Changed Dustributor, Now Radio Static
Thread Starter
Racer
Joined: May 2013
Posts: 357
Likes: 15
From: Marshville, NC
Changed Dustributor, Now Radio Static
Good Friday evening all, I have a 78 vette with basically stock engine and 350 turbo auto. I changed out the tired factory HEI distributor today with another one. New CFR 65K HEI Distributor.
The swap took just a few minutes and the car runs great. Now the radio picks up ignition noise. I can hear every cylinder fire through my speakers, leave the ignition on and cut off the motor and all is good.
I changed nothing but pull and replace the distributors.
Sure would like to listen to the radio again, any suggestions?
The swap took just a few minutes and the car runs great. Now the radio picks up ignition noise. I can hear every cylinder fire through my speakers, leave the ignition on and cut off the motor and all is good.
I changed nothing but pull and replace the distributors.
Sure would like to listen to the radio again, any suggestions?
Burning Brakes
Joined: Oct 2007
Posts: 1,086
Likes: 22
From: Crystal Lake IL
St. Jude Donor '12-'13
do you have one of these...pic compliments of Willcox
http://repairs.willcoxcorvette.com/w...stallation.pdf
http://repairs.willcoxcorvette.com/w...stallation.pdf
Thread Starter
Racer
Joined: May 2013
Posts: 357
Likes: 15
From: Marshville, NC
do you have one of these...pic compliments of Willcox
http://repairs.willcoxcorvette.com/w...stallation.pdf
http://repairs.willcoxcorvette.com/w...stallation.pdf
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Tach filter has nothing to do with radio noise. It prevents voltage spikes from being read on the tach as additional RPM.
For limiting ignition noise, the plug wires should be resisance wire type; there should be some metal (or mylar) shrouding around the distributor area and that shrouding must be electrically grounded. On earlier C3's (points type), the ignition coil had a filter capacitor attached with it. Not sure what 78's had in that regard.
For limiting ignition noise, the plug wires should be resisance wire type; there should be some metal (or mylar) shrouding around the distributor area and that shrouding must be electrically grounded. On earlier C3's (points type), the ignition coil had a filter capacitor attached with it. Not sure what 78's had in that regard.
Last edited by 7T1vette; May 13, 2016 at 11:54 PM.
Thread Starter
Racer
Joined: May 2013
Posts: 357
Likes: 15
From: Marshville, NC
Tach filter has nothing to do with radio noise. It prevents voltage spikes from being read on the tach as additional RPM.
For limiting ignition noise, the plug wires should be resisance wire type; there should be some metal (or mylar) shrouding around the distributor area and that shrouding must be electrically grounded. On earlier C3's (points type), the ignition coil had a filter capacitor attached with it. Not sure what 78's had in that regard.
For limiting ignition noise, the plug wires should be resisance wire type; there should be some metal (or mylar) shrouding around the distributor area and that shrouding must be electrically grounded. On earlier C3's (points type), the ignition coil had a filter capacitor attached with it. Not sure what 78's had in that regard.
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
Check grounds for the antenna coax, radio antenna and wires.
Before you swap the coil, make sure the screws for the new coil are tight. Look at the rotor button and other parts too.
Before you swap the coil, make sure the screws for the new coil are tight. Look at the rotor button and other parts too.
Last edited by mikem350; May 14, 2016 at 06:16 AM.
Thread Starter
Racer
Joined: May 2013
Posts: 357
Likes: 15
From: Marshville, NC
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
That may be where your problem is located.
Also, the grounding path for the distributor is actually from the dist. body, to the dist. clamp, through the hold-down bolt and then into the engine block. If all that stuff is painted up, you won't get a decent ground to the distributor and ignition system. It may run OK, but that might cause the noise in the electrical circuit.
Another thought: Where is the radio power wire routed? For least noise, you want it to go directly to the battery (through a fuse, of course) or as close to the battery as possible. There is no better 'noise' filter than a big battery.
Last edited by 7T1vette; May 14, 2016 at 04:13 PM.
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
All good advice above.