Edelbrock heads possible rocker shaft thread issue.

[Keith Stevens]

I have ARP rocker shaft studs and when I reassembled the valvetrain I noticed when I torqued it to spec if felt a little mushy. I drove the car a few miles today and I noticed the driver's side seems to have some clatter now. Has anyone had an ARP stud stretch to a point it won't meet torque spec?
If that isn't the issue the worst case scenario would be the two to the rear are pulling the threads.
Is there a repair that can be done on the engine that is sufficient strength wise?

[WConley]

Keith -  I'm pretty sure you've pulled the threads out.  Won't be the first time that's happened to Edelbrock heads...

The best fix is Time-Serts.   https://www.timesert.com/

The downside is that you really need to drill and tap square to the rocker pad.  This is best done off the vehicle.

[cammerfe]

I'm, personally, a Keensert fan. I like the locking approach. I second it that it's best done with the head mounted in such a way that the machining for the insert goes in at 90 degrees to the pad surface.

KS

[Nightmist66]

I'm using these thread inserts from McMaster Carr in my Ed heads. I have the "extra thick wall" in mine. I am running a solid roller with around 700lbs open. Part # 90246A031 is what I used. They are 3/8-16 ID × 5/8-11 OD. You may get by just fine with the thinner ones. I had my local machinist install them. He did an excellent job keeping c-c distance, perpendicular, and did not break through the bottom of the holes, so no sealer needed on the threads of the studs. I also bought the appropriate plug and bottoming tap, and the installation tool for these inserts.

https://www.mcmaster.com/threaded-inserts/black-phosphate-steel-easy-to-install-thread-locking-inserts/

[plovett]

I'm using these thread inserts from McMaster Carr in my Ed heads. I have the "extra thick wall" in mine. I am running a solid roller with around 700lbs open. Part # 90246A031 is what I used. They are 3/8-16 ID × 5/8-11 OD. You may get by just fine with the thinner ones. I had my local machinist install them. He did an excellent job keeping c-c distance, perpendicular, and did not break through the bottom of the holes, so no sealer needed on the threads of the studs. I also bought the appropriate plug and bottoming tap, and the installation tool for these inserts.

https://www.mcmaster.com/threaded-inserts/black-phosphate-steel-easy-to-install-thread-locking-inserts/

That's a good amount of spring pressure.  You have the 4 fastener mounting setup for the rocker stand on each head?  Those inserts seem to work good.

pl

[Nightmist66]

You have the 4 fastener mounting setup for the rocker stand on each head?  Those inserts seem to work good.

Yes and yes.

[jayb]

I also like the ones that Jared uses, they are also known as EZ-Loks.  Those are the inserts I'm using in my new cylinder heads.  I've broken Timeserts before, so I don't like to use those.  Never had a problem with EZ-Loks.

As far as installation on the vehicle, it can be done if you build a simple jig out of a spare rocker shaft and stands.  Set it up so that three of the stands are installed, and the one where you need to drill and tap the hole is not.  Use the hole in the rocker shaft as a guide to keep the drill aligned with the hole you are fixing.  Cover everything around it up with tape or rags or something, so that you don't get chips everywhere in the motor.  I've done a few that way, always seems to work out OK.  Not as good as removing the head, of course, but it will get you back on the road quickly.

[blykins]

Sometimes it's a heat treat issue.

For you guys who are using the traditional 4-stud mounting method and are running lots of spring pressure, how are you keeping the stands from moving around and fretting the heads?  I've used various stands/studs on cast iron cylinder heads with a lot of spring pressure and upon freshen-up/disassembly, I've always seen where the stands have been moving around.  Some of them get pretty bad, leaving transfer marks on the heads. 

On my 352 that I just dyno'd, it had billet aluminum stands with studs.  With 680 lbs of open pressure, my one-piece stand shims were noticeably marred up from where the stands had been moving around.  I've got a set of T&D race rockers on the way for my C6 heads but thought about the thread inserts.

[jayb]

I think with the 4 stud mounting system and lots of spring pressure, you just live with the fretting    I've seen that too, with 600 pounds open.

[blykins]

I think with the 4 stud mounting system and lots of spring pressure, you just live with the fretting    I've seen that too, with 600 pounds open.

I've ran 650-680 lbs open several times with cast iron heads and that's typically the end result. 

I just wonder if it will eventually stress the shaft. 

[blykins]

I think with the 4 stud mounting system and lots of spring pressure, you just live with the fretting    I've seen that too, with 600 pounds open.

Maybe we can grease up the bottoms of the stands so that it slides around easier.....   

[WConley]

Cool trick with the rocker shaft holes, Jay! 

I've never had problems with Timeserts, but I've mostly used them on industrial equipment and test fixtures.  I have also used the McMaster-Carr locking ones with good results.  Any of those solid sleeve inserts will be WAY better then Helicoils.

[Nightmist66]

For you guys who are using the traditional 4-stud mounting method and are running lots of spring pressure, how are you keeping the stands from moving around and fretting the heads?

Tolerance. I had some custom stands machined for my Erson's. The holes were finish reamed to 3/8". It is about as precise a fit as you can get. It is impossible to slide the rocker assy. down with the studs already in the head, so I have them already through the shafts/stands and drop the whole assy. down and carefully start them. i just pulled them off a couple weeks ago as part of the hibernation process. I saw no evidence of fretting. I have put around 500mi on them now. 7500rpm every time it gets out.

[blykins]

I have thought about pinning the stands but I think the studs are still going to deflect under load.   That's why the paired rocker systems are so nice, nothing is allowed to move around and everything is held to the head with a head bolt.

[drdano]

I also like the ones that Jared uses, they are also known as EZ-Loks.  Those are the inserts I'm using in my new cylinder heads.  I've broken Timeserts before, so I don't like to use those.  Never had a problem with EZ-Loks.

Similar variant I've come to like is 'keen-sert'.  It's like a full thread insert that has four stakes.  I've yet to have one fail on me.