Which Spark Plugs

[Larry T.]

Sorry in advance. I know this has been addressed before, and I have searched the archives, but just can not find the answer I am looking for.

My car is a 1966 427/425. Of course it has TI. I have heard that I should not use a resistor type plug. Is that correct in all cases? If so what plug do I use (temperature aside).

If I were to use a resistor type plug what components are in jeopardy of being damaged?

Thanks in advance for any help.

[Jim T.]

Re: Which Spark Plugs

Larry check the "Similiar threads" at the bottom of your post and you should be able to get the information you need. If you had a SB I would say use Champion R12, I like the extended tip plugs.

[R N.]

Re: Which Spark Plugs

R45XLS (25 ft/lbs torque) GM # 5613878 is the advise I took from others here for my "66 L72 and they work fine.

[Larry T.]

Re: Which Spark Plugs

So what is the story regarding damage to the system by using a resistor type plug?

[Clem Z.]

Re: Which Spark Plugs

So what is the story regarding damage to the system by using a resistor type plug?

never heard that story and even F-1 uses resistor plugs because of all the electronics in those race cars

[Louis T.]

Re: Which Spark Plugs

Hi Larry,



At the moment the spark jumps the gap it causes a high frequency burst of energy known as RFI (radio frequency interference). Resistor spark plugs were introduced in the mid 1960s (placing a resistor within the spark plug suppresses the RFI). In addition to reducing electrical noise for radio, television and mobile telephones, etc., many modern ignition systems require resistor plugs to stop electrical noise from interfering with the vehicle's on-board electronic control units (ECUs). In fact, some must use resistor plugs for a proper "talkback" to the electronic ignition. If non-resistor plugs are used in place of resistor ones in one these vehicles, the result can be poor performance, malfunction, and in some cases immobilization of the vehicle.



Regards,

Louis

[Joe L.]

Re: Which Spark Plugs

So what is the story regarding damage to the system by using a resistor type plug?

Larry-----


If using resistor-type plugs was a problem for TI-equipped Corvettes, then a whole lot of such cars were in trouble from the get-go. All 1969-71 Corvettes were originally equipped with resistor-type plugs, INCLUDING those also equipped with TI.

[Larry T.]

Re: Which Spark Plugs

All of this sounds good and I appreciate it. I just want to be careful since I read that the coil can be damaged. I should have put this in my original post, but the comment specifically stated:

"be careful about substituting resistor plugs (r43xls) for nonresistor (43n) - if you have resistor wires too- the old coil can be overloaded"

Does that make any more sense? If so, how can I distiguish the types of wires? Mine were on the car when I purchased it, although I am certain they are reproduction. The wires are labled "Packard Radio TVRS LR 3Q65" they also have a lightning bolt looking image with an H in between.

Thanks again for all of the input.

[Clem Z.]

Re: Which Spark Plugs

All of this sounds good and I appreciate it. I just want to be careful since I read that the coil can be damaged. I should have put this in my original post, but the comment specifically stated:

"be careful about substituting resistor plugs (r43xls) for nonresistor (43n) - if you have resistor wires too- the old coil can be overloaded"

Does that make any more sense? If so, how can I distiguish the types of wires? Mine were on the car when I purchased it, although I am certain they are reproduction. The wires are labled "Packard Radio TVRS LR 3Q65" they also have a lightning bolt looking image with an H in between.

Thanks again for all of the input.

even MSD tells you not to use solid plug wire because the interference from it will cause trouble with the MSD electronic ignition box

[Clem Z.]

Re: Which Spark Plugs

Larry-----


If using resistor-type plugs was a problem for TI-equipped Corvettes, then a whole lot of such cars were in trouble from the get-go. All 1969-71 Corvettes were originally equipped with resistor-type plugs, INCLUDING those also equipped with TI.

if i remember correctly the early L-88 came with packard 440 wire. don't quote me as that was a long time ago.

[Joe L.]

Re: Which Spark Plugs

All of this sounds good and I appreciate it. I just want to be careful since I read that the coil can be damaged. I should have put this in my original post, but the comment specifically stated:

"be careful about substituting resistor plugs (r43xls) for nonresistor (43n) - if you have resistor wires too- the old coil can be overloaded"

Does that make any more sense? If so, how can I distiguish the types of wires? Mine were on the car when I purchased it, although I am certain they are reproduction. The wires are labled "Packard Radio TVRS LR 3Q65" they also have a lightning bolt looking image with an H in between.

Thanks again for all of the input.

Larry-----


The wires are radio-suppression type. The "TVRS" means "television and radio suppression".

All 63+ Corvettes used radio suppression spark plug wires (i.e. "resistor" spark plug wires) except, possibly, L-88. For 1969-71 all also used resistor-type spark plugs. So, there were many 1969-71 Corvettes built which were equipped with TI, TVRS wires, and resistor spark plugs.

There was a change in 1969 as far as the TI system was concerned. However, I don't think there was any change which affected the compatibility of the system with resistor spark plugs and/or TVRS wires. The change was that 64-68 used an amplifier with a plug connection for the TI harness. 1969-71 used an amplifier with an attached "pigtail" which connected to the TI harness. I don't know why this change was made but I don't think the system changed in any other significant or functional way.

[Clem Z.]

Re: Which Spark Plugs

Larry-----


The wires are radio-suppression type. The "TVRS" means "television and radio suppression".

All 63+ Corvettes used radio suppression spark plug wires (i.e. "resistor" spark plug wires) except, possibly, L-88. For 1969-71 all also used resistor-type spark plugs. So, there were many 1969-71 Corvettes built which were equipped with TI, TVRS wires, and resistor spark plugs.

There was a change in 1969 as far as the TI system was concerned. However, I don't think there was any change which affected the compatibility of the system with resistor spark plugs and/or TVRS wires. The change was that 64-68 used an amplifier with a plug connection for the TI harness. 1969-71 used an amplifier with an attached "pigtail" which connected to the TI harness. I don't know why this change was made but I don't think the system changed in any other significant or functional way.

the TI amp are all identical inside as far as parts. i think the pigtail was added for the ease of installation on the assy line