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1987 5.0 rocker torque or lash specs?

9511 Views 4 Replies 3 Participants Last post by  umfan92
I've been fighting a rough idle for some time now and I've gone through every possibility. I have reason to believe that the rockers have been tightened down too much, so I'm going to recheck all of them. The engine only has about 5000 miles on it since I got it rebuilt from a reputable company.

I know it has hydraulic lifters so there's not lash, but there is a lot of confusion about how to install these rockers exactly. I have heard to tighten the bolt by hand until zero lash, then another 1/2 to 3/4 turn. I have heard to just torque them to a certain number (I've heard 15, 20 and 25 ft.lbs from several different sources). I'm not sure what is correct.

They are just stock stamped pedestal rockers so nothing fancy. I'm not really looking for power. I just want a nice smooth idle.

So what is the best way to go?
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Is it even possible to over-tighten pedestal rockers to the point of running rough? I'll re-check them anyway, but I'm not sure it's even possible.
I know the torque spec for roller rockers is 20 ft. lb. The stock rockers are likely the same, but hopefully someone can confirm that (I don't have my manual in front of me). The "lash" spec for hydraulic roller engines is 0 plus 0.020-0.060 in. of preload on the lifters. In other words, after the exact point when you're tightening the rocker arm and achieve zero lash, the plunger in the lifter should get pushed in 0.020-0.060 in. This usually equates to 1/2 to 1-1/4 of a turn on the rocker arm bolt.
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Haynes says 18-25 ft lbs for the rocker arm fulcrum bolts.
When I re-adjust them, does it matter if the lifter pumps up and doesn't go back down again once I torque them again?
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