Rocker Stud Snapped!! What Roller Rockers In Photo

[90 lx convert]

90 silverstang, normally I check an intake and exhaust on each side. If I know all the parts are right and the machine work is done right that is good enough. If it's a mystery motor and I don't know for sure what work has been done to the block and heads then you might want to check another cylinder or two. Depending on the cam you may have all one size rods or one size for exhaust and one for the intakes. If it's a dual pattern cam then you'll probably have a size for intake and one for exhaust. You don't need to size each valve. If two intakes or exhausts are that far off from each other something is really wrong. Keep in mind that this checking should be done when building a motor or changing heads, cam or rockers. If you're doing the work yourself then learn how. If your mechanic is doing the work ask him if he does it. If he says it doesn't matter find another mechanic. Mike

 

[90silverstang]

90 silverstang, normally I check an intake and exhaust on each side. If I know all the parts are right and the machine work is done right that is good enough. If it's a mystery motor and I don't know for sure what work has been done to the block and heads then you might want to check another cylinder or two. Depending on the cam you may have all one size rods or one size for exhaust and one for the intakes. If it's a dual pattern cam then you'll probably have a size for intake and one for exhaust. You don't need to size each valve. If two intakes or exhausts are that far off from each other something is really wrong. Keep in mind that this checking should be done when building a motor or changing heads, cam or rockers. If you're doing the work yourself then learn how. If your mechanic is doing the work ask him if he does it. If he says it doesn't matter find another mechanic. Mike

90 lx convert,
Do I need to use a solid roller lifter with a adjustable pushrod and light springs to check the pattern on the valve stem? I'm trying to avoid removing the lower intake. I was told I could use the light valve spring with the adjustable pushrod without using a solid roller lifter.

 

[junkyardwarrior]

Something was sticking. Valve probably. Maybe tight in the guide? I can't think of any other reason the pushrod would bend other than binding AFTER the stud broke off.

Not uncommon to see 3/8" studs being too short from factory. You only have a few threads up inside the nut. Then tighten (or over tighten) the lock which stresses the threads even more. Heat + running pressures = snap. Longer stud fixes that problem. Or 7/16". Or longer studs and girdles. Or shaft rockers (best).

If it were me, and obviously it's not, I'd pull the spring off and check to see if the valve is moving freely. If it's even the least bit tight, chances are it bound while running, which also would explain the bent pushrod and even possibly the broken stud. Definitely want to find the root cause-because chances are that if one failed, the other 15 aren't far behind.

good luck.

 

[90silverstang]

Something was sticking. Valve probably. Maybe tight in the guide? I can't think of any other reason the pushrod would bend other than binding AFTER the stud broke off.

Not uncommon to see 3/8" studs being too short from factory. You only have a few threads up inside the nut. Then tighten (or over tighten) the lock which stresses the threads even more. Heat + running pressures = snap. Longer stud fixes that problem. Or 7/16". Or longer studs and girdles. Or shaft rockers (best).

If it were me, and obviously it's not, I'd pull the spring off and check to see if the valve is moving freely. If it's even the least bit tight, chances are it bound while running, which also would explain the bent pushrod and even possibly the broken stud. Definitely want to find the root cause-because chances are that if one failed, the other 15 aren't far behind.

good luck.

Junkyard,
The exhaust Rocker stud snapped, the intake pushrod bent on the same cylinder.

 

[90 lx convert]

If you want to check the pattern you can do that without changing anything. Do as Rick suggested and look at the wear pattern that exists on the valve stem now. You could do as I suggested and place a dab of white grease on the stem and turn the motor over several times by hand and see what the pattern is. The only time you need the solid lifter, weak spring and push rod checker is when the pattern is wrong and you need to change the rod length to correct it. That is why the checker is adjustable, to allow you to lengthen or shorten it untill you obtain the correct pattern. Once you get the adjuster set to the right length measure it with a slide caliper and you'll know what length you'll need. Mike

 

[90silverstang]

Thanks for the help. Defintely learned a lot these past few weeks. I did check the patterns on the valve stems as Rick explained, and looks like the patterns are narrow and centered. I also put the light checker springs on cylinder #5 where the exhaust rocker stud snapped. The intake and exhaust valve move freely up and down with no bind. Moved the valve stem side to side on both intake and exh valve to check side play. Checked out good. I installed a new set of longer ARP studs on the heads.I checked the geometry with the light valve springs on cylinder #5 as well. All looks good. Ordered a new set of TrickFlow 6.400" Chromemoly pushrods.
I will post a report when I install the new pushrods adjusting valve lash and start the engine.
Thanks again

 

[90 lx convert]

Good job. Breaking stuff is no fun. The only good part about it is learning why it broke and how to fix it. Mike.

 

[grainboy]

Just my two cents, but my engine did the same thing when I had valve to piston contact. I drove it short trips for a month, with no problems, then went on a road trip and broke three rocker studs, bent a pushrod, and dropped a valve.