Just got a wild though through my head a minute ago, just for kicks and giggles.

I am building a 414 magnum headed monster for the car, but I have another 273 2bbl cam/lifters and closed chamber 318 heads and thought it would be interesting to see how different the MPG would be with the same basic top end as before but another 91 cubes

I could throw the MPG top end on for a little while before I put the big cam and magnum heads on just for an experiment