I have 3/8" rocker studs (CompCams) with Crane Gold 1.6 roller rockers and this is the 2nd time I've broken a rocker stud. Is switching to a 7/16" stud going to provide the extra strength I need?
BTW this was an intake rocker stud that broke and the intake lift is .540" (exhaust is .555")

------------------
1987 383 cu.in. IROC-Z: TPIS MiniRamIII / GM FastBurn heads/ 10.6:1 compression
Comp cams custom grind: Dur'n 224/236 Lift .536/.555
Strange 12Bolt Diff./ Neil's Home-Built BulletProof 700R4+Vigilante 2800 stall converter
MSD Billet Distributor, Dig 6+, & Blaster coil
Hooker Supercomp Long tube headers

 

I'm not sure what your problem is, but with a cam that mild, you SHOULDN'T be breaking 3/8 studs anyway, so I'm not sure that 7/16 will help. What kind of cam is it a hyd flat or roller, or is it a solid flat or roller?? I have ran solid flat tappets with more lift and dur than your's with pinned factory 3/8 studs in Super Street dirt engines and had no problems with breakage, which is why I think you may have another problem, since you said you were breaking "good" 3/8 studs. It sounds like a geometry problem, you may want to get a pushrod length checker. They only cost around $10.00 and it would tell you whether you needed a longer/shorter pushrod. I have a Comp custom ground Hyd Roller in my 82 Z28 (see sig)and they ground it on a .100" smaller basecircle because it was would give more cam to rod clearance in a 383. If you have it custom ground, then I'm sure they asked what cu. in. it was, and they MAY have ground it .100" smaller w/o telling you. I would definetly check the geometry since you're gonna be under the valvecovers anyway.

------------------
82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.60 @ 114.56, w/ a 7.34 1/8 @ 93.50, and a 1.622 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock

Bassett Racing

 

I'm not sure what your problem is, but with a cam that mild, you SHOULDN'T be breaking 3/8 studs anyway, so I'm not sure that 7/16 will help. What kind of cam is it a hyd flat or roller, or is it a solid flat or roller?? I have ran solid flat tappets with more lift and dur than your's with pinned factory 3/8 studs in Super Street dirt engines and had no problems with breakage, which is why I think you may have another problem, since you said you were breaking "good" 3/8 studs. It sounds like a geometry problem, you may want to get a pushrod length checker. They only cost around $10.00 and it would tell you whether you needed a longer/shorter pushrod. I have a Comp custom ground Hyd Roller in my 82 Z28 (see sig)and they ground it on a .100" smaller basecircle because it was would give more cam to rod clearance in a 383. If you have it custom ground, then I'm sure they asked what cu. in. it was, and they MAY have ground it .100" smaller w/o telling you. I would definetly check the geometry since you're gonna be under the valvecovers anyway.

P.S. My Comp custom grind is .580" int, .599 exh, with 240* int, 248* exh @ .050" and I am running 3/8 studs.

------------------
82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.60 @ 114.56, w/ a 7.34 1/8 @ 93.50, and a 1.622 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock

Bassett Racing

 

Check to make sure the valve guide is cut down far enough to allow that much lift. Also if you're breaking studs, check to see if any pushrods are bent.

------------------
Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

Definately a bent pushrod is a sure fire way to tell if they are too long and your geometry is off. Have your shaved your heads any? Re-decked the block? Thinner head gasket? A lot of "little variences" will equal up to "way off"...

------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Your problem isn't the studs, even though that's where the symptom appears. Sounds to me like you have the GMHPP valve spring problem... you're not the first. Those springs, like any other 1.25" springs, are only good to .500" lift, and very little more.

Get those off of there, and put some real valve springs on. I'd recommend Comp 987, but ask them for their suggestion. That should take care of the problem. You will probably have to have the heads machined out to accept 1.45" springs, instead of the stock 1.25" ones that they supply.

Hopefully you haven't already wiped out the cam.

BTW is the cam you have the custom grind with the 276 intake lobe, or the XR282HR whose specs are in the text? I have the 282 in my 400, with 987 springs, 3/8" studs, & Comp 1102 roller rockers, very similar setup to what yours should be, it rocks. No parts breakage.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

I won't say that your studs breaking are a definate sign of a problem, but they probably are. Before assuming that it is a stud problem you must carefully check over the entire valve train. As previously suggested, some stock performance springs bind and have problems above .500" lift still. Check for pushrod contact with the head, check for retainer->guide clearance, check coil bind, check geometry, check for faulty rockers, etc. You may also want to check for valve guides and valves for signs of trouble. Reoxygenated gas is hard on guides, maybe your guides are a little tight or losing lubrication when they are hot. The extra force is driving your studs over the edge. If everything still looks perfect then try the 7/16" studs. But if something else is wrong next time it won't be a broken stud. Still, I'll put my money on a geometry problem. Roller rockers are harder on the studs since they don't really give any when twisting sideways. This is not the stud's fault but rather the valve train settings.