Small block mileage

The less power the engine made the less % it was, the greater the power, the higher the % will be. While starting with a higher compression engine is great for hot rodding later, it isn’t a big gain and even more so on our earlier cars. Todays cars are in a different field.

Better heads or at least head flow is the key demonstration by @IQ52 AKA Jim LaRoy. On that note, it makes me wonder what the Chrysler engineers discovered when they tested the W2 heads on a 360. To bad it never was OK’d for the Little Red Express truck.

If the W2 actually flowed what the MP book and MP reported, that would have been an interesting engine to play with.

What higher compression would have delivered and quite well I think would have been a much snappier engine on he throttle.

The older 319’s were labeled at 9.0-1. I have one to take apart so maybe one day I’ll actually know when I mic it up.


It has been a while but I have had several of the early style 67-68 318's apart that had the different full floating rods and higher compression pistons. around 9 to 1 sounds right as they were much better than the run of the mill 70's/80's 318s.

A properly prepped 318 magnum with zero decked pistons and .035 or so quench would be close to ideal for mileage and would not require the use of premium fuel for regular street use. Probably wind up about 10 to 1.

@hotroddave has done several of these mileage type builds and has lots of info about them on moparts.com