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Roller rockers |
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Smitty52
AMC Apprentice Joined: Aug/05/2008 Location: Bolton Landing Status: Offline Points: 227 |
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Posted: Jul/14/2018 at 12:21pm |
I installed an rebuilt engine that came with roller rockers. Do these get tightened down the same as the factory units? I have run the engine to break in the cam and a couple of trips down the road and back. Seem to be getting some noise from the rockers, pulled a valve cover and they all the rockers have some play in them on the stem. After loosening the allen locks I can almost spin the retaining nut by hand. I torgue it down to factory specs (19ft lbs) and the play is gone. Check it 5 minutes later and it is loose again. Lifter bleed down? So, how tight is too tight or do are they supposed to have a little lateral play at the pivot point?
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AMO#8454, AMCRC# 8066
69 Ambo coupe, 401, M12, 66 Ambo 990 Wagon, 327,PW,PB,PS,posi,AM/FM,AC 74 Jav 360 auto ac 2003 FLHTCI, 1977 Yamaha XS750 2015 Chry 200, 2006 Pacifica |
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BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1713 |
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You don't torque to factory specs with roller rockers. You tighten the nut one by one making sure the lifter is on the base circle of the cam. An easy way to do this is "exhaust opening - intake closing" where you adjust the intake valve when the exhaust valve is starting to open and adjust the exhaust valve when the intake valve is starting to close. Tighten while spinning the pushrod between your thumb and finger. When you get all the lash (looseness) out of the rocker you will fell the drag on the pushrod. This is "zero lash". I usually run performance hydraulic at zero lash but typical stockish cam can have some hydraulic lifter pre-load if you want it quiet. So once you get to zero lash, tighten the nut an additional 1/2 turn. Then hold the nut with a wrench and tighten the allen "set" screw tightly. yeah, sometimes seems like you need 3 hands. Good luck
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Smitty52
AMC Apprentice Joined: Aug/05/2008 Location: Bolton Landing Status: Offline Points: 227 |
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OK, there is a video on Utube that basically does the same thing you describe. Maybe I am too dense (high possible) but the rocker is full up, spin the pushrod and tighten. Go back a few minutes later and it is loose again. Normal process? repeat until it does not loosen up? New cam and lifter so I don't think they will bleed down that quick. Thoughts? Thanks
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AMO#8454, AMCRC# 8066
69 Ambo coupe, 401, M12, 66 Ambo 990 Wagon, 327,PW,PB,PS,posi,AM/FM,AC 74 Jav 360 auto ac 2003 FLHTCI, 1977 Yamaha XS750 2015 Chry 200, 2006 Pacifica |
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akimmet
AMC Nut Joined: Aug/02/2012 Location: Republic OH Status: Offline Points: 428 |
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DO NOT repeat until everything stays tight, by then your valves will be hanging open.
The lifters bleeding down and the rockers feeling a little loose again is normal. I prefer to feel for vertical play instead of spinning the push-rod when setting lifter pre-load. I find it can be difficult to feel for the proper amount of drag using the spin method. |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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The rockers may move left and right but shouldn’t really move up and down once the preload is set. They will bleed down under high load, like if the valve is open. Once they have bled down they will move up and down, but shouldn’t be loose.
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69 ambassador 390
Supporter of TheAMCForum Joined: Nov/22/2009 Location: Peoria, AZ Status: Offline Points: 3539 |
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Check the pushrods for wear. The crappy replacement pushrods available out there have a nasty habit of burning the ends off and getting loose. I have had many pushrods fail at the top when using good roller rockers with hard cups. I have never had a problem with Trick Fkow pushrods, but Crane and CompCams ones have failed as well as most rebuilder sold pushrods I have tried. Check yours before going any further. Also check that you have quality rocker studs that are machined on top and not left rough. The cheap ones have rough tops and don't hold the lock very well when set. Another more ominous issue would be bad lifters wearing through the bottom,( Summit brand), or the cam going flat.
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Steve Brown
Algonac, Mi. 69 Ambassador sst 390 84 Grand Wagoneer 69 Cougar XR7 65 Fairlaine 500XL 79 F-350 Super Camper Special |
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