is, is it hurting anything? and if it is a vaccum leak i would i be noticing any performance differnces? When i get some free time other than at night i am gonna try your suggestions.

 

if the leak is small it can just be an annoyance noise wise, if its big you'll feel a performance hit. The vacuum leak does two things: #1 it thins the air/fuel mixture making you run a bit lean, and #2 it reduces the vacuum signal to whatever the vacuum line is going to. If it happens to be a line feeding your distributor's vacuum advance or a tranny's modulator valve the performance hit is a double whammy. If it's one of those many emission related thingys you'll probably not be able to tell a lot of difference assuming it's not a big leak.

Computer controled EFI motors are much more sensitive to such things, a tiny leak can make some vehicles all but undrivable.