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Rocker Coming loose

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Old 03-18-2017, 10:31 AM   #1
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Default Rocker Coming loose

So i have finally completed my H/C upgrade. Cam 224r 600/600 112, heads are 243 milled 0.030. im running hardened PR @7.4 length and stock rockers. everything is torqued to spec and for some reason a couple rockers loosen up after a little bit of driving. only to work and home and to the shop, no high rpm runs. was curious if maybe my PR are a hair too long causing them to loosen up. If anybody can shed some insight i would be very greatful.
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Old 03-18-2017, 12:44 PM   #2
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yes too long of a push rod can cause your rocker bolts to loosen, or more likely provide false torque reading when you initially tighten them down.

there is a good sticky on checking PR length.
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Old 03-18-2017, 01:36 PM   #3
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When you torque them are you rolling the motor a few times and rechecking them? I noticed that mine moved a touch more after rolling it a couple times. Could try blue loctite if the length isn't an issue
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Old 03-18-2017, 01:56 PM   #4
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i dont have a PR length checker..but i see ill be investing in one...
RollinSS: ill be doing that this weekend coming up when im off and hopefully that does it...if not new PR's it is...

thanks for your input fellas i do appreciate it
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Old 03-18-2017, 02:55 PM   #5
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If the push rods were too long, you would probably bind the springs and bend the push rods or pull the rocker bolts out of the heads (or any combination and it would have happened already). Clean the rocker bolt holes very well and vacuum out any debris. Clean the rocker arm bolts very well and apply Blue Loctite (it will not hold if there is oil on the bolt or in the hole); torque them to 24 ft lbs. (2 ft lbs over in case your torque wrench is not perfect). Crank the engine over with the main coil plugs disconnected like RollinSS says, (they will be off because the coil brackets and covers will be removed on each side; unless you have remote/relocated coils or fancy) and go over all of the bolts again to 24 ft lbs . Put the covers and coil brackets back on again and let the Loctite set-up for a while if possible.
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Old 03-18-2017, 03:36 PM   #6
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nice step by step Jontall, i will def be doing of these steps when i get her all apart and start on it this this coming weekend. I appreciate that
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Old 03-19-2017, 07:22 AM   #7
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Follow the GM procedure. If you tighten all the bolts and then roll the motor and tighten again you need to overcome static friction and you will get false readings, i.e., the wrench will tell you they are at 22 lb-ft even though the actual preload in the bolt (stretch) is below requirements. Also, Loctite is also a lubricant and will provide more bolt stretch than dry so I wouldn't increase the torque wrench value and use Loctite, you could break a bolt. You are actually supposed to decrease the torque value if a lubricant is used. If you don't have the GM procedure I will post it but I have posted is several times in the past so you can probably find it with a search.
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Old 03-20-2017, 01:26 PM   #8
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If you want to be technical about it:
•Rotate the crankshaft until number one piston is at top dead center of compression stroke.
In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position. The camshaft and crankshaft sprocket alignment marks will be in the 12 o'clock positions. If viewing from the rear of the engine, the additional crankshaft pilot hole, non-threaded, will be in the 10:30 position. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3. Cylinders 1, 3, 5 and 7 are left bank. Cylinders 2, 4, 6, and 8 are right bank.
Notice

Refer to Fastener Notice in Cautions and Notices.
•With the engine in the number one firing position, tighten the following valve rocker arm bolts:
Tighten ◦Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 Nm (22 lb ft).
◦Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 Nm (22 lb ft).
•Rotate the crankshaft 360 degrees.
•Tighten the following valve rocker arm bolts:
Tighten ◦Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 Nm (22 lb ft).
◦Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 Nm (22 lb ft).
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Old 03-20-2017, 03:01 PM   #9
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I'm running the same cam and 243's. My 243's are milled .025 and sealed with .040 cometics. I'm running .050 preload with 7.3 pushrods. I suspect your pushrods are much to long.
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Old 03-22-2017, 12:37 PM   #10
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second that.
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