Resistor sparkplugs

Moderators: 330GT, abrent

michaelbalk330
Posts: 102
Joined: Fri Feb 06, 2015 8:28 am

Resistor sparkplugs

Post by michaelbalk330 »

Bought some ngk bp7es online. Had some trouble finding non-resistor plugs. One vendor sent me bpr7es. I have 1k resistor boots in perfect condition. What harm is there in using resistor plugs when non-resistor type are specified.?

Michael.
Michael
1967 330GT #9693
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1971 porsche 911e
michaelbalk330
Posts: 102
Joined: Fri Feb 06, 2015 8:28 am

Re: Resistor sparkplugs

Post by michaelbalk330 »

So I just read the recent post below mine on ignition coils and realized I should mention my car runs an electronic ignition set up from the 70s using Motorola boxes and a lobe sense pick up in the distributor,.I prefer not to fry those boxes by putting in the wrong spark plugs that’s why am asking
M
Michael
1967 330GT #9693
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1971 porsche 911e
User avatar
tyang
Posts: 3925
Joined: Wed Nov 27, 2002 10:28 pm
Location: New York
Contact:

Re: Resistor sparkplugs

Post by tyang »

I'm just speaking out loud, so please someone correct me if I'm wrong. Electronic ignition system like the motorola boxes were basically solid state switches that took the switching signal from the shutter, or points, and used a solid state switch to collapse the field on the coil. Can the resistance of the spark plug adversely affect the operation of the box?

Tom
'63 330 America #5053
michaelbalk330
Posts: 102
Joined: Fri Feb 06, 2015 8:28 am

Re: Resistor sparkplugs

Post by michaelbalk330 »

found 2 things online that sounded reasonable:
first was pic from NGK attached stating it won't affect performance.
second was this:
drawback to resistor plugs as i applies to Older cars, esp magneto pre60s cars... It raises the voltage to the point that it can cause insulation failure in older coils. Today's coils are built to handle the extra resistance and higher voltage imparted by resistor wire and plugs. Today's auto ignition systems typically make over 60,000 to 100,000 volts!:eek: Most of our old engines made between 10 to 20,000 maximum. Older systems cannot overcome that resistance. Spark (electricity) will find the easiest path to ground. if resistance is too high, it will jump thru the old type shellac used on older mag and battery type coils, thus shorting out the secondary wiring. On some engines, this extra resistance will also short out on distributor caps, and if the resistor wiring is old, it will also break thru the insulation sleeve on the wire itself.

would love to hear from some others... i going to stick with non resistor plugs unless I hear from knowledgable others that its OK
Screen Shot 2020-04-12 at 10.00.21 AM.png
Michael
1967 330GT #9693
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1971 porsche 911e
DWR46
Posts: 573
Joined: Tue Sep 22, 2009 8:23 pm

Re: Resistor sparkplugs

Post by DWR46 »

For the pre-Testarossa cars, non-resistor plugs are the best approach. You want to get as much spark energy to the cylinder as you can. As a general rule, we stay away from resistor plugs.
michaelbalk330
Posts: 102
Joined: Fri Feb 06, 2015 8:28 am

Re: Resistor sparkplugs

Post by michaelbalk330 »

dyke.. thanks!
Michael
1967 330GT #9693
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1971 porsche 911e
DrewA
Posts: 90
Joined: Wed Sep 04, 2002 10:15 am
Location: Tuscaloosa, AL

Re: Resistor sparkplugs

Post by DrewA »

Resurrecting an old post. I've been running NGK BP6ES plugs in my Daytona for years with good results. Evidently NGK is no longer making this plug. I hesitate to use the BPR6ES as my car is a EURO (without Dinoplex) and I'm a little worried about getting enough energy to the tip of the plug.

What are you folks using?

Thanks,

Drew Altemara
Jimmyr
Posts: 416
Joined: Thu Aug 19, 2004 11:20 pm
Location: Scottsdale, AZ

Re: Resistor sparkplugs

Post by Jimmyr »

The reason for resistor plugs was their ability to reduce ignition noise in early AM and SW radios. The 1K resistance has little effect on system performance or load on components. I also agree with Dyke that the non resistor plugs are best for the earlier cars as they allow a slight increase in plug voltage.
tim
Posts: 332
Joined: Tue Sep 03, 2002 2:48 pm
Location: sacramento, ca

Re: Resistor sparkplugs

Post by tim »

Greetings.. I just had this exchange with NGK

I have been using NGK BP6ES spark plugs for perhaps 50 years and I see they now have a different part number. The old system described the spark plug but the news just a number. Pity. I also see the new number is discontinued and the suggestion is a resistor unit. My experience with resistor spark plugs hasn't been great in my older vehicles (50 and 60's sports cars) Will it be possible to get non resistor spark plugs in the future?


Thank you for your patience, at this time the only plug available is NGK 7910 B6ES-11 Nickel Spark Plug, this is a non resistor and non projected firing tip spark plug that is pre-gapped at .044" however you can adjust the gap to the specs you need.

Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS
Jimmyr
Posts: 416
Joined: Thu Aug 19, 2004 11:20 pm
Location: Scottsdale, AZ

Re: Resistor sparkplugs

Post by Jimmyr »

Tim, just checked eBay and plenty of the BP8ES offered. Jim
DWR46
Posts: 573
Joined: Tue Sep 22, 2009 8:23 pm

Re: Resistor sparkplugs

Post by DWR46 »

Jim: "8" is way too cold for a street engine. The BP6ES is the BEST plug for street motors.
Jimmyr
Posts: 416
Joined: Thu Aug 19, 2004 11:20 pm
Location: Scottsdale, AZ

Re: Resistor sparkplugs

Post by Jimmyr »

Dyke, Tim, my typing skills are poor, yes we all know and use BP6ES plugs. I noticed this after I saw it later. It seems Tom does not have an edit button to use like the other sites have. Ebay does have the correct BP6ES available.
DWR46
Posts: 573
Joined: Tue Sep 22, 2009 8:23 pm

Re: Resistor sparkplugs

Post by DWR46 »

Jim: At least you can type. I took a typing class in summer school between my junior and senior year. This was the same summer I got my first Alfa. To this day, I have never been able to understand why I have NO typing skills.
enio45
Posts: 744
Joined: Wed Jul 02, 2003 6:56 pm
Location: Gilbert, AZ

Re: Resistor sparkplugs

Post by enio45 »

If I may, Id like to ask.....related to a 330 GTC

we are prepping a newly build engine, i need to purchase the plugs, wires we are currently making, and we did convert one distributor to electronic.......

Questions:

1. Which plug would you suggest
2. Wiring the distributor - still need the square resistor block wired in?
3. Coils are the orig MM style coils

Appreciate the thoughts......
Ed Montini
330 GT 2+2 Series II - 8289
58 Ellena - 0855GT - orig drivetrain
61 250GTE - 2421
enio45
Posts: 744
Joined: Wed Jul 02, 2003 6:56 pm
Location: Gilbert, AZ

Re: Resistor sparkplugs

Post by enio45 »

PS.....no radio installed FYI
Ed Montini
330 GT 2+2 Series II - 8289
58 Ellena - 0855GT - orig drivetrain
61 250GTE - 2421
Post Reply