How tall are your rear tires? Years back a buddy and I decided to play with his 72 Demon 318. Threw on and in a bunch of left over parts and a 4.10 gear and the thing rewarded us with a mid/low 14. The car was bad dead out of the hole and kinda figured the 480 lift (unknown duration etc) Wolverine cam was retarded since Gary just lined up the dots even though I told him I had a degree wheel etc. The exhaust note was pretty loud and that can be another indicator.