I've posted about this before, but my car has had some weird type of hesitation that I don't recall being there before. As you are driving and holding constant (light) pressure on the gas, or if you take off from a stop slowly, it would hesitate or jump a little, and the RPM's would fluctuate around 300-400. It seemed to be getting worse lately.

Tonight, on the way home, I noticed that a lifter that was previously ticking got much louder, then started clanking & banging really hard. Before I could pull over, the banging stopped.

When I got home, I pulled the valve cover and found the nut laying in the bottom, the rocker arm sitting sideways & push rod just sitting there (this was on the intake valve for cylinder #3). My two questions:

1) If this had been getting more and more loose over time, would this explain the hesitation I've been having? I wasn't able to take the car for a ride after fixing.

2) I think this is the second time this particular rocker arm has come off - I remember that after first installing the engine, one of them came off but I can't remember if it was this one or not. If it is, what do I need to replace to stop this from happening again? The nuts that I'm using have the Allen head lock in it, I verified (again) that it's tight.

 

I'd say it could be the possible cause of your problem, and try loctite on the threads? might help it. I'm not really positive hope someone else chimes in for you, but I loctite anything I have problems with backing off

 

a self locking nut (wich rocker arm nuts are) like anything mechanical can wear out . buy a new set of GOOD nuts (not china crap) & properly reset valves . good luck .

 

If they are the stock nuts they don't last being reused forever

 

Thanks for the replies, but (1) they are basically brand new, they have less than 100 miles on them and probably a grand total of 15 hours of running and (2) I think they are decent quality, they appear to be very similar to these (though I don't know the brand):

http://www.summitracing.com/parts/cca-4601-16/overview/

In any event, it sounds like the nut is my problem (could have been bad from the factory) and most likely not the stud. I'll find out from the guy that built my engine what he used for sure and go from there.

Thanks again.

 

There's a little trick to getting those type of rocker arm nuts to stay tight. Once you get it tightened to the point where there's no clicking anymore, take your allen wrench, and your 5/8 wrench, and simultaneously tighten both together about another 1/4 turn. When they're tightened separately on the final adjustment this will cause the nut to back off eventually. In fact, you really need to go through and re-tighten all 16 nuts this way. Doing the final tightening of both together helps to actually "lock" the nut and allen setscrew the way it's supposed to do.

 

I definitely did not do that; I just each one, turned the nut a quarter turn & then tightened the allen wrench. Oops.

So...assuming my valves are adjusted correctly, can I just loosen the allen head & nut by 1/4 turn, then re-tighten? Or do I need to start over with the adjustment if I loosen them?

 

What type of rocker arm studs are you using? stock not flat top or something like ARP that are perfectly flat on top?
Those don't work well with stock rocker studs, your best bet is to use the dubble nut method. (all my old girlfriends enjoyed that also but thats another story for another time)

 

You probably don't need to back them off and totally re-adjust them. With hydraulic lifters it shouldn't hurt to turn the nut another 1/4 turn. The lifters will compensate for it. So yeah, just turn both the nut and set screw together 1/4 turn from where they're at right now and you should be good.