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FE Power Forums => FE Technical Forum => Topic started by: Joe M on August 30, 2015, 09:03:53 AM

Title: Rocker arm, valve stem alignment
Post by: Joe M 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.

Title: Re: Rocker arm, valve stem alignment
Post by: machoneman on August 30, 2015, 10:48:00 AM

Need to see a few pics!

Title: Re: Rocker arm, valve stem alignment
Post by: jayb 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...

Title: Re: Rocker arm, valve stem alignment
Post by: C6AE 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.

Title: Re: Rocker arm, valve stem alignment
Post by: Barry_R 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.