i just put the summit 1.6 ratio rocker arms on my sportsman 2's last week. It seemed to wake up the motor considerably. now my problem... I started my car up the other day and i thought it sounded funny, but i didnt think that much about it. I put it in drive and started to take off, it sounded like it wasnt running on all the cylinders. I parked it and checked it yesterday and found my rocker arm laying in my valve cover. The rocker arm stud (screw in) snapped in half. what happened??? maybe a defect?? however, i know a guy who built a few racing engines in his time and he told me to loctite the rocker arm studs in the heads because if you dont they have a tendency to work their way loose and when the work themselves loose, thats how they break. I dont know if this is true or not. the lifter seems to still be in place and i didnt bend a pushrod or anything of the sort. im debating on whether or not i should replace all of the rocker arm studs with the ARP studs. any suggestions or comments on what should be done? btw, i tightened them down to 65ft/lbs of torque. Maybe that wasnt tight enough? i dont know, any help is appreciated.

 

Did the stud break above the bolt? Was the bolt portion still tight? were you using poly locs? I've seen studs break into where someone set the lock on the poly lock (allen head) and continued tightening the nut stressing the stud.

 

the stud broke in between the nut and the pivot ball.... ?????? I had to unscrew the top of the rocker arm stud out of my nut so i didnt have to buy another.

 

im not sure what a poly lock is so, no i did not use them.

 

Check the rocker fulcrum center oval portion is there evidence of binding? Did you lube the fulcrum with moly lube on assembly? I would think something Binded.

 

i'd be checking geometry and did you have sa or non sa rockers? what did you replace them with?

 

I've had those studs break before just from removing the lock nut... one motor I was working on I had 4 break before I got all the rockers off so I back the nuts off very slowly any more when I am working on them... you may have other ones that are bombs waiting to explode on you.

 

i have the non-self aligning type. However, i have guideplates so i dont think it would matter. I will check for evidence of binding as soon as i get home from work today. i replaced the 1.5ratio rockers w/ summit 1.6 ratio rockers, the p/n escapes me right now. but i drove with them on for quite a few miles since i put them on and nothing seemed to be wrong. I would think the geometry would be ok, but i dont know. Im not exactly sure how to check the geometry, i will do a search on it later. RB83L69, i did remove the nuts rather quickly, i was sort of trying to get that portion of the project done asap. That could have something to do with it!?! I am probably going to replace all of them with ARP studs. hopefully this wont happen again.

 

It might... some of the ones that broke for me were so hot that I burned myself when I picked up the piece, and they made a loud sqeaking noise too. I back them off slowly since that happened, I don't need to be creating any more weakened parts just waiting for their chance to fail at the worst possible tme and cause me maximum grief like they always do.

 

I just replaced all my springs last Saturday and I used an air ratchet to take off the lock nuts and used it to put them back on. I had no idea or even thought of having a stud break. But I have ARP studs. Is using an air ratchet on the nuts not a good idea? I was being lazy and that seemed to work quite well. Also I set my valves with dial calipers. I set #1 the old fashon way by going up and down with the rod till it wouldn't go up and down anymore then a 1/2 turn more then I took the dial calipers and measured from the top of the nut to the top of the stud and made all the valves the same. Car ran wayyyyy better doing the valves that way. I guess getting them right makes a huge difference. Car starts easier to and has lots more power than before. I always thought that hydraulic lifters were more forgiving. I was wrong.

Brad...

 

I just had the exact ssame thing happen to me tonight.
Driving normally, stop at lights..runs on 7 cyl.
Get home, pop rocker covers off and the stud was cleanly snapped.
Heads are world S/R's been in the car 3 months...Looked to me there was a shading line right through center of bolt....almost like it hadn't been head treated correctly from factory.
Don't think its a geometry prob...factory assembled heads.
Pushrod not bent and no binding marks either.


Is it possible that the stud was just a poor quality unit right from the outset?

 

I havent had any trouble with this since I went w/ the ARP studs. I think when I changed the rocker arms to 1.6 ratio, I backed off the nut too fast like RB83L69 suggested. If I was you, I would just replace all of them with the ARP ones. they arent that expensive, and they are definetly a better quality part then what I had before. Just a suggestion.

BTW, can you say "RESURRECTION"? LOL

hope I could help.

 

I have seen this happen on 2 different SBF motors that used the Chevy style rocker studs. The problem was the studs were not long enough & the nut only bit on the top 3 or 4 thread & it snapped off right just under the nut. The solution was longer studs.

 

Think I'll replance all the studs with ARP's like you said...Thanx for the replies.