What the heck is a roller motor?

A roller motor simply means that the engine has a roller camshaft in it. The lifters have rollers on the bottom where they ride on the cam and because of this the lifters can follow a more radical camlobe design which leads to many variations of camshafts being available. One of the best things about roller cams is that cams can be made that make great power but still remain tame enough for street use with very decent economy....kind of the best of both worlds.

Any 302 HO engine from a Mustang from the 1985 carbureted version till the demise of the 302 is a "roller motor". The blocks these engines use are unique in that the lifter valley and cam area are different to make room for the large base circle roller camshafts and the special lifters. You can have a hydraulic roller in an older block if you use one of the many available retrofit roller camshaft kits from all the manufacturers. These cams are a little different in that they have a small base circle to fit the early blocks and special lifters usually that differ from the stock roller lifters. The only downside to the retrofit its is the limit in cam profiles due to the small base circle and they are rather expensive.

If you want a roller engine then the easiest is to find a core at the salvage yard to base your rebuild on and use it with all the early modle accessories if you plan on staying carbureted.

The cam gallery isn't enlarged to make room for a bigger cam, only the lifter bores are taller to contain the taller lifters. The std base circle roller cams will work in non roller blocks with shorter link bar lifters available from Crane. These are pricey at around $400 a set. But the cams they work with are cheaper than custom ground reduced base circle cams that would be necessary to use the stock OE type roller lifters.