What is the Best Nailhead Engine for You?
There are many different size Nailhead's, there are pro's and con's and we will go over most them. The 401-425's are 3/4" wider than the 264-322's and 3/8" wider than the 364. The 264-322 is about a 1/4 shorter than the 364-401-425. They are pretty close in size but as the engines got larger, the decks got taller and the engines wider. Even though the 364-401-425 is wider, it's not at the bell housing, the 264-322 1" wider there. The 401-425 engines weigh about 620 lbs. The 401 and 425 have the most power but also harder to keep as cool as the 264-322-364. If building an early car with a small radiator and closed hood the smaller engines run the coolest and the best choice. The 264 is a great engine for a light weight car, the 425 is going to give the most torque for heavy cars and trucks and for towing. The 364-401-425 have new flywheels and bell housings available, the 264-322 have only used available. Chevy automatic transmission adapters are available for all Nailhead's
The 64-66 ST400 trans from a 401-425 will bolt to all 1957-1963 blocks, will not bolt to 264-322 blocks. This information should help you decide what works for best you.