Is the filter mounted upside down? On my Duster drag car, I use a 2-quart (GM truck) filter, which "hangs" from a Moroso bracket. I mounted it behind the R/F tire inside the fender on the side cowl panel. No drainback problem, as the -10 hoses are above the filter. It's low enough that I can just get my hand in there, but the adapter/bracket is higher in the car than the fittings in the block by several inches.