I see 2 types recommended - Bosch WDC. and. WDRC - non-restistor vs resistor

Which is the correct plug and what are the differences?? - engine performance, radio reception, etc

Confusing issue - and then on FCP and IPD there are VOLVO SPARK PLUGS - but we don't know if resistor or non- resistor.

Thanks for the help!!!

Although a 240 will likely run on anything = BRICK

http://www.ngk-sparkplugs.jp/english/techinfo/qa/q08/index.html

This article may be of interest? As well as interference with radios, it seems interference with vehicle computer systems may be an issue?

Owen F

To suppress the high tension ignition spark noise in your AM / FM radio receiver?

Does using ...

- resistor wires / no resistor plugs
- no resistor wire / resistor plugs

... serve other purposes than radio receiver noise suppression?

Occasionally and mistakenly I used the paired combo ...

- resistor wires and resistor plugs
- no resistance wire / no resistor plugs

... without ill effect so far as I could discern.

Did not document the plug condition for the recurring center electrode condition (how short is it and is it rounded) inspection and the gap reset, with a little nickel anti-seize on the thread and apply reduced torque.

Do the resist / non-resist plugs or wires at the plug end use that top of the plug thread on cap thing or no?

I like the Bosch Supers (copper) and the NGK coppers. Found a set of unused Volvo brand plugs for US B230 F in a junkyard years ago. Hope to use these.

I have multiple sets of practically unused spark plug wires I pulled from junkyard Volvos. Probably why I mixed these up with the plugs I'd installed in the engine.

And then you can have the alternator whine ... yet no more Volvo factory Blaupunkt or 1982 Panasonic cassette / radio anymore. These newer radios from like the late 1990s onward seem to not relay the high tension spark and also the alternator whine sound though the speakers anymore. Maybe a little through AM?

I added extra braided ground straps between the valve cover and bulkhead firewall. And used beefed up ground wires between the alternator and the engine.

Amazing the terrible last stand service attempts before the poor rear wheel drive Volvo is sent to the salvage yard. Probably some sort of engine control issue that is easily diagnosed and fixed to pass CA-smog or get the thing running again.

Happy Mundane.

Pain in my Neck Boyeeeeeeee.

As far as I know the resistor business is for radio - especially AM noise. I'd add to what I wrote, this as well -- basic copper core wires work best and you'd be surprised at how long they can last -- maybe not at 100 percent but well enough for the motor to run properly. As an example -- when I put my 1980 245 on the road in 2000 I went to change the plugs as a matter of course. Three of them came out with no trouble but one was stubborn. Since the three already removed looked OK I put them back in so all 4 would be the same. Years later my friend suggested trying to remove that stubborn plug with the motor hot and it did come loose without drama. Those plugs, now with over 175k on them continued to perform well - no issues starting, continuing with consistent good gas mileage despite now having center electrodes as small nubs. Of course at that point the car got new plugs. -- Dave

in 85 or so, there was a bulletin stating that resistor plugs, non-resistor wires and a ground strap from the valve cover to the firewall is now oe and to be retrofitted to previous engines. wr7dc ids the plug for the wires with rubber boots, the metal shells were discontinued.

I'd like to sum up because there's good info in the posts already written but here's all of it wrapped up in one. "In the beginning..." When the 544, 122 and 140 models were sold Volvo used a copper wire wrapped in a red covering. Those ignition wires used the brown plastic spark plug connector as did VW in their Beetles and Buses. There was a resistor built into those plastic connectors to compensate for the copper wire and radio interference that ensued. With introduction of the 240 models the resistors were moved to those metal shielded connectors most newer (I'm talking relatively speaking) Volvo owners would be familiar with. The Bougicord wires-and others like it- do not have the resistor so "resistor plugs" should be used. I think the resistance for the metal shielded wire connectors is something like 5-7K.
While Volvo recommends Bosch plugs I've used NGK ever since working at a Honda dealership--that was early in the production of the CVCC motors in Civics and Accords. They had horrible problems with the complicated 3 barrel carburetors used for the CVCC system. Cleaning carbs and resetting float levels was a big part of any Honda tech's day. Float level was set by an external adjustment screw. The procedure was to warm the engine, then, in stages, raise the float level till the motor floods - then back off a specified amount (depending on the model). With the motor flooded and the adjustment made you'd now restart the motor to check for an even idle -- that done, job finished. And while completely flooded, start they did. They used NGK plugs and I was sold - been using them ever since. Try that with a Bosch plug and you had better have a fresh dry set available. Anyone who has ever owned an SU HS6 carb equipped Volvo can testify too the annoyance of a flooded motor due to either sticky needle valves or the overuse of the "choke" (actually an enrichment device to add fuel rather than restrict air like a normal thing we call a choke). That's the whole scoop. Resistance wires or resistor plugs--one but not both. -- Dave

Hi,

You just want to run the standard plugs recommended by the owners manual or most any reputable manual for these engines.
HEAT RANGE number is the most important thing to watch for. The deposits on the plugs tell the story!
VOLVO did their homework years ago working with Bosch.
Depending on any oil burning or compression issues you can move that around if necessary but you will find out that standard works best overall!

I cannot answer the question about resistors or not with any plugs.
Spark plug wires can act as transmitting antennas! The plugs are like inside the engine and in my mind shielded.
In old days of solid wire versus newer carbon resistance spark wire, the free “over the air media devices” got hit if a car was outside in the driveway. You got popping sounds on radios and flickers on the TV screen.
The media in most cars today are totally different. No electron vacuum tube absorbers!

The best luck I have had is just plain ole Bosch standard electrode that use to sell in a four pack that got consolidated into one number 7900.
Some may call them silver on the BB. There maybe some nickel in them but not dollars of other stuff. (:)
I have learned to stay away from platinum, iridium and just keep my money in my pockets and not put it in theirs!
Nickel is a high enough heat resistant element all by itself. Some went adding copper plus into the mix to promote sales and reduce the amount of nickel. Metals are a money game.
These plugs may have both and deliver a fat enough spark to do the job and stay reliable.

The other tips, in the more fancy plugs, are so small and short up in the body of the plug you wonder just how did they get the rest of the electrode to deliver the spark down to it?
Works better, who knows, but my beliefs say, the Answer is only marketing!
The prices are all over the place, If you shop about you will see it and that makes it a “game” on the consumer.

Your choices are as plentiful as your money for them!

Phil

My 1981 and 1982 240 were originally using W7DC spark plugs with blue wires at the distributor.

When I could not find these W7DC anymore I switched to WR7DC. But also replaced all the plug wires with the common black rubber Bougicord.

I had to get rid of the Volvo blue wires which had the metal covering at the plug connectors. They have resistance instead having it in the spark plugs I beleive.

Hi
What can I say?

I know about those metal capped ends and I liked that you could actually grip them and the wire would not be stuck to the porcelain of the spark plug like the rubber boots do.

I believe you are right as racing performance wires may or may not have a resistance built in.
I have read that some wind their cores differently to cancel out the effect of them becoming an antenna.

The blue or black is eye appeal thing. Eye appeal is sales appeal! Ask any pastry baker!

I have never understood why they in a resistance that would supposedly restrict current flow anyhow.
Sounds like its almost counterproductive, doesn’t it?

When I was a young shorter person a lot of things were way over my head for me to understand.
Now that I’m older and taller, it’s still about the same, because there are so many more subjects one can never learn about.
This world is so dynamic how can anyone get bored enough to ever want to be put into prison is beyond me and yet we have zoos?
Make weapons but want peace, very confusing!

Keeping a Volvo running, a children’s play on the BB and we are all still learning!

Phil

You wrote: "I have never understood why they in a resistance that would supposedly restrict current flow anyhow."
Sounds like its almost counterproductive, doesn’t it?

Actualy one system has resistance in the wires with W7DC spark plugs and the other other has resistance in the spark plugs itself in the WR7DC.

This what I undestood from post on this board. Otherwise WR7DC spark plugs with the original resistance wires is doubled. Not good I suppose although it could work under ideal conditions.

I beleive the blue Volvo wires had about 6k ohm resistance.

Have a good day.

Your explanation of spark plug/wire resistance was right on. Your English continues to improve, Roland. Hard to believe it is your second language.
--
Will I buy another Volvo??? We'll see....