[T3] Marigold's story

[Jim Adney]

On 28 Jun 2014 at 4:13, Daniel K. Du Vall wrote:

> 	 I would have to agree on the use in more modern cars. One thing I
> know is that when used in modern ignition systems they tend to last
> longer. I got well over 100k on a set in my 99 Chevy and could never
> get that on an older HEI system in my 77 Chevy. I tried them in my bug
> years ago and they seemed to ware much faster.  Maybe this was a fluke
> but I tend to lean on what I have observed.  I run Bosch coppers W6 or
> W7 on my air cooled and Sometimes NGK I have a set of ND Right now
> only because I had them and they were new seem to run just fine. 

Why not W8, as that's what's recommended? I'm guessing those are 
colder plugs that may not get up to the proper self cleaning temp. 
Unless you're racing or doing exclusively very high speed driving, 
colder plugs are counterproductive. I used to do this, too, until I 
learned what the heat range actually meant for a spark plug. I still 
have some Bosch W175T1s if anyone wants them. (That's the next colder 
plug from the previous Bosch numbering system. Standard was W145T1.)

Any car with a Capacitive Discharge Ignition (CDI) system will get 
long plug life. The difference is that the CDI spark is extremely 
short, so there's less time for the electrode to ablate. As a rough 
estimate, the CDI spark is about 10% as long in time, so we would 
expect to get about 10x the mileage out of them.

I'm not sure about today's standard HEI systems, whether they are 
similar or not, but I think it's a reasonable guess. Our '96 Taurus 
had a 100k service life on it's platinum plugs and I don't think I 
got around to changing them until about 120k. At that point, I'd have 
to say that they were still just fine.

I've had Bosch Platinum plugs in both standard (Kettering) ignition 
system cars and cars with CDIs. They work just fine in either one, 
but I expect to get much longer lifetime in those cars with the CDIs. 
Most of the time, I frankly don't see much difference in plugs. They 
all seem to work about the same.

BTW, it took me a LONG time to figure out what to look for to 
determine if a plug was worn out. I finally realized that there are 2 
things to look for:

1) Look at the insulator. It should be light tan. If it's brite white 
it's either too hot a plug and/or the engine is running too lean. If 
it's black, it's either too cold a plug and/or the engine is running 
too rich.

2) Look at the corners on the center electrode and the edges of the 
ground electrode. You want them to be nice and square. As the plug 
fires, those corners get ablated away and get rounded. Once you see 
those corners get "soft" it's probably time to replace the plug.

A CDI or HEI will fire those plugs long after a Kettering spark will 
no longer jump the rounded corners, so that also adds to plug life.

A few years ago I had a squareback that I had not serviced for 
several years that began to start hard even though it had one of my 
Delta CDIs. When I finally got around to looking at the plugs, the 
center electrode was fully hemispherical and mostly recessed below 
the top of the insulator. Those were standard Bosch W8ACs. That 
demonstrated how good my Delta CDIs were and how much better they 
fired than the standard ignition.

Yes, I buy, refurbish, repair, and resell the old Delta CDIs. I have 
them in all my old VWs. I've been using them since 1966 and they are 
great! I have a number of them ready to sell right now. Prices range 
from $100 to $150, depending on the model and whether it is used or 
NOS.