Rocker arm studs are short.

[f_inscreenname]

Went to install my new roller rockers today. Got everything broken down and the valve covers off. Got the motor in the #1 F/P. Pull the old rockers off and put the new ones on. I thought right away that the studs were not long enough. So I twisted on a poly lock until it seated and there was 0 lash. Then counted the turns it took before it came back off. It was 1 and a ¼ turns and I could lift the lock off the stud. If you add in the ½ turn to adjust for lash that means the Poly lock will only have a turn and ¾ to hold the rocker on. That don’t seem right. Do I need longer studs or shim the studs out from the head with washers or something?
http://img234.imageshack.us/img234/4521/66yt5.jpg

[steelcomp]

Went to install my new roller rockers today. Got everything broken down and the valve covers off. Got the motor in the #1 F/P. Pull the old rockers off and put the new ones on. I thought right away that the studs were not long enough. So I twisted on a poly lock until it seated and there was 0 lash. Then counted the turns it took before it came back off. It was 1 and a ¼ turns and I could lift the lock off the stud. If you add in the ½ turn to adjust for lash that means the Poly lock will only have a turn and ¾ to hold the rocker on. That don’t seem right. Do I need longer studs or shim the studs out from the head with washers or something?
http://img234.imageshack.us/img234/4521/66yt5.jpgLooks like the trunion could be upside down.

[GofastRacer]

I'll second that!..

[vee-driven]

buy longer studs!!

[f_inscreenname]

I'll second that!..
No they are right side up. The other side does not have a seat for the poly lock.
So… I went out after the post and pulled a stud from the head and got out my caliper to see what is going on. From what I got from it was…….
1.750 - the stud is now from where it seats on the head
1.00 - is how long the poly lock is
.284 - is how far the stud will go inside the poly lock now at zero valve lash
.081 - is how much deeper the stud should go inside the poly lock when it is giving the half turn after zero
.426 - is how big the stop nut inside the poly lock is
.791 - is where the top of the stop nut inside the poly lock should be now fully installed
Now if I use 1.90 studs the stud should go .150 further inside the poly lock. Adding that to the .791from above the top of the stop nut inside the poly lock should come up to .941 of the 1.00 lock or .059 from the top.
Does that sound right?

[maddad]

You should think about spot facing the studs so the lock seats evenly.

[f_inscreenname]

You should think about spot facing the studs so the lock seats evenly.
Thanks, I read all about that in another H/B thread and will definitely do.

[Moneypitt]

Yes, longer studs, AND a GIRDLE.......The posi locks are un necesary when using a girdle, so the longer studs don't need to be faced........MP

[GofastRacer]

No they are right side up. The other side does not have a seat for the poly lock.
SoÂ… I went out after the post and pulled a stud from the head and got out my caliper to see what is going on. From what I got from it wasÂ…Â….
1.750 - the stud is now from where it seats on the head
1.00 - is how long the poly lock is
.284 - is how far the stud will go inside the poly lock now at zero valve lash
.081 - is how much deeper the stud should go inside the poly lock when it is giving the half turn after zero
.426 - is how big the stop nut inside the poly lock is
.791 - is where the top of the stop nut inside the poly lock should be now fully installed
Now if I use 1.90 studs the stud should go .150 further inside the poly lock. Adding that to the .791from above the top of the stop nut inside the poly lock should come up to .941 of the 1.00 lock or .059 from the top.
Does that sound right?
Hmmm, from the pic it sure looks upside down, but if it's right then a longer stud is needed, and I gotta go along with MP, use a stud girdle!..

[vee-driven]

they are right side up, thats the groove the poly lock will seat into, others are flat on top, and they are round on the bottom.

[Moneypitt]

Looking at the pic again, those are aftermarket studs. The "shank" area is under cut, and the tops are different than GM stockers. Could it be that those studs were designed to be used with a smaller base circle camshaft?? I have seen several valvetrains lately that seem to have the roller trunion riding on the threads instead of the shank..Either way, longer studs should solve your problem, and a set of girdles will keep it solved...........MP
PS, any chance your pushrods are long???

[River Rat 005]

Yes, longer studs, AND a GIRDLE.......The posi locks are un necesary when using a girdle, so the longer studs don't need to be faced........MP
This is the only engine I have used a studgirdle. Two years ago I got to bagging how maintenece free this engine was. The next day #1 exhaust lock backed off letting the push rod come out. Some how this caused the intake push rod to bend then break. Beat up the intake tip before it broke. When I found this, the stud girdle was still tight on the polly. I thought with the girdle they couldn't come loose. Mine may be a rare deal, but I keep a closer eye on them now. I feel I got off cheap with just a push rod, guide plate and intake valve.
Tim

[Moneypitt]

This is the only engine I have used a studgirdle. Two years ago I got to bagging how maintenece free this engine was. The next day #1 exhaust lock backed off letting the push rod come out. Some how this caused the intake push rod to bend then break. Beat up the intake tip before it broke. When I found this, the stud girdle was still tight on the polly. I thought with the girdle they couldn't come loose. Mine may be a rare deal, but I keep a closer eye on them now. I feel I got off cheap with just a push rod, guide plate and intake valve.
Tim
How did the rocker nut back off if the girdle was tightly holding it? I still use the "posi" lock screw, along with the girdle, but I have seen others that don't for ease of re adjustment between rounds. Regardless, he still needs longer studs or shorter lifter/pushrod/valvestem combinations. I'm not sure how, or why, but I have seen some really screwed up rocker geometry on what appear to be bone stock combinations.......MP

[River Rat 005]

I was wondering how it came lose also. Thats how I found the problem. When I pulled the cover, the nut was higher out of the girdle than the others. I now make sure everything is tight and pull the covers more ofter.

[f_inscreenname]

I understand what you are saying M/P. I have been using Mopar small block for the last 6 years. Shaft mount rockers do not adjust and even a simple cam upgrade will require pushrods (if you can find then) that cost as much as the cam its self.
I did a little research last night and it seems the 1.75 length is the standard size. http://www.cranecams.com/?show=browseParts&lvl=3&prt=114&action=partSpec&partNumber=99157-16
As for changing pushrods........ Not unless its necessary. I really think the roller rocker are the same geometry as the stamp rockers geometry. I think the main issue is the trunion is larger. It also seems pretty funny that it was so easy to find (everywhere) the 1.9 studs. From my caculations they will be a perfect fit. Its almost like they were made for them.http://www.supernova19.com/forumcw/Smileys/classic/clueless.gif

[GofastRacer]

I was wondering how it came lose also. Thats how I found the problem. When I pulled the cover, the nut was higher out of the girdle than the others. I now make sure everything is tight and pull the covers more ofter.
Did you compare the poly-loc to the hole in the girdle?, sounds like there was no clamping force???, if they're right and the girdle was tight, no way are they going to back off!..