Spark plug opinions

[GH85Carrera]

I am looking for opinions, and I think this group has opinions.

I want to replace the plugs on my 85 Carrera and I was hoping to get the input from the professionals like Grady, Zimmerman & John Walker and the like.

Pelican parts lists the Bosch WR7DC+ as the proper plug for my car.

Now for the opinion part how many of you would use that Bosch plug and how many would use something else?

What plug would you use and why do you feel it is the best choice?

[Rot 911]

A popular choice on the board is the NGK BPR6ES for the 3.2 engine. Inexpensive, copper, works.

[stlrj]

Anything but platinum.

[IROC]

Originally Posted by Rot 911

A popular choice on the board is the NGK BPR6ES for the 3.2 engine. Inexpensive, copper, works.

I'm going to go buy plugs today. NGK for sure. I use BPR7ES for my 10.3:1 compression, but yes, the BPR6ES is correct for the US-spec 3.2. I've used them for years - no complaints.

[GH85Carrera]

Originally Posted by stlrj

Anything but platinum.

What exactly is the reason to stay away from Platinum?

[Flat Six]

Originally Posted by IROC

I'm going to go buy plugs today. NGK for sure. I use BPR7ES for my 10.3:1 compression, but yes, the BPR6ES is correct for the US-spec 3.2. I've used them for years - no complaints.

I've been using NGK's (BPR6EY) with no trouble at all -- am very happy with them. The Y plug is identical to the S plug except the Y plug has a V-grooved center electrode, providing a slightly larger surface area for the 2.5 mm electrode and -- some say -- potential for a slightly larger flame kernel. Don't know if I buy that, nor can I tell any real world seat-of-the-pants difference between the Y plug and comparable S plugs. Both work really well for me (stock 85 3.2).

HTH

Dale

[DRACO A5OG]

+1 on Copper OEM spec.

I had platinum and irridium bot did not work as the old skool copper.

[patssle]

What is the differences between BPR6ES/BPR7ES and BP6ES/BP7ES? Does the R mean something important?

[Flat Six]

Originally Posted by GH85Carrera

What exactly is the reason to stay away from Platinum?

IIRC, platinum (and iridium, and I'd guess other exotic metal) plugs use a very fine wire for the center electrode, due primarily I'd guess to the rarity and expense of these precious metals.

While many of the physical dimensions of spark plugs haven't changed in the last 45 years, ignition and engine management systems have. Though small diameter, the electrode tips are designed to burn off contaminants and oxidation quickly (just like a MAF sensor, I'm told). And the smaller electrodes perform pretty well with modern vehicles' more precise engine management systems (more consistent/precise engine temp control [H2O], knock sensors, etc.).

Add to that the fact that head and combustion chamber design has evolved to the point where access to spark plugs is so limited on some newer cars it's darn near impossible to R&R. And manufacturers want to increase maintenance intervals by a wide margin (50K-60K miles before first plug change), so market demands have also driven plug design, primarily for longevity IMHO. That's why we see so much platinum, iridium, unobtanium, etc. in electrodes. Under these (more) tightly controlled and precise combustion conditions the smaller electrodes can be used for more miles compared to copper.

But in an air-cooled engine with far less precise engine management (and, um, uniquely shaped piston domes) the larger electrodes offered by copper plugs seem to provide more consistent and reliable ignition -- at least that's the explanation I take from the anecdotal evidence of copper plug success I read about here.

Just my observations, YMMV.

Dale

[Flat Six]

Originally Posted by patssle

What is the differences between BPR6ES/BPR7ES and BP6ES/BP7ES? Does the R mean something important?

B = 14mm thread
P = Projected insulator
R = Resistor
6/7 = Heat Range (lower number is hotter plug w/NGK; other mfrs may differ)
E = 19mm reach (thread depth)
S = Standard electrode

Bosch WR7DC+

W = 14mm x 1.25 thread
R = Resistor
7 = Heat range (Bosch is reverse, lower number is colder plug)
D = 19mm reach (thread depth)
C = Copper electrode
+ = Bosch 'Super Plus' technology -- tapered nickel-chromium ground electrode

[GH85Carrera]

So there is a real difference between the R and non R NGK plugs. That is good to know. The flaps employees only know what is on the computer.

[IROC]

Originally Posted by GH85Carrera

So there is a real difference between the R and non R NGK plugs. That is good to know. The flaps employees only know what is on the computer.

I've used both and didn't notice a difference.

[patssle]

Originally Posted by IROC

I've used both and didn't notice a difference.

Yeah that's what I'm wondering, is there a real world difference for our engines?

[pete3799]

flaps came up with an NGK R something or other for my 3.0.....they work fine.

[Flat Six]

Originally Posted by patssle

Yeah that's what I'm wondering, is there a real world difference for our engines?

Back in the olden days, I think, resistor plugs were used primarily for ignition noise suppression -- so you wouldn't hear it through your radio. These days I think it has more to do with protecting other sensitive electronics and -- potentially -- overall resistance between distributor cap and cylinder.

Brings up a thought, though -- has anyone measured the difference in resistance (center electrode) between two otherwise identical plugs? (e.g., BPR6ES vs. BP6ES)?

[GH85Carrera]

I have never used a NGK brand plug. I have noticed many people on this board seem to prefer them. It may come down to which FLAPS has which in stock.

[IROC]

Originally Posted by patssle

Yeah that's what I'm wondering, is there a real world difference for our engines?

I just pulled my old ones to check them and they are actually BP7ES - not the "R" ones. I don't have a radio, so I don't know if that makes a difference, but the plain BP7ES work fine in my car...

[Flat Six]

Originally Posted by IROC

I just pulled my old ones to check them and they are actually BP7ES - not the "R" ones. I don't have a radio, so I don't know if that makes a difference, but the plain BP7ES work fine in my car...

Mike, even if you had a radio you still might not notice any ignition-induced noise with the non-resistor plugs; some cars shield ignition wires instead and that sometimes is enough.

I run what I got, and that's a resistor plug, and it works great. Personally, I wouldn't replace a set of non-resistor plugs w/resistor plugs just because. I'd do it if I had radio interference, or if it was time anyway and that's what I had on hand. Just my $.02.

Dale

[GH85Carrera]

I did a little digging tonight. I found this problem.



It is not the plug that is for sure. You can see the green corrosion on the wire & the connector. I will likely replace the plugs because they are so cheap and I have the air cleaner off already.

Now I have to decide if I want to spend a big wad of cash for new wires or just clean theses up and let it ride.

[DRACO A5OG]

Can it be repaired properly?

Dang, you must get alot of rain, huh?