plug extensions resistance 308

Hello from Germany,

I searched the archives but didn't find a 100 % answer for my question.

Ten years ago I replaced all 8 spark plug extensions on my carbed 308 GTB with the later electronic ignition system.
Now I found two of them rusty. They still work fine but I would like to replace them.
Back then in 1996 a official Ferrari dealer supplied me the #116613, which are red. Originally I had black ones.
Now for the first time I compared the resistance of some of the original Euro carb plugs with the red ones. The old, black ones have a resistance of 10 k Ohms, the red ones only 2 kOhms.
When I search the web catalogue of Ferrari UK the red #116613 are listed for the australian version of the 308 GTB/S.

Now two questions come to my mind; why is there such a significant resistance difference for different markets and - more important for me - what is the correct resistance all over from the distributor to the spark plugs.

On a different thread I read, that resistor cables are mandatory for the electronic ignition cars. Why can't I take copper cables with zero resistance and some low resistance plug extensions ?

Best Regards and thanks in advance

Martin

 

Martin, as I understand it you must have some resistance in there to avoid radio interference, (not only your radio but other's also). So that's either resistance plugs, resistance wires or resistance connectors.

My carb 308 with Crane type ignition has the red connectors at ~2 k Ohms and the leads have a further ~1 k Ohm.

Ein gute Anfang aus der Schweiz..

 

Hello Martin,
Just today I checkt my plug extensions on my '77 308GTB carb with points and they are original red and have a resistance of 1.5 K ohms hope this will help a little bit.Rob

 

Hello Richard,

this is exactly what I have, but still leaves me wondering, why it is not possible to use copper leads without any resistance, which are also much more reliable.
I think for suppression of radio interferences some 2 kOHms plug extensions on zero resistance leads would be sufficient.

Hello Rob,

and how much is the resistance of your leads ? It seems, like on mine, that on your car the extensions have been renewed too, because originally the Euro carbed 308 had the black ones with 10k.

Best Regards

Martin

 

What an interesting thread guys, I was thinking of these questions myself. There are some smart people on here that should be able to give some insight into ignition system physics and what would work best under what conditions, etc. It seems we have the radio interference issue, which if really powerful could effect not only our electronics in the car, such as radios, cell phones, radar detectors, etc., but those around us as well. Be nice to know how to have most bang reliably without causing to much trouble.

I know on aircraft, all high voltage wiring and spark plug leads are shielded with braided wire that is grounded, to allow sensitive electronics to work reliably. Perhaps some of that 60 year old technology could be useful? hopefully not a highjack, but I have always found it interesting that old cars, and well made european cars, used braided copper ground cables off the battery. Some say they are junk, but old times say they work like a static whip. Anyone know w technical reason?

Should we safely assume that lower resistance between coil and plug, gets a hotter and more reliable spark to go through? More resistance seems like it would be easier to force the energy to leak out of the wire somewhere.

 

FWIW!!!
I had a friend come up with a set of MSD Superconductor wires for a aftermarket ignition on a 2 valve Mondy ('82) They were originally designed for the Chrysler Hemi, and the resistance value was lower than anything on the market.
I swapped them over to am '85
308 that was having ignition problems (at the request of Gil, an Electromotive technician) The resulllt????
NO EXTENDERS TO BURN out. the Boots fit great, and the car fired and purred. Minde you the Mopar monster hemi used a hi dielectric long spark plug terminal. You could pull on the top, as it was one piece and never a hassle in lining up that add on.
On a lighter note... Weren't extenders originally offered in mens magazines?
I would note that the Electromotive tech was not a fan of Taylor wires a "his opinon".

 

don't want to hijack my own thread, but there are jerks over here who call the whole 308 an 'extender' in that sense you mention above.

Back to the subject; thanks so far. I hope for further, numerous opinions.

Best Regards from Germany

Martin

 

I've been using an Electromotive DIS for the past 10 years or so. I did away with the extenders per the race shops recommendation. Electromotive also recommends carbon core wires (needs to be 3k - 5k ohms/foot). Fortunately, these are relatively cheap wires, anywhere from $40 - $100 for a universal set. I've never had any problems since, but it is a little tricky pushing the boots on to the plugs w/o the extenders (especially on the front bank).

 

Would these be simular to Moroso wires for the Hemi, with the whole wire/boot/extension all one peice of silicone? I was told by someone they were a bit to long and needed some nipping off the end to fit down tight. Thoughts or experience? Durability? Look somewhat stock?

 

I am running solid core magnecor wires and will check my extenders this weekend, I have the black ones but were told they had less resistance....????&*^%$

 

Kermit you are wrong with respect to Electromotive's recomendation of wires for their systems. On HPV,HPX, XDI & TEC systems they reccomend Spiral Pro wires & Magnecor wires. It even states on page 7 & 8 on the XDI manual right down to the ohms per foot. You are giving people wrong advice with respect to ignition wires on Electromotive products. Its in the manuals & they are downloadable from Electromotive's website & also my website. MSD wires are not reccomended for a any Electomotive units.THE RESISTANCE IS NOT CORRECT. If you are looking for the finest in quality ignition wires, they are made by Magnecor period.

Here is the actual text from page 8 of one of the Electromotive manuals
QUOTE:


Due to the extremely high energy in the XDI coil charging circuit, spark plug
wires may wear out faster than with a standard ignition. As such, it is recommended that the wires be checked periodically for carbon tracking caused by a breakdown of the internal conductor element. Looking at the plug wires in a dark area and wetting them with a spray bottle of water will reveal carbon tracking. Pay close attention to the exposed section of the spark plug (where the rubber boot ends) during the test. To maximize spark plug wire life, keep the lengths as short as possible (i.e. mount the DFU
as close to the engine as possible). Replacement of the wires on an annual basis is recommended for high-rpm/high-horsepower applications.
For an extremely high-quality wire with excellent noise suppression, we
recommend the Magnecor brand. Specifically, their “Electrosports 80” 8mm wire is very good with our system. Custom wire lengths and ends are available from them so you will not need to crimp the wires yourself. They can be reached on the web at:www.magnecor.com. Taylor Pro-Wire Silicon Resistor wires also work well. END OF QUOTE.

 

o.k., now I have some brand recommendations, but unfortunately these aren't available here in Germany.
So allow me to put my inquiry in new, different words.

What would happen with the stock 308 electronic ignition, if you would install copper leads with, say, 2kOhms plug extensions.
Any damage or malfunctions of the ignition unit, due to overload or interferences or similar ( amplifier, etc. ) ?

Unfortunately the FChatter, who stated, that resistor leads are mandatory for the later electronic ignition, doesn't chime in here yet, although I have asked him about the reasons for NOT using such leads.

Best Regards

Martin

 

now i am confused....

what is the correct extender to use on a 77 308 with both sets of points intact? my car has a high rpm miss on the forward bank. we know the dwell and the points gap is off. i am going to fix that.

the wires are ancient and need to be done. the extenders are black and look ok, but how do you know?

i had a set of V8 mallory radio suppression wires i cut to length for the 308. have not fitted them yet as i must pull the dizzys to set the points gap first and clean / inspect the caps and rotors.

i just installed a fresh set of NGKBP6ES plugs, gapped to spec. car runs better, but the miss under load is still there, until i address the points.

i am planning on going with the dual crane x700s and installing both pick ups in a single dizzy. ( near future?)


what is the ohms range one should get for new wires?


should i get the red extenders over the black?

thanks......

 

first off why are you running two points? Even in CA the car pasesd emisson with one, second if you dont need the radio use solid core, they work great with standard ignition. I have neve had a problem ever!! well aat least with the ignition

 

My 78 308GTS had sort of tan looking original extenders. I ordered new replacements from T.Rutland's and they sent me black ones...never checked the resistance, but doubt they had any...as I had terrible interference when using an FRS (fm) two way radio. I swapped out the NGK BP6ES for BPR6ES plugs and no more radio interference. Stuck with resistor plugs from then on...including the NGK EVX ones (with Crane XR700 ignition).

 

hi Robert, my new to me GTB is totally original. i just removed the thermoreactor last week for safety reasons. unmolested 308s are hard to find and i am not going to screw this car up. if i can run both sets of points and the micro switch as is, i will. if i have to start buying points, caps and coils i am going with electronic ignition. i am just trying to get it to run right with what i have without molesting the car. we have no emissions testing here where i live, so that is not an issue for me.

i may go with Taylor or Magnacor wires, i have a new V8 set of Accel and Mallory wires from my muscle cars days, so i cut up one of those sets. i do want to ohm them before and after hooking them into the caps to make sure i have a proper connection.

 

ya know, my radar detector freaks out in my 911 (laser) sometimes.... i wonder if its the wires? i am running NGKBP6ES plugs in it too. i just ordered a rebuilt air fuel meter as its runninf a bit lean according to the LM-1. i bet the wires are old and breaking down!!! time for some Jacobs wires on the 911 !

 

okay i decided last yr to find out what was really inside these things. so i cut one open, result? nothing. it's a solid peice of plated brass. the rhinite housing is what ends up getting burn holes in it due to arcing of the spark. my opnion, stop using them. there is far better and newer technology wires and connectors that fit and you'll avoid the issue.

 

Reaper,

You want 116613 (red). Get the $8 from allferrariparts.com 2kOhm resistance. OEM was black but the new re-manu ones are red.

That's what I'm running (just put them in last month) and I still have the dual points as well. I also replaced my plug wires with an Accell set per that "plug wires made easy" post from last year.

My car runs fine up to 7700.

Fix your pionts or replace them with a pertronix or crane and your car will run fine as well.

 

I did a search and wasn't sure about what I found. Can you post a link about "plug wires made easy"?

Thanks,
Seamus

 

thank you !

 

im a stickler for autheticity but the euro cars did not have the 2 points and I feel that with the reactor and pumps on damage is caused to the engine components (hoses, wires, etc) from excessive heat. Im not sure many cars still have the two points intact, but to each his own. I know this for a fact the engines wwere never meant to run this way and were only added as a band aid to meet US regs at the time. I have heard many stories of plug fouling bad running etc but with the set up I have using the magnecor solid core wires, I have had no issues in 13 years. I have a casette and never listen to the radio and not sure if I care about affecting other cars around me. Taking the second set of points out seem way less radical than scrapping the original system for a electronic one which seems wrong to me. A well set up car will run great with the points JMHO

I do listen to the radio in my other car and since the advent of cell phones I have a hard time picking up stations I could get easily years ago.

Rob

 

apologies for ressurecting an old thread, but i have a problem with at least one of my baby's spark plug extenders (1980, 2v, carb GTS).

how do i measure this ohm thingy with my "multi-meter" ?

many thanks in anticipation.

david

 

David; that's simple. Select the Ohm function, and if it's doesn't have the auto-range feature select an appropriate range. Just measure between the plug end and the wire end.
IIRC - I'm not quite sure at the moment; the correct value is somewhere between 5 and 10 kOhms. But if this is of interest, I could just measure one of my spares.

Best Regards from Germany

Martin

 

Martin,

PM me.

Mark