Ignition SHeilding Question?
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Ignition SHeilding Question?
I've seen photos of a shield around the distributor on some vettes. Was this standard equiptment on all vettes or just some? My 79 doesnt have it, should it? What was the purpose of this? Did it help suppress eleectrical noise ? DId the fiberglass bodies on vettes cause havoc with radios etc? Right now I'm getting interference with my digital gauges and was thinking this might be the culprit. Is this item still available? Can I fab one out of something?
Thx Again as ALways,, ESU
Thx Again as ALways,, ESU
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
any of the older models - C1's, C2's, and early C3's all had chrome distributor shields IF the car had a radio in it. If it was a radio delete car it didn't have the shield installed at the factory.
The shield was to help prevent ignition interference with the radio since the fiberglass firewall was useless for that purpose unlike a standard metal car body.
At some point (not sure of the year) the later C3's switched to a plastic or fiberglass material distributor cover. This material is useless for shielding the interference so inside is a layer of foil to act as the shielding.
Your '79 should have the cover unless it was specifically ordered without a radio. Chances are a previous owner or mechanic working on the car took it off and never reinstalled it. You should be able to find a replacement at the parts vendors.If you can't find it at the parts vendors, look at places like Corvette salvage yards such as Contemporary Corvettes in Bristol Pa.
I'd need to double check my '78 AIM, but I think there is also suppose to be a ground strap from the cover to the block
The shield was to help prevent ignition interference with the radio since the fiberglass firewall was useless for that purpose unlike a standard metal car body.
At some point (not sure of the year) the later C3's switched to a plastic or fiberglass material distributor cover. This material is useless for shielding the interference so inside is a layer of foil to act as the shielding.
Your '79 should have the cover unless it was specifically ordered without a radio. Chances are a previous owner or mechanic working on the car took it off and never reinstalled it. You should be able to find a replacement at the parts vendors.If you can't find it at the parts vendors, look at places like Corvette salvage yards such as Contemporary Corvettes in Bristol Pa.
I'd need to double check my '78 AIM, but I think there is also suppose to be a ground strap from the cover to the block
Last edited by BarryK; Sep 16, 2006 at 08:37 PM.
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Originally Posted by BarryK
any of the older models - C1's, C2's, and early C3's all had chrome distributor shields IF the car had a radio in it. If it was a radio delete car it didn't have the shield installed at the factory.
The shield was to help prevent ignition interference with the radio since the fiberglass firewall was useless for that purpose unlike a standard metal car body.
At some point (not sure of the year) the later C3's switched to a plastic or fiberglass material distributor cover. This material is useless for shielding the interference so inside is a layer of foil to act as the shielding.
Your '79 should have the cover unless it was specifically ordered without a radio. Chances are a previous owner or mechanic working on the car took it off and never reinstalled it. You should be able to find a replacement at the parts vendors.If you can't find it at the parts vendors, look at places like Corvette salvage yards such as Contemporary Corvettes in Bristol Pa.
I'd need to double check my '78 AIM, but I think there is also suppose to be a ground strap from the cover to the block
The shield was to help prevent ignition interference with the radio since the fiberglass firewall was useless for that purpose unlike a standard metal car body.
At some point (not sure of the year) the later C3's switched to a plastic or fiberglass material distributor cover. This material is useless for shielding the interference so inside is a layer of foil to act as the shielding.
Your '79 should have the cover unless it was specifically ordered without a radio. Chances are a previous owner or mechanic working on the car took it off and never reinstalled it. You should be able to find a replacement at the parts vendors.If you can't find it at the parts vendors, look at places like Corvette salvage yards such as Contemporary Corvettes in Bristol Pa.
I'd need to double check my '78 AIM, but I think there is also suppose to be a ground strap from the cover to the block
ESU
Burning Brakes
Joined: Jul 2006
Posts: 888
Likes: 1
From: North Texas
I don't want to hijack this thread, but I have a question in line with the subject. On the factory ignition shields for the early C3, were they chrome plated & polished or merely chromed? I have a 72 vert with a base 350 and what I think may be an aftermarket replacement. I believe this because the top piece, although chromed, is rather rough looking (appears to be poor quality plating). I'm really just trying to confirm my suspicion.
My thinking is that GM would have put a smooth chrome finish on the ignition shield, similar to the chrome air cleaner covers. Does anyone have experience with this?
My thinking is that GM would have put a smooth chrome finish on the ignition shield, similar to the chrome air cleaner covers. Does anyone have experience with this?
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Looking to pick one up for my 79, would rather have a chrome one instead of black plastic. when looking at the vendors catalogs none of them show a complete photo, just the individual parts. Hard to get an idea of what it should look like. Anyone have a photo or could possibly take a photo so I have an idea what to get?? Like I said, it's playin havoc with my digital gauges and I want to fix it. Can I fab something somehow, tin or aluminum??
ESU
ESU
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by BarryK
I'd need to double check my '78 AIM, but I think there is also suppose to be a ground strap from the cover to the block
If you recall I had commented on why there was a braided strap screwed into a plastic cover, then you informed me that there was a foil material underneath the cover.
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Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by Bob Onit
There is Barry
If you recall I had commented on why there was a braided strap screwed into a plastic cover, then you informed me that there was a foil material underneath the cover.
If you recall I had commented on why there was a braided strap screwed into a plastic cover, then you informed me that there was a foil material underneath the cover.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by ESU
Looking to pick one up for my 79, would rather have a chrome one instead of black plastic. when looking at the vendors catalogs none of them show a complete photo, just the individual parts. Hard to get an idea of what it should look like. Anyone have a photo or could possibly take a photo so I have an idea what to get?? Like I said, it's playin havoc with my digital gauges and I want to fix it. Can I fab something somehow, tin or aluminum??
ESU
ESU
Maybe if you got a complete unit from an earlier year including the correct brackets it might work but I have no idea.
The plastic ones even have a molded in area where it fits around the tranny dipstick on auto trans cars.
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Originally Posted by BarryK
don't know how you would get a chrome unit on there unless you fabricated something up yourself out of sheet metal and had it chromed. The chrome units from the earlier years were completely different shaped than the plastic units your car originally came with.
Maybe if you got a complete unit from an earlier year including the correct brackets it might work but I have no idea.
The plastic ones even have a molded in area where it fits around the tranny dipstick on auto trans cars.
Maybe if you got a complete unit from an earlier year including the correct brackets it might work but I have no idea.
The plastic ones even have a molded in area where it fits around the tranny dipstick on auto trans cars.
ESU
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
ESU
no, all the shieldinhg was different for early '68-70, 70-74, 75-77, '78-82. That's just the small block motors. The BB motors also had different shielding.
All the shielding up thru 77 was chrome. From 78-82 it was the plastic shielding.
all of the different versions are shaped differently, require different brackets, etc.
none of them are simply "round". They all extend a bit on both sides of the distributor to cover as much of the ignition wires coming up from the sides of the motor as possible to block the interference.
The older styles especially are much more rectangular.
starting in '78 with the plastic version is was more curved and rounded because of the easier molding of the plastic as opposed to the previous metal versions.
i did a quick check at a number of vendors, Dr. Rebuild, Paragon, Volunteer Vette, and Mid America and no one seems to carry the '78-82 shield. It's listed as not available so you will probably have to find one on eBay or at one of the corvette salvage places like Contemporary Corvette or Pacific Corvette
http://www.contemporarycorvette.com/
http://www.pacvette.com/wa/
no, all the shieldinhg was different for early '68-70, 70-74, 75-77, '78-82. That's just the small block motors. The BB motors also had different shielding.
All the shielding up thru 77 was chrome. From 78-82 it was the plastic shielding.
all of the different versions are shaped differently, require different brackets, etc.
none of them are simply "round". They all extend a bit on both sides of the distributor to cover as much of the ignition wires coming up from the sides of the motor as possible to block the interference.
The older styles especially are much more rectangular.
starting in '78 with the plastic version is was more curved and rounded because of the easier molding of the plastic as opposed to the previous metal versions.
i did a quick check at a number of vendors, Dr. Rebuild, Paragon, Volunteer Vette, and Mid America and no one seems to carry the '78-82 shield. It's listed as not available so you will probably have to find one on eBay or at one of the corvette salvage places like Contemporary Corvette or Pacific Corvette
http://www.contemporarycorvette.com/
http://www.pacvette.com/wa/
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by ESU
I've seen photos of a shield around the distributor on some vettes. Was this standard equiptment on all vettes or just some? My 79 doesnt have it, should it? What was the purpose of this? Did it help suppress eleectrical noise ? DId the fiberglass bodies on vettes cause havoc with radios etc? Right now I'm getting interference with my digital gauges and was thinking this might be the culprit. Is this item still available? Can I fab one out of something?
Thx Again as ALways,, ESU
Thx Again as ALways,, ESU
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
This is the 1979 plastic shield. The inner surface is lined with tinfoil. The ground strap is held on by the wingnut on the right. The other end of the strap has a loop end and is fastened to the upper rear valve cover bolt. Unlike earlier metal/chrome shields held on by fasteners, it is simply a press fit. There is a lip on the front that slips under the air cleaner lid.
I haven't looked for one for many years but I understand they are not in reproduction. So a salvage yard or the parts section here may be your source. I doubt, however, that the lack of a shield is the reason for your gauge problems. I drove my 1979 without the shield installed for some time and there was no effect. As well it is removed for tune-ups and the gauges are not affected at that time. You may have a dash circuit board ground problem.
I haven't looked for one for many years but I understand they are not in reproduction. So a salvage yard or the parts section here may be your source. I doubt, however, that the lack of a shield is the reason for your gauge problems. I drove my 1979 without the shield installed for some time and there was no effect. As well it is removed for tune-ups and the gauges are not affected at that time. You may have a dash circuit board ground problem.
Last edited by Paul L; Sep 18, 2006 at 12:06 PM.
Racer
Joined: Nov 2000
Posts: 290
Likes: 0
From: Omaha, NE
I'm with Paul67(79) on this. Mine has been off more than it is on and doesn't affect my gauges or anything else-except appearance. I would hazard a guess that the 1977 shielding might come closest to working but check for air cleaner clearance differences. Good luck.
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Originally Posted by jackson
Are your plug wires a good quality set with Spiral or Helical wound core? ... and in good condition? Typically, those negate need for radiation shield. Or, a chromed steel shield setup for 75 thru 77 sbc C3 should fit 79 sbc C3 w/ GM large coil-in-cap HEI distributor.
ESU
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Originally Posted by paul67
This is the 1979 plastic shield. The inner surface is lined with tinfoil. The ground strap is held on by the wingnut on the right. The other end of the strap has a loop end and is fastened to the upper rear valve cover bolt. Unlike earlier metal/chrome shields held on by fasteners, it is simply a press fit. There is a lip on the front that slips under the air cleaner lid.
I haven't looked for one for many years but I understand they are not in reproduction. So a salvage yard or the parts section here may be your source. I doubt, however, that the lack of a shield is the reason for your gauge problems. I drove my 1979 without the shield installed for some time and there was no effect. As well it is removed for tune-ups and the gauges are not affected at that time. You may have a dash circuit board ground problem.
I haven't looked for one for many years but I understand they are not in reproduction. So a salvage yard or the parts section here may be your source. I doubt, however, that the lack of a shield is the reason for your gauge problems. I drove my 1979 without the shield installed for some time and there was no effect. As well it is removed for tune-ups and the gauges are not affected at that time. You may have a dash circuit board ground problem.
thx for the photos. I'm running digital gauges not analog. I was told by the manufacturer of the gauges there could be a problem and to use the shielded wire in the kit but alas my kit didnt come with it so not thinking there would be aproblem I wired them up without it. Needless to say they are mailing me the new wire now. The center gauges are not affected, just the speedo and tach which work off electrical impulses.
You're correct these are not available as repros, there is a guy out there who has the one you show , blk plastic, for $99.00. Dont know if thats worth it. Will probably wait till the shielded cable gets here, re-wire the gauges and see what happens. Would still prefer the chrome one , my engine compartment has a fair amount of chrome and anodized stuff.
ESU
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by BarryK
that's jogging my memory a bit - that was a while back wasn't it!!
Post #'s 34 and 35 and 36
http://forums.corvetteforum.com/show...ighlight=strap
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Originally Posted by paul67
ESU,
That's a ridiculous price. Pass. As I alluded to earlier, that shield really does nothing.
That's a ridiculous price. Pass. As I alluded to earlier, that shield really does nothing.
ESU