BB Engines w/Braided Ignition Wires

[Peter G.]

Why do Big Block engines on Corvettes require metal braided ignition wires and small block Corvette engines do not?

In some cases small block engines rev higher possibly creating a high pitch wine in the radio interference than BB?

[Terry M.]

Re: BB Engines w/Braided Ignition Wires

Why do Big Block engines on Corvettes require metal braided ignition wires and small block Corvette engines do not?

In some cases small block engines rev higher possibly creating a high pitch wine in the radio interference than BB?

But small blocks do have ignition shielding -- or at least they did when they left St Louis. Those of us who own them can testify to what a PITA all that sheet metal shielding is. The need for shielding has nothing to do with how high the engine will rev, and has more to do with the car traveling next to you than with your radio.

Both small blocks and large motors have distributor shielding and in most cases that shielding is nearly identical.

[Robert K.]

Re: BB Engines w/Braided Ignition Wires

Terry,

Can you offer a little explanation of your words "more to do with the car traveling next to you than with your radio" in your above post........ What are you referring to?

Thanks,

[William C.]

Re: BB Engines w/Braided Ignition Wires

OK. TVRS printing on the secondary ignition wiring is short for "Television Radio Suppression" If you are old enough to remember the early '50's you will remember that the TV would do the "heebie Jeebies" when some cars came down the street, that was due to the RF interference given off by the sparkplug voltages being sent down from the distributor to the plugs. This was somewhat minimized by the metal body in normal cars, but all manufacturers by the mid 50's used some sort of suppression in the secondary wiring. When Corvette was introduced, the fiberglass body did not provide the second level of shielding to be compliant with federal regulations so the secondary shielding in the form of metal covers was added. On a bigblock, due to the location of the plugs this was not possible, so the individual wires were shielded and grounded, again to meet FEDERAL requirements to allow the radio to function in the car next to you in traffic or at a stoplight.

[Joe L.]

Re: BB Engines w/Braided Ignition Wires

But small blocks do have ignition shielding -- or at least they did when they left St Louis. Those of us who own them can testify to what a PITA all that sheet metal shielding is. The need for shielding has nothing to do with how high the engine will rev, and has more to do with the car traveling next to you than with your radio.

Both small blocks and large motors have distributor shielding and in most cases that shielding is nearly identical.

Terry and Peter----

The cylinder head and exhaust manifold configuration of big blocks did not lend itself to the type of radio interference shielding used on small blocks. So, the designers had to come up with something that would provide equivalent function in a different manner. Thus, the externally braided ignition wires were born. I'll bet it was a lot cheaper than the small block shielding, too. Most small block guys probably wish the braided wires had been used for them instead of the sheet metal pieces.

Also, I believe that the radio interference shielding was primarily installed to reduce radio interference for the Corvette rather than other cars. If not, it would have been installed on all Corvettes and not just those equipped with radios. The carbon core spark plug wires may have been more directed at radio interference in surrounding cars, though.

[Terry M.]

Re: BB Engines w/Braided Ignition Wires

Terry and Peter----

The cylinder head and exhaust manifold configuration of big blocks did not lend itself to the type of radio interference shielding used on small blocks. So, the designers had to come up with something that would provide equivalent function in a different manner. Thus, the externally braided ignition wires were born. I'll bet it was a lot cheaper than the small block shielding, too. Most small block guys probably wish the braided wires had been used for them instead of the sheet metal pieces.

Also, I believe that the radio interference shielding was primarily installed to reduce radio interference for the Corvette rather than other cars. If not, it would have been installed on all Corvettes and not just those equipped with radios. The carbon core spark plug wires may have been more directed at radio interference in surrounding cars, though.

Amen to the nuisance and aggravation of the sheet metal shielding on small blocks. Every time I changed spark plugs or wires my cut hands bothered me for weeks afterwards. The many small blocks without that shielding is testimony to that aggravation.

Interesting point about the lack of shielding on the no radio cars. My thought had always been like Bill's that the shielding was more for the car next to you, or the television in the home you were driving by. But Bill is talking about the carbon core wires, which ALL Corvettes, radio or not, received. So maybe the wires are for the RF suppression for others and the shielding for the radio in the Corvette.

[William C.]

Re: BB Engines w/Braided Ignition Wires

You are correct, the metal firewall in cars does wonders for the built-in radio in the pass car, but is a feature Corvettes lacked. The TVRS wires protected the neighbors TV and nearby radios.

[Peter G.]

Re: BB Engines w/Braided Ignition Wires

Thanks to everyone who responded. This question came up to me after reading another post here on the TDB about braided wires for BBs. I figured their had to be a difference between the two engines that nesscessitated the different wires and now I know.

So from the postings here if a SB owner was having some interfearance on his or her radio, then they could buy braided wires and have all the bases covered? The problem would be the vendors may not make in sizing wire sets in braided for SB because of very low demand?

[William C.]

Re: BB Engines w/Braided Ignition Wires

The oem manufacturer (my former employer) never made a braided smallblock set, as they were not needed with the factory installed installation. If you have noise, first best to isolate the source, check for all the proper caps installed on the Voltage regulator, various switches and such. Is the noise engine speed related? if so, what wires are you using, otherwise, trace to the source. Alternator noise can also vary with speed...

[Robert K.]

Re: BB Engines w/Braided Ignition Wires

Hi Terry,

Yes, I'm quite sure that that is what they were for, i.e. " wires are for the RF suppression for others and the shielding for the radio in the Corvette". Driving a corvette past a house in the neighborhood and causing interference with a TV would perhaps have been pretty small considering the amount of time spent driving by, the number of corvettes in a neighborhood, etc. I don't think GM would have invested big $'s in that, do you?

[Terry M.]

Re: BB Engines w/Braided Ignition Wires

Hi Terry,

Yes, I'm quite sure that that is what they were for, i.e. " wires are for the RF suppression for others and the shielding for the radio in the Corvette". Driving a corvette past a house in the neighborhood and causing interference with a TV would perhaps have been pretty small considering the amount of time spent driving by, the number of corvettes in a neighborhood, etc. I don't think GM would have invested big $'s in that, do you?

Actually I do because the Federal Government made them and other car manufacturers -- even and especially back into the 1950s. Now days with digital TV signals and solid state electronics radio interference is not so much an issue, but back when TVs has vacuum tubes it was. If you read the fine print on the back of almost any appliance, including modern radios and TVs, and the papers that come with your cell phone, there is a statement to the effect that it meets FCC requirements for noise suppression. That is the standard auto manufacturers had to meet as well. As Bill said, metal cars were not so much an issue, but plastic cars were.

[William C.]

Re: BB Engines w/Braided Ignition Wires

As Terry said FEDERAL regulation, and they did check!

[Dick W.]

Re: BB Engines w/Braided Ignition Wires

Why do Big Block engines on Corvettes require metal braided ignition wires and small block Corvette engines do not?

In some cases small block engines rev higher possibly creating a high pitch wine in the radio interference than BB?

The high pitched whine is more often the alternator. Ignition is usually a popping sound, especially at idle. T******* the antenna on the older cars actually helped a little, at least on the stronger stations.

RF can cause strange things to happen. Very early on we ran ABS tests (late 1960's early '70'), two way radios would trigger the system to release the brakes Trucks were required to have ABS in 1974, a lot of scrambling by manufacturer's and fleets to make it work.

Another thing that I used to have fun with was the early fuel infested VW's. The CB radio fad was at it's peak and my radio was slightly modified, 500+ watts. Could pull up behind or beside one of those Rabbit's, key the microphone and whistle keenly. Guaranteed to kill the engine on that little bugger We won't go into public address system's TV's etc.

[John H.]

Re: BB Engines w/Braided Ignition Wires

Another thing that I used to have fun with was the early fuel infested VW's. The CB radio fad was at it's peak and my radio was slightly modified, 500+ watts. Could pull up behind or beside one of those Rabbit's, key the microphone and whistle keenly. Guaranteed to kill the engine on that little bugger

Dick -

Back in the mid-70's when CB was everywhere, I had one in my daily driver with a switchable 100-watt linear amplifier, and I could kill a VW Squareback (1st-generation Bosch fuel injection) if it was within 30-40 feet just by flipping the linear on and keying the mike; could also illuminate a flourescent tube by holding it within a foot of the antenna and keying the mike with the linear on.

You can imagine what my home base rig did to the neighbors' TV reception (tube-type Browning Golden Eagle SSB, D-104 modulated mike, 300-watt water-cooled tube-type linear, 25-foot tower on the roof, rotor, and Moonrakers). Hardly ever used the linear with the home base except for emergency drills, but it did "get out" with the switch on.