just started about a week ago.

302 in a 85 bronco. holley 600 cfm on a edlebrok performer intake. only 3 vacume hoses. distributor, PCV valve, and power assist for the breaks. all hoses new, new distributor, new PCV valve.

only happens under moderate acceleration. 2-3500 rpms. on the floor usually not there. nothing @ idle and runs smooth as a purrin kitten.

I heard that carbs can do this after getting broken in. is this true? everything has about 3-4k miles on it. except engine.,....that is about 18k

 

Have you checked for a vacuum leak at the intake manifold, put a vacuum gauge on it and see what it shows.
Jim

 

but doesn;t a vacume leak cause idleing problems? how much vacume should I have @ idle and driving down the road?

 

may be a bad water pump bearing. sometimes they will make noise. if the pumps not leaking and its not overheating keep driving.

 

 

Usually your vacuum at idle should be 17-21 inches, while running it all depends on the speed, going up hill, down hill, on a flat, your vacuum is going to vary. Yes, a vacuum leak will effect idle, the best way to find out if it is leaking is to test it with a gauge, you may have something that's causing the leak that's not evident at idle, maybe the linkage is twisting the carb. Hook up the gauge and start pulling on things, carb, hoses, pcv in correct direction etc.. and see if you can get the whistle at idle.

Jim

If you do have a whistle then it's an air leak, if it's a squeal then that's something else.

 

100% definate whistle!

been watchin the kids. no time to work on it. maybe tommarrow!

 

i had the same problem with a holley carb off a 69 or 70 440 dodge. i foung out that it was the air whistling underneath the throttle plates so i put it on a different intake manilfold and it went away. i thought it was the base gasket for the longest time but changing it a number of times didn;t help. you could try installing a riser plate maybe

 

there is already a riser plate there.

have yet to check vacume. since the tranny is about to fall out from under me. I can live with the whistle.

 

Did anyone ever resolve the issue in this thread?

I have a high pitched whistle or squeal in my 1961 F100 292 that starts at high speed, disappears under load or heavy acceleration at high speed, but returns once load is gone or cruising at 50-70 mph. The whistle or squeal never appears under idle conditions or low-speed city driving. Once the whistle/sqeal starts, it will go away after about 5 minutes at idle. It will start up again at highway speeds, and go away again if I idle for another 5 minutes. Thought it was the distributor, but it wasn't(just replaced the distributor). It's got a holly 2-barrel carb, there's only once vaccum hose (to distributor). Can't seem to find or feel leaks around carb or intake manifold, but it's got to be one of those two things, right? Other than a major annoyance, if it is a carb or intake manifold leak, does it really matter. The truck idles and runs pretty well, and gets about 12 mph.

 

could this whistle be caused by the riser plate/spacer. i have a 302/holley 4bbl/edelbrock intake and i get a similar whistling that only occurs at certain spots on throttle and pushing the throttle more or less makes it go away. ive heard of the spacers whistling before but idk what that whistle is supposed to be like

 

A long time ago, I installed a 70mm throttle body and EGR plate on my 1987 Mustang, but never got to do anything with the intake manifold. There is a definite lip at the EGR junction, as the intake opening is smaller than the EGR opening. It whistles under certain load conditions, and I can hear it because I also removed the intake silencer.

If you have any kind of ridge or gap at the junction between parts like the carburetor to spacer, or spacer to manifold, where the holes are not exactly aligned, it can make noise under the right flow conditions.

 

ok that makes sense, illl have to tear it apart next time im home and check for a lip