[archerytony]

Seems to be a common thing but I havnt seen what works to cure it. I have a 66 cutlass frame off restored new grounds on everything and then some, MSD street fighter and pro billit with exterior coil ignition , later internal reg alt, I have a older craig AM/FM tape player with a 45 watt 4 way alpine amp I just installed. It buzzes when its running and its fine when its not. Seems like its coming from the alt if I turn up the volume it drowns it out and it goes along with the engine revving. I do not have a elec fuel pump in case someone is wondering. I have heard the condenser on the coil does not work with msd? Any help out there?
Thanks for any help
Tony

[Kokamo]

Remove the alt belt and start the motor to confirm the alternator is in fact the problem. If it is still there without the alt spinning, then you have an ignition issue.

Do you have resistor plugs?

~Joe

[Pepi]

Originally Posted by Kokamo

Remove the alt belt and start the motor to confirm the alternator is in fact the problem.

I have heard when diodes go bad the alternator can cause that.

[archerytony]

Originally Posted by Kokamo

Remove the alt belt and start the motor to confirm the alternator is in fact the problem. If it is still there without the alt spinning, then you have an ignition issue.

Do you have resistor plugs?

~Joe

I will try that and check on my plugs too and let you guys know. The Alt is new

[68lemansman]

Bad ground somewhere?

[rohrt]

You are correct that it a common problem.

Standard tolerance on a alternator should not exceed 1 volt peak to peak on the output. However you would need an O-scope to measure that. Your radio should be filtering any motorboat whine as long as its not exsesive.

First you should isolate if the radio output is making the noise or if it just when the amp is connected. One common issue is a groun loop. Where the ground at the radio is different then the ground of the amp. May want to experiment with a ground strap connecting the radio chassie to the amp.

One thing you could check out is a DC to DC converter to filter the power.

I'm sure some the car stero guys have more experience in this then I do.

[george kujanski]

The grounds on the radio, amp, and ignition should be connected as close as possible to the battery negative. Connecting these grounds together thru sheet metal causes the noise to mix into the power feeds. The amp especially should get it's own ground return back to the battery neg.

george

[archerytony]

Originally Posted by george kujanski

The grounds on the radio, amp, and ignition should be connected as close as possible to the battery negative. Connecting these grounds together thru sheet metal causes the noise to mix into the power feeds. The amp especially should get it's own ground return back to the battery neg.

george

will do

[rexs73gto]

If you find out that the noise is there when the alt. is connected or not connected it's an old trick but you can put a cheap conderser on the power side of the alt output & that usually takes care of any buzzing noise as it absorbes it at the sourse also you may want to check to make sure you put the hood ground back on the car when you took it apart. The hood ground is the sharp pointed item usually in the middle of the hood mounted on the cowl so when you close the hood it comes in contact with the hood when closed. Some take them off when the car is painted because they think it will scratch the paint on the hood but it needs to be there to take care of the problem your talking about.

[archerytony]

Originally Posted by rexs73gto

If you find out that the noise is there when the alt. is connected or not connected it's an old trick but you can put a cheap conderser on the power side of the alt output & that usually takes care of any buzzing noise as it absorbes it at the sourse also you may want to check to make sure you put the hood ground back on the car when you took it apart. The hood ground is the sharp pointed item usually in the middle of the hood mounted on the cowl so when you close the hood it comes in contact with the hood when closed. Some take them off when the car is painted because they think it will scratch the paint on the hood but it needs to be there to take care of the problem your talking about.

Well last night I had the alt belt off and it still does it so I think its the msd doing it. never knew about the hood ground Im sure mine is long gone but I do remember what you are talking about. I am going to try running the wires direct to the bat and see what it does. It is a cheap stereo but with the amp it sounds good when the motor is off. Theres not much room in my garage so I have to wait till it stops raining to try this stuff outside
Thanks Guys I will let you know what happens

[2002Z4CSS]

Originally Posted by archerytony

Seems to be a common thing but I havnt seen what works to cure it. I have a 66 cutlass frame off restored new grounds on everything and then some, MSD street fighter and pro billit with exterior coil ignition , later internal reg alt, I have a older craig AM/FM tape player with a 45 watt 4 way alpine amp I just installed. It buzzes when its running and its fine when its not. Seems like its coming from the alt if I turn up the volume it drowns it out and it goes along with the engine revving. I do not have a elec fuel pump in case someone is wondering. I have heard the condenser on the coil does not work with msd? Any help out there?
Thanks for any help
Tony

I would get a noise filter and install it on radio power feed circuit. Maybe even one on the alternator too.

[archerytony]

Originally Posted by archerytony

Well last night I had the alt belt off and it still does it so I think its the msd doing it. never knew about the hood ground Im sure mine is long gone but I do remember what you are talking about. I am going to try running the wires direct to the bat and see what it does. It is a cheap stereo but with the amp it sounds good when the motor is off. Theres not much room in my garage so I have to wait till it stops raining to try this stuff outside
Thanks Guys I will let you know what happens

Well I hooked the ground up direct to the batt it helped but still some noise I ran the hot to the batt then too and it helped a little more than tryed it to the power tabs on the fuse panel it was about the same but at least it turns off with the key. Most of the noise is gone but is still there on low volume I am going to look up a filter and see if that will finish it.

[HWYSTR455]

A ground from the amp case directly to the chassis of the head unit will do it, as mentioned in post #6, went through this just recently. It doesn't have to be a large gauge wire either, 18g will do it. Some RCA leads even have the ground built into them.

.