2000 RPM "Whislte"

[Tom L.]

Finally got the opportunity to take the vette for a ride to work today but once I got onto the highway and reached crusing speed, about 65 MPH (Lame I know), with the motor turning about 2000 RPM a slight whistle would come and go. Didn't sound like a belt and when it started an almost insignificant lift of the throttle, and no noticable change in RPM, made it go away. In contrast a smilar application of throttle made it return. Below 1800 RPM no whistle at all.

Any thouights?

BTW- '72 LS-5, auto if it matters.

[Joe C.]

Re: 2000 RPM "Whislte"

Finally got the opportunity to take the vette for a ride to work today but once I got onto the highway and reached crusing speed, about 65 MPH (Lame I know), with the motor turning about 2000 RPM a slight whistle would come and go. Didn't sound like a belt and when it started an almost insignificant lift of the throttle, and no noticable change in RPM, made it go away. In contrast a smilar application of throttle made it return. Below 1800 RPM no whistle at all.

Any thouights?

BTW- '72 LS-5, auto if it matters.

Not enough information.
Take the air cleaner off of the Quadrajunk and listen closely. Listen for a vacuum leak somewhere. It might also be alternator whine. Do you have a weak battery? It's not wind noise, right?
Also, you might need a friend to help by putting the car in gear, and throttling up to 2000 RPM with the e-brake on, wheels chocked, and assistant's foot hard on the brake.

[Tom L.]

Re: 2000 RPM "Whislte"

Just finished rebuilding the distributor, with positive results by the way, and re-timed it (without the air cleaner) only a few days ago...no whine apparrent when I checked total timing but that wasn't sustained for long. battery is fine, alternator is quiet and the only wind noise is from the side view mirror. If I put my hand next to it that noise goes away. I will try the power brake thing later, I hadn't thought of that. Thanks!

[Tom L.]

"whistle" update...

After the trip to work this morning I was lookig for something... well less than obvious. After some thought and a ride home with the tempermental "whistle" I checked the obvious. In the garage I ran the motor to 2000 and held it. Sure enough the "whisle" was comming from the belts. DARN-IT!!!

Long story short, I replaced the P/S and alternator brackets with "GM restoration" brackets. After installation things looked a lot better but not perfect but I still went with them. So I guess this is the source of the whistle. Has anyone had a problem with the alignment of the brackets? I re-checked the order of assembly with the AIM and it seems I have it correct.

Any help would be helpfully silencing. Thanks!