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Got home last night from cruise night and rolled to the bottom of the drive way when the car stalled (again!) damn that WCFB!! All was running well until I came back out of the house to put the car in the garage. When I started the car I heard what sounded like a loud knock coming from the motor. Sounded like the bottom end. I shut the car off waited a while and started it again and the noise was still there. After choking down my dinner, I went back to the garage to pull the valve covers. First cover showed no signs of anything wrong. When I pulled the passenger side I found the number 8 exhaust rocker arm was broken in half right through the hole in the center that slips over the stud.Push rod is straight. ( whew!!! at least it wasn't a major breakdown or catastrophic failure like a rod!) I picked up a new rocker and am going to install it tonight. I need a little help with the installation. I plan on installing the rocker and doing an approximate adjustment (left a bit loose)before starting the car. I will adjust the nut with engine running to remove all lash (and the clacking noise) and then increase the adjustment another 3/4 turns (1/4 turn at a time). Does this sound ok with you guys?
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Re: broken valve rocker arm C1
make sure you put some oil on the new rocker arm at the pivot area before you start the engine.crank the engine over till the intake valve on that cylinder opens all the way,and then goes almost all the way close,set the the exhaust by spinnng the push rod between your fingers while tightening down till you feel the push rod get tight, then continue to tighten the nut 1/2 turn more. you can then start the engine and do the running set. -
Re: broken valve rocker arm C1
clem and Don-----
I've never had a lot of luck using the "spinning" test for the pushrods. It seems that you usually can still "spin" the pushrods even after the turning down of the rocker nut causes the plunger in the lifter to be depressed. I usually feel for the end of VERTICAL movement of the pushrod. When this point is reached, then I turn the rocker adjusting nut down 3/4 to 1 turn.
What I usually also do is to set the cylinder that I'm working on at TDC (of the compression stroke, of course). Then, I adjust both valves on that cylinder as described above. Clem's method will work just as well and is, essentially, the same thing as I suggest.
In most cases, I've found that adjusting hydraulic lifters as above will represent a final adjustment and no further "hot-and-running" adjustment is necessary. In fact, that's how GM adjusted them at the factory for millions of engines. No "hot-and-running" adjustment was generally performed.
One other thing: if you had a rocker arm fail like this, I think that I would check the other rocker arms for condition. You may have others about to go. While rocker arm failure in a stock Chevrolet engine is not common, the fact that one of yours failed tells me that something is going on here.In Appreciation of John HinckleyComment
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Re: You adjust valves with motor off?????? *NM*
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Re: You adjust valves with motor off??????
Don-----
Yes, with the motor at "complete rest". As I say, that's exactly how the GM engine plants did it for the MILLIONS of engines that they built. A few may have needed a follow-up adjustment at the dealer's service department, but the VAST, VAST majority never needed or received any "hot-and-running" adjustment.
Even mechanical lifters can be adjusted with the engine cold and "at rest". However, due to the much "narrower" adjustment requirement, they may need to be re-checked "hot-and-running".In Appreciation of John HinckleyComment
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Re: You adjust valves with motor off??????
So, That means I can adjust the one noisy tappet w/o getting oil over everything. How do I know exaust from intake? Don You know I am basically a plier & cresent guy who used to fix my junks on the road to Vegas!!!! Now I have to relearn... Thank youComment
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Re: You adjust valves with motor off??????
the small block valve order, E-I-I-E-E-I-I-EComment
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Re: You adjust valves with motor off??????
Don:
With the valve cover off, just look at the runners on the intake and the exhaust manifold. The valve will line up with these runners and tell you which is which. Or, the (starting at the front of the engine) first valve is exhaust, the next two are intake, the next two are exhaust, the next two are intake and the last one is exhaust.Comment
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Re:Sorry Clem its a 1967 427/ 400hp Don *NM*
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