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Author Topic: Rocker arm, valve stem alignment  (Read 2930 times)

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Joe M

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Rocker arm, valve stem alignment
« on: August 30, 2015, 09:03:53 AM »
Good morning.  A friend of mine is assembling a 390.  After installing the rocker shafts, he noticed the rocker arm wasn't properly located on the valve stem top.  In fact, it was close to sliding off.  The heads are brand new Edelbrocks.  He called me as I've assembled a few FE engines but I've never had this problem.  What could be causing this?  Wrong rocker stands?  Wrong length pushrods?  He also said the engine used to break rocker arms before the rebuild.  Any ideas as to how to correct the problem?  Thank you.
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machoneman

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Re: Rocker arm, valve stem alignment
« Reply #1 on: August 30, 2015, 10:48:00 AM »
Need to see a few pics!
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Bob Maag

jayb

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Re: Rocker arm, valve stem alignment
« Reply #2 on: August 30, 2015, 12:27:11 PM »
What rocker arms is he using?  Provided they are the correct dimension, he could just be looking at moving the shaft one way or the other to get the tips lined up with the valves.  There is some slop in the rocker shaft and rocker stand holes...
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Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

C6AE

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Re: Rocker arm, valve stem alignment
« Reply #3 on: September 03, 2015, 10:53:02 AM »
It is not clear from your description in which direction the rocker is "sliding off"
It may not be a rocker shaft or push rod deal at all. If the valve guide or seat was "weird" it could place the tip of the valve in the wrong place. It's easy to check that in both planes with a straightedge.
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Barry_R

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Re: Rocker arm, valve stem alignment
« Reply #4 on: September 03, 2015, 01:02:56 PM »
Answering from home (watching the kids this week since the spouse is going to work related meetings...)...

Edelbrock heads have the exhaust valve moved .050 from stock locations.  You might need to shim the rockers over a bit to compensate.
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