Contour Enthusiasts Group Archives Forums Modifications General Mods Bosch platinum+4 observations

I just changed out my spark plugs today. I installed Autolite APP764 plugs (I guess I'll have change my signature now).

As I pulled my old plugs (Bosch Platinum +4) I inspected them as I alway do when I change my spark plugs. [The plugs were in for approximately 1 year and 20K miles.} I noticed a couple of things that I will share with this forum.

The plugs that were in the front bank looked like the center electrode had grown. It appeared to stick out of the insulator by about .025". The plugs that were in the rear bank did not have this appearance. All plugs had a flush center electrode when they were installed. [My old '85 VW GTI had platinum plugs for a while. When those plugs wore the center electrode became recessed into the insulator.] The insulators on all six of the plugs looked to be the same size (it didn't appear to that the insulator was wearing on the front bank plugs). Maybe the extended electdode was some strange sort of 'plating' that was occurring.

The plugs that were installed in the rear bank were significantly tighter (more difficult to break loose). I installed the set of plugs and I feel confident in saying that I tightened them all pretty much the same.

Anyway, enough of my rambling. Anybody have any comments?


Mike

That's why you get double plats. The banks are opposite firing. Terry?

What are you gapping the new ones at? I'm running +4's right now with a Jacob's and I'm not too thrilled with them.

One bank 'ground' on the center electrode the other on the 'ground' part of the plug and yes thats why you must use double plats ,its a polarity thing.Gapping is overrated, most plugs are pre gapped by the factory and are within specs, on a 4 ground plug its impossible to adjust the ground strap correctly,race teams etc NEVER bend the ground straps, it can cause cracks and failure in use....

You don't gap +4's.

I know that, that's why I wanted to know what other people recommended and what mbesket thinks of his new ones. Thanks though for schooling a "newbie." (New here, not to modding cars, used to do the "dime-a-dozen five-oh band wagon.)

any spark plug with the name bosch is just crap. use only the double plat spark plugs that ford recommends. they will last much longer with no randum missfires.

Really? I've had a lot of luck w/ Bosch, up until now, I guess. I picked mine up at Pep Boys (I know, I know) and that was all they offered for the Contour.

OK, here's the deal. When I checked the plugs out of the box, I was disappointed to find that the gaps were not consistant. So, I set them all to .050" (the spec is .054", but my gauge only had .050" and .060"). I was disappointed because in the last 8-10 years, I have rarely had to set the gap on new spark plugs. Oh well, that's life I guess.

I have mixed results with Bosch plugs in the past, but i thought I would give them a try anyway. [I change spark plugs once a year on all of my cars, regardless of mileage. It works for me.] I have had good luck with Autolite and Motorcraft plugs in the past. The double plats was a no-brainer for me. I have also had good experiences with NGK plugs but they were too expensive for me to try their premium plug this year. Maybe I'll try them next year.

I have had horrible experience with Champion spark plugs (side electrode crumbled after 10K miles on an un-modified engine). I will only use Champion spark plugs on things like my lawn mower, when I can't get anything else.

BTW, the car runs slightly smoother now (it's not a big difference though).

Oh, I already changed my sig.

Mike

Oops! I forgot to ask...does anybody have any idea why the rear bank plugs were tighter?

How about my guess about the center electrodes "growing"?

Thanks

Mike