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Author Topic:   Breaking Rocker Arms
labman
Member
posted July 01, 2002 03:54 PM
I have a 350 Olds in a street stock, flat tops .496int/.520exh lift hydraulic cam
new valve springs 125# seat pressure, car
runs 6200 rpms the problem is we keep breaking rocker arms the motor runs good but we cant make it through the whole night without breaking a rocker arm always the same it splits apart right where the push rod seats, anyone have any ideas?


monteregal7
Member
posted July 01, 2002 05:33 PM
YES, here's your checklist.
(we've had this problem)
Make sure the springs will work at the cam lift.
Are the rockers new?
If these are OK then you will find the problem in the valve guides. When they heat up, the valves guides will tighten up. Usually galding them.


labman
Member
posted July 01, 2002 10:03 PM
quote:
Originally posted by labman:
I have a 350 Olds in a street stock, flat tops .496int/.520exh lift hydraulic cam
new valve springs 125# seat pressure, car
runs 6200 rpms the problem is we keep breaking rocker arms the motor runs good but we cant make it through the whole night without breaking a rocker arm always the same it splits apart right where the push rod seats, anyone have any ideas?


The springs specs say that they are good up to .720 lift what do you do if the guides are too tight?


monteregal7
Member
posted July 01, 2002 10:40 PM
Well, if that's the problem, you have to take your valves out and ream the guides a little bigger. Might even have to replace some valves, if they are galded.


fastrack1
Member
posted July 04, 2002 06:36 AM
ok if u have ***** in studs it is very possible that they are not in the correct position take all them off and put a straight edge on them it does nt take much to make one have the problem u have if it is not centered properly especially if it is the same ones therfore u can go to a different rocker or modify them


Brad haddix
Member
posted July 04, 2002 07:21 AM
are you breaking the same one(s) every time? are the rocker arm slots long enough?


autoshop
Member
posted July 05, 2002 09:31 AM
Also with that kind of lift and depending on weather your using 1.5 or 1.6 rocker arms you need to check the slots in the heads for push rod clearance normally in your situation the slots have to be elongated to accomadate the extra lift and rocker arm geometry. If not the pushrod will hit at end and will bind at max lift which could also cause you to be breaking rocker arms. Not to mention bend or break pushrods depending on the severity.


gahainsey
Member
posted July 12, 2002 07:16 AM
Used rockers can be a problem because they wear at the ball/seat area for 100,000 miles at .410 lift. When you install a high lift cam the ball contacts the onworn section of the rocker. This causes a point loading right at the un-worn spot causing the rocker to split. New rockers should be considered mandatory equipment when adding cam lift.


notlast
Member
posted July 12, 2002 11:07 AM
Try www.realoldspower.com They seem to be mostly drag racers,but they are very helpfull when it comes to Oldsmobiles.


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