Interesting Spark Plug Finds--Beware of Champions?

I have been messing with my spark plugs, and decided to pull one of each and stick them into a spare head (GT40P) just to see "what's up" on the piston side of the plugs.

Found some interesting stuff.

First off, I noticed that as I bought different brands of spark plugs while trying to replace my platinum plugs with various brands of copper plugs, the thread and neck configurations looked quite different. I thought I had the wrong plugs, but when I put them in the heads, they all seated the same with a tapered neck, but the threads were varying lengths.

The Autolite had the shortest thread, then the AC Delco had a mid-depth thread, and Champion was threaded all the way up to the taper. Looking in to the head, there are only threads a short way, maybe 5-6 threads total. So the extra threads on the AC Delco and Champions are not used. You can also clearly see how many of the threads are actually being used on the Champion plug, by noting the oil on the plug threads.

More importantly to me, there is a whole extra thread on the Champions that extend into the cylinder. It seems to me that that extra thread would pick up carbon and other "stuff" and when you pull the plug out, it may have a tendency to scuff up the threads on the heads. The thread in the picture is put in by hand, and not torqued down, so there would be even more thread exposed after it was torqued.

Just FYI, and maybe we should steer clear of Champion plugs?

These are GT40 and P heads, has anyone noticed similar with stock heads?

 

ya champion plugs suck!!!. measure with a ohm meter the resistance of the pulg and champions are never consistant. a shop i used to work at would give me those for tune ups and i would send them back every time asking for autolites. also autolite makes motorcraft spark plugs so you geting the same plugs that ford uses for there cars.

 

I have heard in the past when I drove Japaneses cars to use foreign plugs, because American plugs have an extra thread. Apparently, it is not all "American" plugs.

Anyone ever see this on any other than the Champions?

I say "American" because I have no idea where all of these plugs are made. AC Delco could be Japanese for all I know...

 

interesting test , scoop ..all this info and free too! now you gotta get some ngk's to test out...thanks

 

Do you know the cross reference number to the plugs I am using? I will do it if it with any brand, just for the hell of it. As long as it isn't Accel P526S ($18 EACH!!!)

If I have the heads just sitting here, I may as well use them for something semi-productive...

And, by the way, I still have the AC Delco box on my desk..."Fabrique aux E.U."

 

for you texans ,"fabrique aux E.U. " made in the etats unis..united states..
found you a ngk part number....wasn't easy...platinum would be #sr5vx and their v power plug would be#tr5-2238...enjoy

 

What is the "regular" baseline copper NGK number, is that the tr5 one?

Don't want to buy a platinum plug that I will never use except to take a picture and post it here. Besides, my recent experience with platinum plugs on this motor is less than satisfactory...

 

Good info- thanks!

 

yeah as far as i could tell the tr5 one..

 

I used to work at an autoparts store & I can't tell you how many people would not buy Champions. If we didn't have the Autolites or Motorcraft that they were looking for, they would just go elsewhere.

 

I was told years ago by an old time Ford mechanic, to never use Champions in a Ford, and I never have. I would think that if you were indexing your plugs, the extra thread would be handy if you had to use washers?

 

Good point on indexing and using washers to take up the slack...

 

I have never had good luck with champians. I have had them work for a couple of hours and then fail to transmit a spark. We called the Champian rep and he told us to heat them with a torch and install them hot.
Well it worked but how do you tell your customers to get out their acetylene torch and heat their plugs so they will work......
I only buy Autolite. They have always given excellent service.

 

Splitfire SF42C is what I used before but they don't make them now! These were awesome in the early 351W heads!

 

I would think that the extra threads sticking into the chamber would be an excellent source for hot spots and pre-ignition ...