I need some ideas on why my valvetrain is repeatedly breaking. I am not racing the engine, nor have I even dynoed it yet; in fact, I haven't even switched to synthetic.

The motor is a solid roller stroker LT4 engine that was built by a reputable shop. No expense has been spared with this engine, it has the best of everything.

After a few hundred miles, the valve train was making quite a bit of noise. I removed the valve covers and discovered that two rocker arms were destroyed with metal pieces EVERYWHERE. I drained the oil and meticulously removed all visible metal fragments. The engine builder said he "discovered" what happened (something to do with the rocker arms themselves?) and would replace the rockers with newer, stronger rockers and obviously re-adjust the valve train. He even installed new push rods.

I picked the vehicle up and it drove fine for a little over 100 miles. Yesterday, I'm on the freeway cruising at only 60 mph, and the valvetrain begins to get slightly louder, like it did when I first had this issue. I thought to myself not again, I'll have to remove the valve covers and see if anything visibly wrong. Within a couple of minutes, my engine all of the sudden sounded like a jack hammer was being operated under the hood. It was back firing and missing and the car lost power and died.

After I got the car home with a tow truck, I removed the valve covers and discovered that cylinder #8 was missing a lash cap. The rocker was alos so loose, that I could put the lash cap back on and fit a pencil in between the cap and the roller tip. Cylinder #3 was really bad, the rocker arm was sideways and the pushrod was bent approximately at a 70 degree angle coming out the head. On cylinder #5, the rocker arm was just laying in there as if it was detached (you can spin it around) and the push rod isn't even touching it; the lash cap was missing on this spring as well.

I'm wondering what the problem is. This street strip motor was built with the express instruction that daily driveability is required.

Any thoughts? I'll answer the questions as best as I can regarding component information.

 

what kind of rockers failed the first time?

Whats the piston to valve clearance?

 

I don't know what brand was on there the first time. I do know that they were 1.6 ratio 7/16ths aluminum rockers.

I have no idea what the piston-to-valve clearance is.

 

Sounds like the poly locks are backing off from not being locked down tight enough IMO.

You DO have poly locks don't you?

 

Yes

 

Make sure they are tight. Some studs won't let them lock right.

 

yeah...I have seen that before. the top of the stud will not let it lock right

 

Humor me, what do you mean, Best of everything,no expense spared? What parts are you running?

 

Remember they are aluminum stud mount rockers.... best of everything

Not to bust on you man, but that's far from it.

Anyways sounds like someone needs to tighten that polylock DOWN!

 

I think this is a good question. You should have an itemized list of every part that went into your motor. What parts make up your valvetrain?

I've seen so many times where people THINK they have this top dollar, bulletproof setup, then you look at the parts list and find out they have crap. I hope that's not the situation here.

 

I don't mean to be rude, but it doesn't sound like he has a set of Jesels on there.

 

I don't know all the valve train components.

Obviously, it may not be the best of everything, but I expected that whatever parts to be used would be adequate for a reliable street strip motor, especially after putting upwards of $15,000 plus into this engine.

Some of the parts include special order JE nitrous pistons, Manley H-beam rods, a forged stroker crank that's knife edged, a 4 bolt main block, AFR heads with titanium components, supposed "special" lifters and valve train components from Comp to work specifically with their custom solid roller cam.

I don't know why he put aluminum rockers on the engine to begin with. I'm actually hoping that someone on here could explain why someone would do that!

I don't know enough about solid roller set-up's and requirements to comment or advise intelligently on an optimal solid roller set up, which is why I trusted these decisions with a professional; and posted my questions on a section of this site that deals with advanced questions such as the one here posed.

Perhaps he cut corners and profited at my expense, maybe he's inept at what he does, and I mistakenly over estimated his abilities. Maybe there's a reasonable explaination as to why I'm experiencing repeated valve train failures.

All input is appreciated.

 

The first time it came apart ALL the rockers came loose. This second incident you can read the damage in the opening of this thread, and yes, several rocker are loose again.

He's asked me if I've been driving the engine hard and I haven't. It just seems that he's infering that I'm somehow the cause of the valve train falling apart.

 

Update:

The engine builder says the heads must come off. He thinks at a minimum that the valves are bent.

 

How else would you drive a solid roller LT1??

I think you have an engine assembler problem.