I have a 1979 F-150, with the stock 2-bb carb(2150 model) and 351M engine. The carb was replace with a rebuilt one about year ago. The truck performs well. The only problem is after the driving around town, the truck develops a whistle on deceleration then stops after the truck stops and is at idle. The truck will also whistle, after it has warmed up, while in park. The whistle does not happen on acceleration. At first I thought it was a vacuum leak, I was unable to find one in the cab(A/C lines). I opened the hood and the noise was got louder and sound like it is coming from the carb. The noise is annoying and I was wonder if anybody else has had or heard about this problem.

 

You have described a vacuum leak. get the spray carb cleaner and start spraying around the base of the carb, hose connections, with engine running. you will notice a difference in idle when you find a vacuum leak.


Wayne 60 F-350
e-mail
https://www.ford-trucks.com/users/whomrig

 

I had a whistle from the carb that was caused by the wrong gasket under it. Air was passing from the front 2 to the rear 2 and whistling doing it.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.

 

I had the same problem not long ago. Turned out to be the vaccume line to the brake booster. Check the hose and the grommet in the booster.

Nathan

 

I have a 1978 F-150 with a 351M/C6 and I had a whistling noise comming from my 2 barrel carb. It was the outlet from the choke. That is, it seems there is a threaded fitting on the choke for a thermal "Wand" that would have attached to the exhaust manifold. The "Wand" was missing and the carb was whistling.
Good Luck

 

Thanks for the tips. I found the vacuum leak. I hosed the base of the carb down with carb cleaner and found the leak near the choke. I tighten up the choke housing and whistle stopped. Thanks again.
Warren