[Jim Vander Wal]

I don't think there is an absolute proper dimension for the fore/aft location. I'd consider what you want it to do. What you'll use for headers. Where it gives you the front/rear balance you want. Available space in the engine compartment. Certainly there are more variables to consider.

All references are based on the 351W. Using the sidepipe cutouts (not an absolute themselves but a starting point) a Superformance car locates cylinder 6 (one back from the front) in line with the cutout. A Factory five car moves the engine back so that cylinder 5 lines up with the cutouts.

A friends Backdraft is located similar to the Factory Five but I didn't look at the pipes when I saw it last night. Another friend's car places cylinder 7 mostly in line with the cutout but this is a long wheelbase car.

Note: these aren't exact measurements but used to show differences.

Hope this helps rather than confuses.

Jim