That just occurred to me. Since the rebuild my car has had E7 heads and a HO cam but I've been using stock plugs. It's only now entered into my head to check the part #s on Rockauto and discover Mustangs and Tbirds don't use the same plugs. It's been a year and the car has run adequately...just what are the differences? Should I consider getting Mustang plugs...or is there some way to determine the plugs you should use based on engine configuration?
depends really, if you car had e6 heads they use a long thread plug like the GT40 heads and would protrude into the chamber,I would reccomend the corect plugs for the heads.
motorcraft awsf52c, awsf42c ,awsf32c
autolite 26,25,24
etc.. higher the number colder the plug. (on a stock car i use 26's , if it shows signs of detonation i step down to a 25 or 24. )
plugs for e6 heads will not screw into an e7 head. auto-lite 24's, is what most of the mustang guys use.
they will screw in (same thread pitch) but will not seat properly (differant reach and seat height) if my memory serves me correctly.
when i had e6 heads on my car, without thinking, i bought plugs for e7 heads. because i always used 24's. i went to the track to make some runs, and decided to change the plugs, but 24's basically just fall in the spark plug hole. no thread engagement at all.
I'm not certain my old heads were E6 actually. Tomorrow I'll go archeologist and try to find the casting #.
Okay I was curious so I went out and looked now. Was a little hard to read but I'm pretty sure the old heads # is D8OE.
yup, you done it backwards, see the threads in the e6's are farther down (hence the long threads and tall seat) when you tried to put in the short thread plug in there was no thread contact (e7 plug in e6 head). they will screw in visa versa (e6 plug in e7 head)
d8's use the same plug style as the e7's the differance is in the heat range of the plug between the heads and not the style of plug.