5th run at the 1/8 mile track I start hearing a nasty clacking sound so I coast to the end. Initially I thought it was detonating like crazy because I had advanced the timing a bit before the run, then I thought (later proved correct) that somehow a rocker arm got loose and was hitting the valve cover on the drivers side. Stubborn me, without tools at the dragstrip, just drove it home. The clacking stopped but it was running rough as hell and stalling at stops.

So when I get home I open up the drivers side valve cover. What a mess - almost ALL the rocker arms are loose, pushrods just hanging loose, lifters thrown about inside. I assume the passenger side is OK, how the heck did I even make it home?

First question - How did this happen? Maybe the one loose pushrod or lifter was knocking around and cause some kind of domino effect on the other pushrods on the left side while I drove home?

Second question - What kind of permanent damage am I looking at? I don't see any initial signs of damage - no bent pushrods that I can see, valve springs still intact (but who can tell). I don't think it was caused by valve float because I was still in first gear. Tommorrow I will take off the manifold and put the lifters, pushrods, and rockers back together and tighten everything down. Do a compression test, etc. What are my chances that everything will be OK after that?

I can't beleive this. As always I have myself to blame. A few months ago I loosened the rocker arms a bit and must have not tightened it down enough. Well, all is not lost, I did get a best 1/8 mile run on the second run.

 

Man, those kind of noises always require you to STOP, but d*@m I know how you feel, you don't EVEN want to look.

If in fact they just "backed" off, there may be little damage, but one good reason for them to be loose is that you wiped your cam. Check the lifter faces when you have them out, it could be ugly, lets hope not.

Good Luck!

 

I don't think I wiped the cam, the lock down thread on the number one (can't remember if it was exhaust or intake) rocker was completely backed out...it just got loose. I'm just worried about the drive home with 8 valves not functioning.

 

Hi, Did you have oil pressure ?? Peace,,,,,,,,,,,,Craig

 

I kept a good eye on oil pressure the entire time - stayed atleast at 40. No problem there.

 

drove it like that...

 

I'll assume you have some sort of aftermarket cam and springs in this engine. Stock rocker nuts will do this and all you need to do is replace them with the locking style if that is the problem. If you don't have screw-in rocker studs, you will also need to check and make sure that the studs aren't pulling out of the head. For any racing, I highly recommend fitting screw-in studs,lock nuts and guide plates to prevent these kinds of problems.

Hans

 

Valve float occurs from high rpm's regardless of what gear you are in, what was your shift rpm?

 

I guess this was the low-buck version of "displacement on demand"... like the new hemi that turns off 4 cylinders on the highway.

If you still have stock rocker nuts, it is time to replace them. They're deformed slightly so they stay put but after so many times taking them on and off they loosen up to where they turn too easily. Any autoparts store will have new nuts. Unless the lifters popped out of their bores there's no reason to take the intake manifold off.

 

Cam is a comp cams 280 with matching lifters.

I shift at 6,000 RPM but I don't think it was valve float, I have aluminum roller rockers and stainless steel valves that should have easily taken that RPM, I have no idea about the spring rating however. Also I could see the one roller rocker stud simply backed off.

I have to take off the manifold, I can clearly see the lifters poped out of the bores when I look inside the valley with a flashlight.

OK this brings up another question. Assuming I lived a good life and it all comes back together without damage - I do not have guide plates per se on the aluminum L-98 heads I have. The crane "gold race" roller rocker arms are described as "self alligning". I do notice however they get cocked at an angle rather than 90 degrees to the valve even before this problem. So what's the "self alligning" (sp?) mean?

 

Self aligning rockers have small guideplates on each side of the rocker that keep it on the valve stem. Make sure you get ones for your specific head either reg or center bolt, center bolt require a narrow body rocker. Summit has their own brand name ones, not sure who really makes em though.

 

When I had my engine done many years ago by folks who drag raced regularly, they epoxied "trash screens" over the oil drain back holes in the heads and lifter valley. This is cheap insurance for keeping the bottom end intact when troubles occur up top. This is somehting you may want to consider doing when the engine is open.

 

"Self aligning" rockers are better than stock, but are still marginal for pushrod deflection at the terminal RPM your running. Since guide plates require machining your heads for screw-in studs, go with what you have for now. 6000 RPM is probably also marginal for stock seat pressure and springs, so hopefully you have something slightly better. I would pull the covers fairly often (say after every ten passes or so) anyway 'till your sure everything is stable, plus you can get in there and check for any cracked or broken springs and related parts.

Hans

 

True, but I've also seen the epoxy let go dumping epoxy shreds and metal screen into the oilpump.

 

zwede: I installed the screens in my motor, and i'm glad I did. After 1 year of abuse they look just like they did when they went in. They also did their job when I had a pushrod blow out the side of a lifter sending the pieces to the back of the motor, the screen was there, I just picked them out, replaced the broken parts and have been haulin all summer, it would/could of been worse.

 

For this screen are you talking about a valley baffle? I see in my Jegs catalog they sell one for $22 or so. I'll order one tommorrow if you guys think that is good insurance.

Ok took the manifold off. Three lifters were knocked out of the bores. All pushrods except one were either laying on there side in the lifter valley or were loose and no longer set in the rocker arm. The passenger side was fine. Looked at a few lifters, they look fine, no visible wear. Looked at the pushrods, none bent. Looked at the springs and from what I can tell they look intact and undamaged. Rocker arms look OK. Already screwed everything back in place. So cross my fingers, tommorrow or the next day I will button up the manifold, and start it up and reset the lash.

 

Not at all the same, but a lifter valley baffle is a nice feature and I fabricated and installed my own under my Performer RPM. (The secret to power in in the details.)

A lifter valley baffle is there to keep the hot oil in the lifter valley from splashing up on the bottom of the intake manifold and heating up the intake charge making the mixure less dense. Believe it or not, the GM manifolds have a similar-type application where they have a stand-off shield around the bottom of the manifold, but the purposes is just the opposite. In the GM application, it's to keep the hot exhaust gas in the crossover under the carb from cooking the oil into "coke."

Moroso makes a trash screen set and it is listed on Page 124 of the March/April Summit Racing Catalog. Moroso Part # MOR-25000 for SBCs. I think my mechanic just used a strong, fine metalic screen material cut to shape.