Hey guys, I want to know if gm used the same exact stamped steel rockers when they switched to roller cams in 87 as they did with the flat tappet cams, I'm trying to chase down a valve tick and I'm pretty sure geometry is the issue on my 113 heads, I used self aligning rocker arms from a set of 217 iron heads which was paired with a flat tappet cam, when everything is tightened down the rocker studs seems to be showing a lot of threads which I don't think is normal

 

No. Well, not always.

The difference is in how they are guided. Older motors used holes in the heads that the push rods fit somewhat tightly in, to maintain their alignment. Some aftermarket setups use guide plates like you have there, which do basically the same thing, and REQUIRE that the holes in the heads be opened up to allow the push rods to go wherever the guide plates want them to go. Both of those systems REQUIRE that the rockers be COMPLETELY FREE to be guided by the push rod. They CANNOT be used with "self aligning" rockers. SA rockers also REQUIRE that the head holes be completely clear of the push rods, and ARE INCOMPATIBLE WITH guide plates also, because the rockers will attempt to locate THEMSELVES regardless of where the push rod tries to locate them. Thus, SA rockers will "fight" with either of the other systems to be "the one" that locates the rocker; and we all know what happens when one piece of metal is forced to try to be in 2 places at once.

One, and ONLY ONE, of these systems, MUST BE in effect at all times. ONE AND ONLY ONE. Since you have TWO in place – both self-aligning rockers AND guide plates – then you're lucky nothing has bound up or bent push rods or otherwise failed catastrophically. Like, REALLY LUCKY.

Get those self-aligners off of there NOW before something REAL BAD happens.

Meanwhile, you're not supposed to "tighten down" the rockers. You're supposed to "adjust" them: you tighten each of them until all the vertical FREE play in its lifter and push rod is taken up, then tighten some small amount more, to add some preload to the lifter plunger. The amount of preload you might use is something you choose based on how the motor is to be used, and can vary, from almost none in some pure racing setups that will get frequent maintenance, to ½ turn or so which is about what most people like us would typically use, to as much as a full turn for a factory style build where you'll put it together and expect it to remain untouched for hundreds of thousands of miles. How much preload did you set yours to?

Then, your situation is complicated by the guide plates and screw-in studs. The top of the stud bosses MUST BE cut down at least enough to make them flat, which appears to have been done to your heads; butt then the thickness of the plate, in combination with however much material was removed from the bosses and the length of the studs, will determine how much thread is left exposed when the nut is at the proper height. Without knowing exactly what the machinist did to your heads and exactly what aftermarket parts you have, it's impossible to predict that. And of course, aftermarket studs like you have, come in all sorts of variations; no telling how yours might compare to any factory setup.

So you need to do 2 things IMMEDIATELY if not sooner: GET RID OF those SA rockers RIGHT NOW, and put on some that are free to allow the push rod to locate them wherever the guide plates constrain the push rods to; and properly adjust the valves once that is done. I also STRONGLY recommend getting rid of all that STUUUUUUUPID factory crap dead-weight CRAP on top of the springs – those USELESS oil splash shields and those HARMFUL "rotators" on the exhaust valves – and put on some new good-quality valve springs, properly set up to the correct installed height, which would most likely be 1.75" for any typical 1.25" OD springs that would directly replace what's there without requiring further machine work (spring pocket cutting) to the heads. If you don't have "positive" seals on the valve stems, I'd recommend changing to that type at the same time, since you'll have it all completely apart anyway. Might as well make it right if it's not already.

 

I should have noted also:

The stud bosses MUST BE cut for aftermarket guide plates and screw-in studs like yours to be installed. HOWEVER, they cannot be cut TOO much, or else the bottom of the studs will protrude into the casting through the water jacket so far that the bottom end of the intake rocker studs will bottom out on the outside of the intake ports. The head castings are hollow of course, with coolant flowing around inside; and are cast in several steps, such that the exterior of them is cast after the various farther-inward parts, such as the ports, are cast. The ports each look sorta like little tubes in there, of a strange shape of course, butt a tube nonetheless. Each portion of the finished casting is rather thin; maybe 3/16" to as thin as 1/8" in some places. Those stud bosses "look like" big beefy chunks of metal, solidly and securely cast in place, butt in reality they're just a big blob on top of the almost tissue-thin outer "skin" of the head. So, depending on the specific studs that those happen to be, if the bosses were cut too aggressively, the studs wouldn't fit, or would possibly even break the intake port if somebody tried to gorilla them in past where they make contact. Likewise, if the guide plates were simply left out (which would allow the SA rockers to work successfully), the deeper protrusion of the studs might get into the same situation.

So, later this afternoon while you're taking care of the dangerous incompatibility you are rectifying, pop the intake rocker studs out, and LOOK AT the intake ports below them; and verify that the studs haven't been hitting them. It's also not impossible that if the studs bottomed out, the installer may not have tightened them up past, say, some torque wrench setting, in which case, the intake side of the guide plates might be loose. Guess how much of a tapping noise THAT might make...

Your "tapping" then, could be caused by ANY NUMBER of factors, or even more than one, from among these causes, and/or others:
-

• Rockers improperly adjusted
• Rockers IMPOSSIBLE to adjust properly because the studs are up so high that their threads are up so high that the nut bottoms out on the end of the threads before the vertical play in the lifter plunger and push rod is taken up
• Push rods binding on the guide plates and either hitting up against them at whatever point(s) in their travel, or "sqweeeeeking" as they are forced to rub against the plates, which sounds an awful lot like a "tap"
• Rocker self-aligning ribs riding up onto and back off of the valve stems
• Push rods already bent from side loading, and slapping against the guide plates
• Guide plates loose on top of the heads
• Damaged cam lobes, which may or may not have anything directly to do with the head setup, butt may be just the inevitable flat-tappet death that can't be helped these days, or may be due to damaged or misaligned lifter bores
• And of course all the usual "tapping" things like springs rubbing on their dampers, lifters whose piddle valves don't seal aka "collapsed" although I'm not sure why people call it that, wear on the rocker tips, and so on

In general, you have some sleuthing and investigation to do, while cleaning up all this mess, to make sure you haven't left anything undone that needs to be done.

 

And don't forget, the studs go into the water jacket, meaning the threads MUST have thread sealer applied. Use the Permatex/Loctite "high-temp automotive thread sealer with PTFE", and especially NOT any type of RTV.

 

Pretty sure that those are 'Vette/113 heads and as such, those "guide plates" aren't real guide plates; they're assembly plates used for...something (holding the pushrods while putting rocker on?) What ever their purpose, the slots in them are "too big" for actually guiding push rods/rockers and therefor, they shouldn't interfere with the SA rockers. In fact, all later 'Vette L98 113 heads came with both SA rockers AND those "guide plates", from the factory.

 

yeah they're not real guide plates they were only used for assembly purposes to center the pushrods due to the casting not having any alignment holes from the factory

when I got the heads someone had those needle bearing death machine cheap amazon roller rockers on there, its entirely possible maybe they switched the studs out to accomidate those? I also set my lifter preload to half a turn with the engine hot and running very slowly, maybe that threw off the adjustment because I was giving the hydraulic plunger enough time to take up slack and not give me a proper reading. The tick isn't that loud by any means, it's just there intermittently and only started after I did my valve seals. Originally when I swapped these heads on I adjusted them 1/2 a turn down with the engine off and there was ZERO valvetrain noise at all.

 

Those studs look stock, to me.



I think that I would go back and adjust them the way that you did it, originally.

 

Did the adjustment (twice after losing count) and it worked for a minute, drove around the block and when I parked it sounded like valvetrain death, when I took the valve cover off one of the adjustment nuts were almost completely unthreaded, glad I found it, looks like I just need new nuts and that they weren't holding adjustment

 

That would do it.

So many parts get reused when they shouldn't be. I hate seeing someone rebuild a 1970's SBC and reusing head and rod bolts. Throw them out and buy new parts. Rocker nuts also wear out and pressed in studs with high spring pressures can pull the studs out of the head. Yours are screw in so thats not a problem.

The protruding stud on yours may be simply because you have guide plates which raises the stud position. Do the rocker nuts bottom out on the base of the studs?

 

The rocker nuts have a pretty decent amount of adjustment before they bottom out on the stud. The only thing I'm confused about is why exactly the stud is protruding. I'm using the summit 8800 cam which to my knowledge should have the same base circle as stock, stock roller lifters and stock pushrods all from a 1988 LB9 305. The only thing I can imagine is if the corvette heads got different length pushrods but I haven't seen any evidence to back that up.