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#1
04-20-2021, 12:52 PM
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Rocker Arm Adjustment Pressed in Studs
Helping a friend with a cam swap. Its a 65 Big car with original 389 having pressed in studs.
Swapped to a stock 068 cam so he can run a tri power. Soaked the lifters in oil but they are not hard. Do you tighten the pinched rocker nuts all the way down? Some say to 22ft pounds but that is all the way. Why I ask is because the pushrod is pushing the top of some of the lifters down a bit, in one case a good quarter inch yet I can still spin the pushrod with my fingers. All were set on the back of the lobe with valley cover off. Thanks. |
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#2
04-20-2021, 01:27 PM
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The 068 camshaft has basically the same camshaft lift as the 067 camshaft which should be a "P" camshaft. The 068 Camshaft should have a S stamped on the "nose" of the camshaft horizontal surface that the timing gears and retention bolt screws into.
The lifters are adjusted as you mentioned by putting on the rockers and pushrods and then snugging the rockers down and depressing the lifters. You can spin a new pushrod, or a well treated pushrod in the rocker cup even at some camshaft partial lift modes. This is because Pontiac used fairly soft valve spring seat pressures with stock type camshafts. No worries there. Gire it up for 20 minutes at 2000 rpm and break in the camshaft and lifters and enjoy the new camshaft and lifters. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
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#3
04-20-2021, 06:46 PM
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When the lifters are sitting in oil at least up to the side oil hole you need to push down on the plunger a number of times with a push rod or such to get the lifter primed.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
| The Following User Says Thank You to steve25 For This Useful Post: | ||
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#4
04-20-2021, 07:07 PM
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Tightening down to 20 lbs of torque.
GTO George |
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#5
04-20-2021, 07:46 PM
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Stock rocker nuts are not pinched!If pinched the TQ setting might not work?Tom
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#6
04-21-2021, 12:37 AM
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Careful! Stock pressed in studs have a taper on them where the adjuster nut with its own matching counter taper seats. If all
heights are correct one merely torques the nuts to 22 ft lb. and the hydraulic lifters should be fine. If you want adjustment on the rockers you need either poly locks or I suppose pinched lock nuts. In either case, when you buy a set of nuts you must be sure they are for a Pontiac and have the recess like the factory nuts. They cannot just be flat across the bottom. Way back when, I was sold Chevy Poly Locks that had no recess. You are unable to screw the nut down far enough to get adjustment. I put a breaker bar on it and turned a stud. The stud never failed or pulled out due to my verve.e |
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