I have been running Autolite 36 plugs in my 312 with good results.  Napa and Autozone do not carry them but they have Autolite 46 as a cross referance.
What are you guys using.   My engine has Mumert pocket ported heads, reworked intake, a Clay Smith Cam, Hollly 600 

Thanks,
Richard

I use 46's in both of my Y's.  They seem to be ok.  One was a new rebuilt with a bigger cam, the other a stock with mileage unknown.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ