[rotorwrench]

A special puller utilizing the spark plug boss threads to pull and bolts against the studs to push. There have been several designs show up on the HAMB. Some use flat heavy plate and some use angle iron or C-chanel. Some of the modern aftermarket speed equipment heads have larger than normal bores to fit over the studs. So large in fact, that it has caused some folks to install locating pins in the decks & coresponding recesses in the heads to locate the things in proper position for torque up.