Radio Interference any ideas?
Thread Starter
Pro
Joined: May 2001
Posts: 524
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From: watchung N.J.
Radio Interference any ideas?
We have a 1970 vette, the alternator, wires, plugs, are radio supression, I installed a HEI ignition as well, but when we turn the radio on we hear a crackling noise like sparkplugs firing but it is intermittent, and also at low volume we hear a electric noise that does't increase with engine rpms, I tried disconnecting the hot lead to the alternater but it still made the noise, I also replaced the capacitor in the distributor but no help. We d'ont have any of the ignition shielding, could that make the difference? is this stuff just for show?
and if not how come all other G.M. vehicles d'ont come with it and have no radio interference problems? or is this just another of those "vette" things?
Thanks SPOKE-
and if not how come all other G.M. vehicles d'ont come with it and have no radio interference problems? or is this just another of those "vette" things?
Thanks SPOKE-
Team Owner
Joined: May 2001
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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St. Jude Donor '06-'10, '13
Re: Radio Interference any ideas? (spokewrench)
I have a 1980 with HEI and NO ignition shielding. I don't have any electrical noise.
Two things to look at.
1. Radio wiring -- make sure you have a GOOD ground and that all the speaker wires are in good shape.
2. Swap with another radio to make sure it is not the radio itself.
Two things to look at.
1. Radio wiring -- make sure you have a GOOD ground and that all the speaker wires are in good shape.
2. Swap with another radio to make sure it is not the radio itself.
Melting Slicks
Joined: Apr 2001
Posts: 2,280
Likes: 0
From: colorado springs CO
Re: Radio Interference any ideas? (BSeery)
ill second what bseery says..
i also have a 76 with HEI with an accel high volt coil thingy and i sold the shielding a long time ago since it was a major PITA to change plugs....(got headers now...they go over the top :) )
i dont have any interference at all.
i should say that im using a sony CD deck (i cut the dash....)
check yer antenna grounding strap??
i also have a 76 with HEI with an accel high volt coil thingy and i sold the shielding a long time ago since it was a major PITA to change plugs....(got headers now...they go over the top :) )
i dont have any interference at all.
i should say that im using a sony CD deck (i cut the dash....)
check yer antenna grounding strap??
Racer
Joined: Dec 1999
Posts: 485
Likes: 0
From: MESA, AZ, USA
Re: Radio Interference any ideas? (spokewrench)
I have the same problem right now and will follow this thread.
One of the differences between Vettes and "other" cars is the fiberglass body while all others have the steel bodys shielding the engine from the radio. But I was glad to hear that someone has it working even without the shields. I really didn't want to put them in my "make-believe L88". I'll look at some of the items mentioned so far.
Thanks,
Andy
One of the differences between Vettes and "other" cars is the fiberglass body while all others have the steel bodys shielding the engine from the radio. But I was glad to hear that someone has it working even without the shields. I really didn't want to put them in my "make-believe L88". I'll look at some of the items mentioned so far.
Thanks,
Andy
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Re: Radio Interference any ideas? (spokewrench)
Noise also in my 71 but a whining noise tht does change with rpm. I've grounded head unit to ground, to battery, to antenna ground with no change. I've also used a powerlead filter and a capacitor on the pos lead from alternator.
Any other ideas?
Any other ideas?
Le Mans Master
Joined: Feb 2001
Posts: 7,226
Likes: 399
From: Northern CA
Re: Radio Interference any ideas? (spokewrench)
Here's another one to think about... I have perfect FM reception on the original AM\FM radio... but AM is so crackly with the engine on that's is nearly unusable. I've checked and rechecked ground straps. All are solid. Also have multiple filters on the components and even one on the hot lead to the radio. Still can't stop that static on AM! :cry
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Re: Radio Interference any ideas? (lou)
spoke-
The newer radios have better technology that is not as susceptible to RFI (radio frequency interference) as the older units. I have both a 66 and a 70 that were originally designed with shielding. New vs old = apples & oranges.
The 66 has the following:
Pioneer SuperTuner 3 Radio (newer technology)
Factory side shielding
Missing the top shielding
No stainless plug shields (not used in 66)
The 70 has the following:
Pioneer SuperTuner 3 Radio (newer technology)
Factory stainless GROUNDED plug wire shielding
Missing the top shielding
Both systems and antennas are properly grounded and all capacitors are installed where required and are within the correct capacitance range. (I have a capacitance checker).
The 66 has noticeable RFI.
The 70 does also, but it is almost imperceptible.
So, it seems that the stainless shielded wires have a noticeable effect.
If you have the original radio, then you may need to retain (or re-install) the shielding.
If you have a newer aftermarket radio, then GROUNDED shielded wires may help.
Just another 1 cent.
Edit: Since WATTAC had already mentioned it, I figured it was unnecessary to mention the fiberglass vs steel issue. This is the main difference between other GM cars and the early Vettes.
[Modified by Tom454, 8:31 AM 11/6/2001]
The newer radios have better technology that is not as susceptible to RFI (radio frequency interference) as the older units. I have both a 66 and a 70 that were originally designed with shielding. New vs old = apples & oranges.
The 66 has the following:
Pioneer SuperTuner 3 Radio (newer technology)
Factory side shielding
Missing the top shielding
No stainless plug shields (not used in 66)
The 70 has the following:
Pioneer SuperTuner 3 Radio (newer technology)
Factory stainless GROUNDED plug wire shielding
Missing the top shielding
Both systems and antennas are properly grounded and all capacitors are installed where required and are within the correct capacitance range. (I have a capacitance checker).
The 66 has noticeable RFI.
The 70 does also, but it is almost imperceptible.
So, it seems that the stainless shielded wires have a noticeable effect.
If you have the original radio, then you may need to retain (or re-install) the shielding.
If you have a newer aftermarket radio, then GROUNDED shielded wires may help.
Just another 1 cent.
Edit: Since WATTAC had already mentioned it, I figured it was unnecessary to mention the fiberglass vs steel issue. This is the main difference between other GM cars and the early Vettes.
[Modified by Tom454, 8:31 AM 11/6/2001]
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Drifting
Joined: Mar 2001
Posts: 1,411
Likes: 2
From: St. Louis, Missouri
Re: Radio Interference any ideas? (spokewrench)
"d'ont have any of the ignition shielding, could that make the difference? is this stuff just for show?
and if not how come all other G.M. vehicles d'ont come with it and have no radio interference problems? or is this just another of those "vette" things?"
That's due to the fact that none of the other cars manufactured by GM are made of fiberglass. A car built with a metal firewall, hood and fenders will provide much of its own shielding. A Corvette doesn't, which is why GM placed that shielding around the distributor. You may want to try to replace it.
and if not how come all other G.M. vehicles d'ont come with it and have no radio interference problems? or is this just another of those "vette" things?"
That's due to the fact that none of the other cars manufactured by GM are made of fiberglass. A car built with a metal firewall, hood and fenders will provide much of its own shielding. A Corvette doesn't, which is why GM placed that shielding around the distributor. You may want to try to replace it.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Re: Radio Interference any ideas? (Neo Fender)
That's due to the fact that none of the other cars manufactured by GM are made of fiberglass. A car built with a metal firewall, hood and fenders will provide much of its own shielding. A Corvette doesn't, which is why GM placed that shielding around the distributor. You may want to try to replace it.
Sometimes have a radio- currently no radio, no heater. This is not my area however you might find these comments interesting.
For FM- forget AM- spiral core wires should work w/o all the shielding w/ modern radios.
Had some noise on the original 8tk which I eliminated by cutting the interior light power wire.
Had some alt. noise as Will describes at one time. No help from filters. Ran all radio & amps. power directly from battery. (Did not use the filters.)
:cool:
