SBC valve train issue - help

[Bobby Zlatkin]

Got the car out preparing for the 1st race of the season. While setting the timing, I heard a bang, bang, bang & the engine shut off. Sounded like it came from the left side so I pulled the left rocker cover.

#3 cyl., ex. rocker off the valve, push rod bent and cracked to the point of coming apart, stud cut almost in half. Top of valve stem & retainer beat up some.

#3 int. rocker very loose, although still showing the same amout of threads on top as all the others. Made me think maybe it was pulling a stud (press-in). Again stud cut almost in half. This push rod was not bent.

Measured (compared) the length of those two studs and compared with others. Those two are longer, but not by much. If I can avoid it, I perfer not to pull the head. Can I pull and replace the studs with hand tools? If so, what?

Finally, why did this happen? The valves were lashed down properly (hyd. lifters). It's a low lift cam with stock valve strings that never sees more than 6,000 rpm.

[Mike Taylor 3601]

Bobby,
First thing I would do if you have'nt already is while rockers are off, hook air hose straight in spark plug hole to make sure you did'nt bend valve when that happened,should'nt have any air come out in.or ex.,if you do tap on tip valve make sure you don't have some debris
between valve/seat. If it leaks pull it and fix valves,studs then.
You can pull rocker studs by putting washers or a spacer on stud I'd use old rod nut or grade 8 nut lubed well,tighten nut against washers/spacers and should pull stud,may have to add more spacers till you get pulled completely.
You can install new stud w/hammer install nut on threads to protect them leave just enough threads of nut above stud that you are hammering on nut.put some loctite or sealer on stud where it goes in head,drive into head carfefully so you don't bend stud with a missed lick,you can use a straight edge of some kind to measure that stud is even with other studs, BTW drain water some studs go into water.
If tip of valve is damaged where it tries to make rocker push to side, it will cut stud if it does'nt come off first.
Mike Taylor 3601 PS you can get .003 oversize studs if neeed

[Ed Wright]

You guys can't use screw-in studs in Stock?

[Rich Biebel]

You need to look at the lifters and cam.......
Press in studs in a small block used for racing is not a very good idea. Wasn't a good idea with hot street cars in the '60's

We pinned the studs in the '60's
We used cast pins as the common roll pins broke the heads before the pins broke

Not sure what started or caused your issue but it can easily cost you an engine

What engine/cam/lifters/ solid or hyd. /spring pressure?

[ron mattson]

Like rich said you need to look at the cam and lifters also, it almost sounds like
you have a clearance issue somewhere. piston to valve could be tight, also make sure
the rocker arms are not running out of travel on the slot.

[Bobby Zlatkin]

Mike, some good suggestions. Also, on the damaged valve tip, I think I'll use a LT1 self centering rocker arm hopefully to keep that out of further trouble.

Ed, I'm running IHRA Pure Stock and aren't allowed screw-in studs. Crummy rule, but that's why they call it pure stock.

Rich & Ron, I will look at the cam & lifters but, hopefully the hyd. lifters cushioned any possible damage there. With a .390/.410 lift cam at stock duration, interference shouldn't be an issue. I hope.

I know I should pull the head, and I may have to, but I'm trying to get away without doing that.

Thanks for the responses.