1978 hissing sound after valve cover swap

[Brandom Havener]

hello guys/gals!... I am new to this forum but not new to the owning of the Thunderbird. I have owned it for 4 years now and done work to it multiple times before. i just did a valve cover swap and have run into an issue. when i did my swap i put my hand into one area and heard what sounded like a "relief of pressure /hissing noise" now mind you i've done this 3 different times and have not had the issue. needless to say i finished the swap and am done. i have done a complete tune up as far as "new spark plugs, wires, distributor cap and rotor, distributor, fuel filter, air filter, oil, etc. the list goes on". i have no misfires and none of that jazz. my issue is i will start my car and its fresh after the start. i can push on the gas pedal and everything works fine. the second i let off the pedal it idles for maybe 3 seconds, then sputters, then dies. this was not an issue until i did this recent valve cover swap. i have reason to beleive it is a vacume line issue. what i"m basically asking y'all is " what do you beleive could be the issue?, if it is as i suspect then how do i isolate the issue, and does anyone have any vacume diagrams for this car?" or any diagrams for anything for this vehicle specifically?another note is after a week and a half the headlight covers just kinda popped up without being turned on. I apologize for my grammar guys/gals. Any help is appriciated. -BraHa

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[tbird]

hello guys/gals!... I am new to this forum

Please read your welcome message before your next post.

Your subject should be a summary of what your post is about, not the make, model and trim level of your car. Also, we are an all Ford Thunderbird site, so no need to include Ford Thunderbird in your subject.

Your subject "1978 Ford Thunderbird heritage edition /351 modified" has been revised to 1978 hissing sound after valve cover swap.

 

[74 Harley]

Well I have done a lot of vacuum line replacement in older Fords, you probably have a line that is broken/ rotted at the vacuum tree behind the carburetor. Normally what I do is buy 15 to 20 feet of vacuum line in each size and do a trace/ replace. One at a time until they are all done. You may not need that much, but I find it convenient to keep on hand.