Loose Rocker Arm - Team Camaro Tech
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post #1 of 9 (permalink) Old Mar 31st, 08, 01:52 PM Thread Starter
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Loose Rocker Arm

Any ideas to to why after a 50 mile run one of my rocker arms (intake) came loose? On my small block car, the rocker arm came loose after a 25 mile drive with the engine running at a constant 3000-3500 RPM.

This is not the first time this has occurred. I have had to re-adjust this same rocker several times now over the past few weeks. The adjusment is further down the the rocker stud than on the other valves. I'm afraid I might be experiencing cam lobe going flat.

The motor came with the car and has a very lopey idle 10hg or so due to the cam. So far, it has about 2200 miles on it. 1500 by me. The problem starting about 3 weeks ago.

Any help/ideas would be appreciated. I'm not opposed to pulling the cam but I just got the car running great after a Edelbrock RPM Air-gap 2*4 installation and was hoping to putt around until I get a new BB installed this summer.

Larry

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post #2 of 9 (permalink) Old Mar 31st, 08, 02:05 PM
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Re: Loose Rocker Arm

Well if you have hydraulic lifter, you could have just a calapsed lifter ( Bad lifter )..Hopefully not a bent push rod..

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post #3 of 9 (permalink) Old Mar 31st, 08, 02:08 PM
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Re: Loose Rocker Arm

Are they pressed in rocker studs? It may be pulling the stud out.

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post #4 of 9 (permalink) Old Mar 31st, 08, 02:16 PM
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Re: Loose Rocker Arm

Check to see if the rocker has a cracked down the middle of it...

Check the ball under the rocker and make sure its evan there (goes over the stud then the rocker)..

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post #5 of 9 (permalink) Old Mar 31st, 08, 02:20 PM
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Re: Loose Rocker Arm

The rocker arm nuts have worn threads.....Poly locks will cure this prob.
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post #6 of 9 (permalink) Old Mar 31st, 08, 02:30 PM
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Re: Loose Rocker Arm

If that nut is further down the stud threads than all the others, I doubt it's just a nut working loose on it's own.

It could be a stud pulling out tho.

The first thing I'd do is measure and compare the lift on that valve to one of the others.
If you don't have a dial indicator, you can just use a small machinists rule, measure from the head surface to the retainer. Hopefully you get the same measurement on that valve and a good one.





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post #7 of 9 (permalink) Old Mar 31st, 08, 02:40 PM
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Re: Loose Rocker Arm

Larry, long time no see.

It sounds like you're losing that cam lobe.

Jim's suggestion about measuring lift is a good idea.

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post #8 of 9 (permalink) Old Mar 31st, 08, 04:08 PM
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Re: Loose Rocker Arm

If you don't notice something obvious like a very loose fitting Rocker nut or split Rocker Arm , I would test the lobe profile using a Dial Indicator and compare to another.

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post #9 of 9 (permalink) Old Mar 31st, 08, 09:18 PM Thread Starter
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Re: Loose Rocker Arm

To Everyone:

Thanks for the input. The ideas are great starting points for me to investigate. At this stage, I may be running into a cam lobe going south. The rocker arm looked OK and no bent push rod. I did have a tick-tick sound every now and then upon start-up after week or so sitting.

BTW: The heads are late model GM Fastburns w/screw-in rocker studs.

I may check the lift on of cam with a dial indicator but it is not looking too promising. This is a total bummer if the cam is bad.

I will fill everyone in on the final diagnosis just as soon as I can get to the car this coming weekend.


Regards,

Larry

69 Camaro Sallee Chev. 630hp/502, Martz sub-frame, Tremec, Moser 12 bolt.
2nd 69 Camaro Soon to be a Lewis Racing 540ci Motor currently being built.
C5 Corvette
2004 MDX
2001 Honda Accord
1999 GMC Truck
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