Continuation of the rocker arm follies

[midnight sun]

After considering everyones input and visiting two old guys here who are suppose to be sbc guru's, the consensus of opinion is that the rocker arms were not of the best material.  One of the guys said it looked to him like they were stamped cold.  He also thought the dimple where the push rod sits looked especially suspect.  Spring pressure was around 110 lbs and there was no coil bind and the rockers were not hitting the studs.  Length didnt seem to be a concern to them either.  Anyway I ordered a set of crane roller rockers.

In the meantime I decided to chase the threads on all of the rocker studs.  They are 3/8x24nf (at least all indiciations point to that!!!).  Pulled out my handy dandy tap and die set and went to work.  A 1" socket fits the die so I started down the first stud.  I lubed it with STP/Oil combo and put a small rag around the stud to keep anything from falling into unknown places.  Had a lillte resistance but not much.  When I pulled the die off I found that it had shaved the threads quite a bit.  I thought I had used the wrong die but I didnt.  I ran a 3/8 nut down some of the other studs and it was fine.  I ran it down the stud I had chased and there was definitely some play in the nut where there was none on the others.  I am now worried that over time it may pull the threads.  Im also stumped as to what happenned.  I know I can go to screw in studs but didnt t really want to go there.

Ideas/Theories/Advice?

Thanks and TIA

[40 Chev]

You can try a metric nut, but personnally I would get out the stud extractor and replace at least that one if not all studs. I would also torque the rocker to spec. I spent 3 days fixing up another guys mess because someone over tightened a rocker bolt and broke it off and then broke an easy out off in the stub.

[Pope Downunder]

After considering everyones input and visiting two old guys here who are suppose to be sbc guru's, the consensus of opinion is that the rocker arms were not of the best material.  One of the guys said it looked to him like they were stamped cold.  He also thought the dimple where the push rod sits looked especially suspect.  Spring pressure was around 110 lbs and there was no coil bind and the rockers were not hitting the studs.  Length didnt seem to be a concern to them either.  Anyway I ordered a set of crane roller rockers.

In the meantime I decided to chase the threads on all of the rocker studs.  They are 3/8x24nf (at least all indiciations point to that!!!).  Pulled out my handy dandy tap and die set and went to work.  A 1" socket fits the die so I started down the first stud.  I lubed it with STP/Oil combo and put a small rag around the stud to keep anything from falling into unknown places.  Had a lillte resistance but not much.  When I pulled the die off I found that it had shaved the threads quite a bit.  I thought I had used the wrong die but I didnt.  I ran a 3/8 nut down some of the other studs and it was fine.  I ran it down the stud I had chased and there was definitely some play in the nut where there was none on the others.  I am now worried that over time it may pull the threads.  Im also stumped as to what happenned.  I know I can go to screw in studs but didnt t really want to go there.

Ideas/Theories/Advice?

Thanks and TIA

Possibly the button die was over-tightened in the holder.  That will reduce the OD slightly like that.  Better to use a thread-chasing nut.

If it isn't too bad, I'd fit a new rocker nut, and possibly lock a half nut down on top after it is adjusted.  If it is really loose, you have no choice but to put in a screw-in stud.

[midnight sun]

Actually I didnt use the holder and that may have been where I screwed up.  I started the die by hand and then used the socket over the top of it.  I suppose its possible it was wobbling around a little and that caused the problem.  Im glad you mentioned using a jam nut.  I had considered doing that but wasnt sure.  I agree also that if that wont do it I dont have much choice but to go to screw in studs.

Thanks for your input.

[enjenjo]

Don't know if they are still available, but NAPA used the have screw in studs with no shoulder/nut on them, that would directly replace the pressed in stud with no machine work. Just tap the hole, and screw it in with locktite on it.

[Jokester]

I once bought a stud pinning kit.  It was just a little jig and a 5/32 drill bit and a box of roll pins.  Drill through the boss and the stud and hammer a pin through the hole.  Cheap and easy.

The screw ins that Frank mentioned with no jamb nut are not my favorite solution.  You have to glue them in pretty tight to get them to stay put. (loctite).

my 2 cents.


.bjb

[enjenjo]

Not my favorite solution either, but for just one stud, you can do it without pulling the head. Never had much luck replacing pressed in studs with another pressed in stud. And as for pinning them, that's a one time fix, if you ever break one, it's EDM time getting it out. If you are going to pull them to pin the studs, you might as well have them machined for screw  in studs.