Worst spark plugs ever

[JohnJL]

I was doing some preventative maintenance to an 85 911 and found the plugs in this condition...the motor was running OK but will obviously benefit from a new set of plugs, wires , rotor and cap. I have never come across plugs in such bad shape...they are Bosch WR70P Platinum of unknown age...one pic below is next to new Bosch WR7DCs

[theiceman]

those plugs look absolutely fine... they are just a different style to your replacements. They live in a harsh environment.

[LJ851]

Originally Posted by JohnJL

I was doing some preventative maintenance to an 85 911 and found the plugs in this condition...the motor was running OK but will obviously benefit from a new set of plugs, wires , rotor and cap. I have never come across plugs in such bad shape...they are Bosch WR70P Platinum of unknown age...one pic below is next to new Bosch WR7DCs

Looks like a typical platinum plug to me, what do you see wrong with it ?

[proporsche]

WR7DC are the correct plugs for your 911 ..if you do not use catalyst you should get W4CC plugs

Ivan

[RetroSC]

I'm guessing you think the plugs have burned off the electrode, like you see on the new plug?? If so, those platinum ones are different and have no protruding electrode, they look like that when new. So other than being dirty, they look just fine.

[JohnJL]

Huh, all the platinum plugs I recall seeing in the past had fine wire electrodes, I assumed these burned off. They look very different to anything Ive seen before.

In with the WR7DCs.

Ivan, are the W4CC really 3 ranges hotter? Why the difference due to cat or not?

Thanks!

[proporsche]

yes for non cat WR4CC....i have never liked those so called platinum plugs.
I just wonder if you are able to get the WR4cc plugs?

Ivan

correction, i keep forgetting the R

[porschyard]

Originally Posted by JohnJL

Huh, all the platinum plugs I recall seeing in the past had fine wire electrodes, I assumed these burned off. They look very different to anything Ive seen before.

In with the WR7DCs.

Ivan, are the W4CC really 3 ranges hotter? Why the difference due to cat or not?

Thanks!

The Bosch plug heat range is higher number is hotter and lower number is colder. The WR7DP is not a true platinum plug and is reflected in the ( cheap) price. Look at the price of a set of say W3DPO which are true platinum and you will see the difference. I agree with retro that other than looking like they have been in there for a while they look fine but also agree they are uneccessary and would just stay with either the WR7DC Bosch or a BPR6ES Ngk Richard

[thsupernge]

I have an extra set of the WR7DCs that are about 2 months old in the box if you want them. PM me

[3 pedals]

I have a 79SC 3.0L stock CIS with MSD 6AL ignition. MSD does not recommend running resistor plugs with the hi voltage ignition system. So, I tried to order the NGK BP6ES plugs to do a tune up. After checking multiple sources (including our host and every auto parts store) to find these plugs I was told they are NLA and I'd have to get the superceded plug NGK BPR6ES, whish is a resistor plug not recommended for hi-voltage ignition systems. So, I have found a source that i can purchase unlimited amounts of the correct non resistor plug for my application. If you're having the same issue maybe I can help if you need that or a different heat range non resistor plug. Thanks, Kip

[Fred Winterburn]

Yes,
They are the worst spark plugs ever and thank goodness they aren't made any more, at least I think that style is no longer made. The platinum is flush with the insulator and burns away leaving a carbon core in its place. The second problem with the flush electrode is that it does not play well with waste spark systems or any ignition that does not fire negatively from the centre electrode. Expensive, crappy plugs. Fred

Originally Posted by JohnJL

I was doing some preventative maintenance to an 85 911 and found the plugs in this condition...the motor was running OK but will obviously benefit from a new set of plugs, wires , rotor and cap. I have never come across plugs in such bad shape...they are Bosch WR70P Platinum of unknown age...one pic below is next to new Bosch WR7DCs

[Fleming]

Fred what plug would you suggest for a 2ltr 160HP+ with a MSD 6AL ignition?

Thanks.

[Fred Winterburn]

Sorry, I do not own a Porsche, but I do know that old style Bosch platinum plug is a misfire waiting to happen. I would also stay away from Champion resistor spark plugs as the resistors used to be weak. Any ignition responds better with low resistance on the secondary side, but you would be best to ask the Porsche owners here what plugs they have run successfully with MSD brand CDIs. Fred

r

Originally Posted by Fleming

Fred what plug would you suggest for a 2ltr 160HP+ with a MSD 6AL ignition?

Thanks.

[ChrisBennet]

I like NGK's. My friend was a Bosch Master mechanic (and the head of the Bosch council) and he wouldn't use those "Platinum" Bosch plugs.

[proporsche]

Originally Posted by ChrisBennet

I like NGK's. My friend was a Bosch Master mechanic (and the head of the Bosch council) and he wouldn't use those "Platinum" Bosch plugs.

this^^^^^^

[Jeff Alton]

Originally Posted by ChrisBennet

I like NGK's. My friend was a Bosch Master mechanic (and the head of the Bosch council) and he wouldn't use those "Platinum" Bosch plugs.

Yes, can't recall the last bosch plug we put into a 74-89 911 aircooled motor......

They work very well in the watercooled motors, and I am sure the proper heat range Bosch plug works OK in the aircooled motors too. But not those ****ty Platinum ones...