my bud just put a 460 in his 79 so he can be like me lol and he has a rebuilt edelbrock that whistles i assume this is just a slightly leaking diaphragm what do you fellas think? i know when the 460 had a Holley on it it didn't but as soon as he put edelbrock on it it made better power but has a loud screaming whistle thats annoying as hell

 

That's a vacuum leak. Make sure the two small ports on the front are capped if they're not in use; and make sure the port in the back has a pipe plug installed if it's not in use. Make sure the carburetor is bolted down properly and evenly with a proper gasket in between.

The accelerator pump diaphragm is not exposed to vacuum and has nothing to do with the problem.

 

still whistles and it has new vacuum lines all around and plugged correctly its bolted down correctly the only thing i see thats a little funky is the line going to brake booster is a little questionable and the whistling is right by the carb

 

You'll have to look for vacuum leaks by leaning out the idle mixture so that the truck barely runs, then spraying around suspect areas with a can of carburetor cleaner and listening for a jump in idle speed. If everything were plugged and bolted down correctly, you wouldn't have this problem - therefore you'll need to find it with this test.

 

we tried that yesterday that was the first thing we did after double checking vac lines and carb gasket and tightness

 

All I can say is check more, and go through everything again. If there truly were no vacuum leaks, then you wouldn't have a vacuum leak. The sound you hear is air being sucked through a small opening at high velocity.

 

thats kinda what i figured but we will keep lookin

 

Have ya checked the brake booster and booster line? Maybe a fan belt slipping?

 

smoken ever figure it out, my truck is doing the same exact thing and i have too checked any and all vacuum lines, interested in knowing if you figured it out

 

yea we figured it out it was the spacer under the edelbrock carb was narrower than the mating surface of the carb by only a razors width we bought a new phenolic spacer and it solved the issue

 

well i have a holley 2bbl on top of an adapter plate going to my 4bbl intake, what kind of gasket should i buy to put under the adapter? i need to get rid of this noise

 

if you have a 4bbl to 2bbl adapter you use a 4bbl gasket underneath and a 2bbl gasket between top and the underside of the carb.... i like using a 4bbl intake with a 2bbl carb i always seem to get better gas mileage with that set up...... if worst comes to worst i guess you could probably use rtv silicone i personally don't use it unless i have to

 

yeah i realize that, but i mean if i got o the parts store what kind of gasket do i tell them i need, a 4bbl phenolic spacer?

 

if you explain to them what the gasket is for they will probably know (in other words i don't know whats its called other than a gasket for a phenolic spacer or a 4bbl to 2bbl adapter gasket)

 

alright bud thanks, ill let ya know if it works!! thanks