these were in my Z, Autolite Platinums, AP 3924. Im guessing these are the kind. if wrong ones are used, what symptoms are present

 

I'll post you a pic tonight of one broken exhaust valve and one bent intake valve from the last vehicle that I owned that had autolite plugs. (As in, don't use autolite plugs). I know you didn't put them in, but I'd get them outta there.

In my little incident, the center electrode fell out of the plug and after bouncing around inside the cylinder for a few seconds, it decided to exit thru the exhaust valve.

Use NGK plugs only.

 

thanks CC, much appreciated for the info. yea, i didnt put them in there. being totally unaware of what proper needs the z has to have, i had taken it over to my auto place to get maintenance done on it. it orginally had Bosch plugs, the guy said those are wrong and put in these Autolites. like $3.00 a piece.

 

hehe autolite are walmart brand plugs.
check out my sticky about spark plugs.

 

Here's the walmart (Fram Autolite) special plug. If you look closely, you can see that the center electrode is gone. The valves are from a FoMoCo special. I was pretty surprised at how the valve broke from the thin section into the thicker section instead of radially around the thin section. Actually the broken valve is the intake. The valve on the right is the exhaust that is bent. We didn't realize it was bent until re-grind.

Moral of the story......... go NGK

The custom spark plug holder in the pic is from junior #1's motorcycle engine after he went a little too long at WFO across the desert. It's kinda hard to see, but the rod big end stretched about 1/4". Again, another surprise that it didn't break. It definitely bounced the piston off the head a few times before it stopped turning over.

 

NGK period.

 

thanks guys, it seems i can get NGKs at Z1 for a 9.00 a piece

 

I think coz or courtesy might be cheaper.

 

ha, thanks man. theyre cheaper on courtesy. couldnt find them on coz.