I am in the process of installing some Edelbrock RPM heads on my 327/350 and noticed that the plug they recommend, the Champion RC12YC, contacts the dome of the piston when turning it in. What I need is a plug like this that does not have the extended tip. I have looked all over the net trying to find a site that could tell me what Champion offers. Basically what I need is a 14mm, 3/4" reach, 5/8" hex, standard tip. Any help is appreciated.

Autolite AR3933 or NGK R5671a-8 will fit just fine.

I had the same problem and solved it by indexing the plugs. Indexing gaskets are cheap and readilly available (I used Moroso's). It's a PIA as you have to do each cyl individually but I got used to it. I used a felt tip marker to put a marke in line with the ground strap (opposite the gap). The clearance problem is only when the strap is facing the dome and I never had a problem as long as it was about 30º or more away. That meant the plugs could be installed with the strap anywhere from sideways to opposite sideways or in between (or roughly in a 270º arc). I figured that Edelbrock knew best which plugs to use with their heads so I used them. I did try equivilent AutoLites and AC's but they were slightly longer (on the outer part) and didn't fit as well with my headers.

I am using NGK B6S with my camel humps and a dome pistons.

9SecBuick:
Do you know what the numbers would be for those plugs in a non-racing, resistor plug?
Thanks.