Magnum Heads

Coyote Jack said

I've got the Crane stud kit and 1.6 roller rockers. The push rods they sent were way to short. The MP pushrods were just the right length in my case as the block had been decked. As dgc333 said, the rockers make a strange noise, but like him I could find nothing wrong. I still have the rockers in there.

Jack

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Jack, FWIW, my block was decked also (approx 0.020" was remove for zero deck on the pistons). Even with the decking the MP push rods only gave me about 0.025" of preload on the lifters with the stock stamped rockers. The size of the base circle of the cam has just as much impact on the preload as decking.

If you used the Crane rocker they may have more clearance on the bottom so they do not contact the guide plates but: Did you actually mark the tops of the stems a check the pattern? Again it may have been the Profrom rocker but with the MP length push rod the pattern started close to the center of the valve stem and the sweep was out to about 0.040" from the edge of the valve on the exhaust side. With the 7.8" long push rod the sweep was approx +/- 0.020" around 1/3 of the way in from the exhaust side of the valve stem. Starting with the adjustable push rod at the MP length the sweep would get smaller until I reached the 7.8" length and would start getting bigger again past that point.

The large sweep of the stock length push rod puts a lot of side load on the valve stem resulting in accelerated guide wear.