General GM Chat When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made. Chat about all things GM (and related cars). Off-topic stuff should be in the Lounge, and all Model specific mechanical problems should be posted in the proper forum.

rocker options for cad 4.9

Thread Tools
 
Search this Thread
 
Old Aug 17, 2015 | 11:00 PM
  #1  
ehall's Avatar
Thread Starter
Member
Posts like a V-Tak
 
Joined: Dec 2014
Posts: 45
Likes: 0
ehall is on a distinguished road
Default rocker options for cad 4.9

Tried to post in performance but locked out. The Cadillac 4.9 has stamped steel rockers bolted to an aluminum support bar, with aluminum pivot/bridge holding each pair together. At high RPM the steel bolts rip out of the support bar holes (fixable with helicoils), and over time the rotational stress also causes the aluminum pivot to snap. Both are very common failures when the engine is pushed. I bought new supports and pivots when I swapped engines, and broke one of the new pivots a few weeks ago less than 5k miles later.





I am trying to come up with some options for stronger pivots. There is nothing aftermarket for these engines so I may need to adapt something, or change to a different style. 1.6:1 ratio not terribly uncommon

Sealed Power has these old rockers that look very similar except a 2-piece pivot and bridge, but the bridge is straight instead of off-set. If I could find/make off-set bridges maybe that would work



This 4.9 build in a Fiero used some pedestal mounted roller rockers, but he machined the support bar to keep them from twisting. Old thread and the OP sold the car to somebody else so can't ask about it.



I was looking at some roller rockers with a center bar and it looks like the box stand could be bolted into the support bar



Comp Cams has a few designs, same hurdles as the above, need to stop them from twisting somehow

Any ideas?
Attached Thumbnails rocker options for cad 4.9-2015_rear_rockers.sized.jpg   rocker options for cad 4.9-2015_broken_rocker_guide.sized.jpg   rocker options for cad 4.9-_571_zpsuilurfw0.jpg   rocker options for cad 4.9-dcp01895_zps2wjsxrof.jpg   rocker options for cad 4.9-box_stand.jpg  

Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
randy1962
Cadillac
1
Sep 16, 2012 08:32 PM
streetfreak
1992-1999
1
Apr 8, 2009 07:02 AM
corvettecrazy
Lounge
16
Feb 20, 2006 11:14 AM
Logan
General GM Chat
25
Dec 20, 2005 08:48 AM




All times are GMT -4. The time now is 04:19 PM.