Has any one seen any guides on this? I have what the stock plug gap should be for all years and engines, however I have a 351C running 11-1 compression. I just changed the spark plugs - I gapped to origianl - however I was thinking that it might be different due to the compression.

 

Higher compression requires either smaller gaps or stronger sparks...

 

I second 69mach's sentiments. The higher the compression, the more energy it takes to jump the gap. If your ignition is stock, now may be a good time to upgrade it a bit.

 

Welcome to the site. If you don't have the pertronix or MSD electronic ignition components, you might want to consider them.

 

Got Both....

I checked a high performance engine builder book last night and it said that the gap stays the same, but I want a colder plug. If you look at the Ford manuals for the standard 351C it calls out and Autolite BF42 however for the Boss 351C it calls out a BF32 and sometimes a AF42.

 

If you have the electronic ignition, you can leave the gap the same, or even open them up a bit, if you have the flame thrower coil as well.