Technical HELP! Spinning SBC rocker stud.

So I was changing rocker arms when one stud started spinning and I can't get the nut on or off. Also looks like its come up about an 1/8 inch. Is there a way to fix this with the head on? Drill and pin?
They are junk casting heads so long term not really concerned.

 

Lots of SBC experts on here. I'm not one of them but I do remember they used to pin them before screw in studs took over. Sounds like the plan to me.

 

drilling and install a roll pin is all I can think of.

 

ok so I got the nut off by working it back n forth but the threads on the tip of the stud are messed up. The stud is also 1/8" higher than the rest.
1-so I could run a die over the threads?
2-pull the stud somehow or tap it back down?
3-tap the hole for a screw stud?

 

Put a scrap nut on the stud. Tap it back down with a hammer. Drill a hole and pin it.

 

What gimpy said.

 

What about coolant leakage?

 

No coolant in that area. I have had a few sets of studs pinned as a cheaper alternative to screw in studs. Never had any issue with it.

 

Just replace the stud they are cheap, pull the stud and knock a new one in.

Then as has been mentioned pin it, I would pin all of them if it were me. An 1/8" roll pin will work for you even a 1/16 probably but those drill bits break pretty easy.

I know you said cheap castings so not long term but for those who do not know that is also a long term solution and has been used by budget racers for as long as SBCs have been around. I actually had some pinned heads go through my garage a couple of years ago. They were on an old 301" 283 that was being raced back in the '60s. They ended up in a hotted up '65 Chevelle.

 

pound her back in and
pin it

 

A new rocker stud from NAPA is $3.87 I am a fuckin cheap bastard and I would not try and chase threads on a rocker stud for that price. Maybe if I was 20 miles from town and needed the car to get to the autoparts.

 

If I pulled the old stud I'd think about tapping it for a screw in stud. Drill and pin on the car could be tricky depending which stud and what's in the way.

 

Actually most replacement studs are oversized to make up for the metal loss when the old stud comes out. that said I have pinned several SBCs in the car over the years, it can be done and is not as bad as some of the things that we do.

 

Agree with beaner-have pinned quite a few-some in the car. Recently had a set of 57 heads that were pinned way back in the day.

 

they used to sell oversize studs ( +/- .001-002 ) and you would freeze them and then press them in and pin it as when the stud loosens up it wallows the hole in the casting

or a good excuse to buy some real heads ..

 

For what it is worth, chasing threads on high strength steel studs is not a good idea. The original threads are rolled into the steel. Sort of like forming. Thread chasers undercut the radius at the bottom of rolled threads and result in a stress riser. In a place where you really don't want one. Also the pitch dia. will now be slightly undersize. I'm with all the guys who said get a new oversize shank stud and pin it.

 

I can get a double threaded stud without the hex, can drill and tap the head and double nut to install. The challenge lies also with getting the stud out with gibbled threads......

 

Stimpy,
They still come that way. I have seen them recently as large as .003 oversized.

Rich is correct about the rolled threads and stress risers. Normally your bolt will snap where the threads meet the shank. Almost any manufactured bolt you buy has rolled threads, two reasons it makes for a more stable bolt but it also is a cheaper may to manufacture.

 

Slide hammer mentioned it on another thread about a week ago. If you can get the nut off you can get the nut back on then slip the hook on the slide hammer under the nut and bam away at it. That stud is already pulling loose so it will come put pretty easy.

 

Ok thanks guys, I have the screw in stud on the way, I'll let you know tonite the results!

 

^^ Good idea, don't listen to those old farts.

Either way should work fine. Just tap the hole straight!

 

I don't know your exact plan as to your tapping method or which style stud you ordered, that is: with or without the hex, but either way you may be creating a bigger problem if that is not tapped straight.
Just say'n.

 

was it morosos used to sell the tap guide for conversions so the stud goes in straight ?? basically its a block that slid over to the stud next to it to align the tap . one thing is how you going to surface the head were the stud bottoms out against ?? without the flat surface the stud will back out again or crack the casting from movement .

 

Yep Moroso still sells a tap guide and stud puller combination.

if the hole is relatively round, Stimpy and I both know that is not probable, a 2 or 3 flute tapered tap should go in straight pretty easy then a 4 flute bottom tap would finish up the hole really well. I have been known to take a counter sink and open up the top of the hole a little bit to make it easier to start the tap.

if the stud has a hex and is not a straight stud the top of the rocker tower needs to be milled off the compensate for the hex.

 

I learned about getting the tap straight the hard way. I tapped all of the holes for screw in studs in a SBC head without a guide. When I screwed in the studs the head looked like a porcupine. Then I got to do it over with a milling machine and bigger studs. One heck of a way to get heavy duty screw in studs. It was also very educational.

 

I have the stud in my hand now (Pioneer RM348). There is no hex. 7/16 NC thread on bottom 3/8 NF on top. It just needs to hang on for the summer. I'm fairly confident on the tapping straight. Locktite it in. Done. Burn rubber.

 

I'll just add this, as it involved a very similar situation. My folks had bought a 76 Chevrolet Blazer 4 WD new. Years later it would start "tapping" out of the blue, and it was always the #1 exhaust rocker that was loose. After a couple times readjusting it, then replacing the lock nut, I got deeper into it. It was obviously pulling the stud out, so I stacked washers under the nut and pulled the stud all the way out. Wanting a quick fix without messing around ,and spending any time or money on it, I took a cold chisel and tapped some retention marks into the stud end, slathered on some Permatex sealer, and used a brass hammer to tap the stud back in. It was't the "right" way to do it, but Mom was going to be trading the Blazer in, and it took care of the problem. The guy that eventually bought the Blazer from the dealer was a friend of my younger brother, and he never had any further problem with it either, not that he was told about the stud pulling problem. I think it was already mentioned, but they do make oversized, press in studs. I am Butch/56sedandelivery.

 

Fyi...
There IS coolant under the rocker studs on small block chevys....

 

I had a 57 Pontiac with a tired engine...it pulled a press-in stud [same setup as a SBC] and I was planning a new engine real soon. Used a socket to pull the old stud and hammered in an oversized stud from the local auto parts house. Cost me less than 5 bucks for the stud and another few bucks for a can of brake cleen and a tube of stud-setting compound. Was still in place when I replaced the old engine a few months later.

 

Permeatex PTFE Teflon paste works well to keep antifreeze where it belongs. I use to install a lot of these on the old Peterson seat & guide machine, in future if you use the stud with cast in nut, one must measure thickness "height" of that area of the stud & machine the pedestal the stud lives in down that measurement to keep correct installed height. Otherwise likely to snap studs off. Good luck sir. Flux