i have a 74 duster i was wondering if i could change it over or not if i can what do i need to do that

Uh, why? Adjusting the valves every 30k miles too much for you?

The factory hydraulic valve gear works, but it's not very elegant. Instead of the lifters being fed oil from a galley the oil travels from the rear cam bearing, up to the head, through the rocker shaft, into the rocker arms, then down through the pushrods and into the lifters. As the lifters get their oil from the pushrods they are unique and that means expensive. The mechanical valve gear on a stock engine is low maintenance and if you already own it and it's in decent shape, quite inexpensive.

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Joshua