Built LT1

iTrader: (3)

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 also 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 the rocker 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.

Gregory

iTrader: (4)

Perhaps the rocker arm studs are pulling out or unscrewing.

3.4camaro

iTrader: (1)

Did he use loctite?

rob97ss

iTrader: (1)

Who set up the heads?Are the springs set up right?Pushrod length?What rockers are you using,SA or NSA.with or without guide plates?just some things i would look into.

Boodyrider

iTrader: (2)

Sounds to me like you need to have the 'reputable' shop that built the motor take a look under warranty.

Built LT1

iTrader: (3)

The shop has agreed to look at it, I don't know what they plan on doing yet.

Built LT1

iTrader: (3)

The engine builder himself built and set up everything. I don't know the push rod length or the brand of rockers. However, the rockers and pushrods have been replaced with new ones, the difference now is that the second set of rockers are made of steel instead of aluminum.

I don't know whether they're self-aligning or not. I think they do have guide plates. I have recently found out that the stock springs (the ones that come with AFR 210 heads) were left on instead of the K-Motion; apparently they had ample spring pressure for the custom solid cam?

Built LT1

iTrader: (3)

Update:

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

WE TODD DID

iTrader: (2)

Seems like the valvetrain geometry is out of wack. Pushrods might be too short or something to that effect. Need to make sure you have guide plates with stud mount rockers, or it will **** the rockers up like what you're talking about. Might want to consider taking it to someone that knows what they are doing!

scites

iTrader: (30)

might have something to do with the valve springs. If the valves are floatting, the pistons hit the valves and boom **** gets broken..IE push rods, rocker arms, valves..just a shot in the dark

onephatZ28

iTrader: (8)

Is this your engine builders 1st LT1 engine?

Built LT1

iTrader: (3)

That's what the engine builder thinks is the proximate cause. I was told originally that it had K-Motion valve springs, but I just found out a few days age that he took them off and put on the ones the came with AFR 210 "race ready" heads. He said those springs are sufficient for solid set-up's and also checked the spring pressure.

It's not that those springs aren't good for most of the off the shelf grind cams out there, but I was totally surprised that springs on a set of race readies would handle a solid roller cam that has almost .650 lift and over 250 (exhaust side) degrees of duration at .050.???

Built LT1

iTrader: (3)

Yes.

I'm not sure if makes a difference from a mechanical aspect, but as far as things unique to the LT1/4 engine, he made a few mistakes. For example, installing the opti-spark incorrectly, and ordering factory LT1 intake gaskets (read way too small) instead of the GM performance parts LT4 "race" intake gaskets, which were much larger and fit fine.

Built LT1

iTrader: (3)

The engine builder has the car now. He's a stand up guy and is going to make it right. Hopefully, he'll ascertain the cause and get the engine back to where it should be.

onephatZ28

iTrader: (8)

What the hell happend to your High dollar K-Motion valve springs?
It sounds like your builder is trying to pull a fast one. You should get your **** and
run. If I paid for something to be on my motor, and I get it back and the stock **** is still on it, I would be ******* mad. You should find a new shop!

Phill

Don't get fucked for a 3rd time

Built LT1

iTrader: (3)

Fortunately, he's not trying to pull anything. He told me that he took that additional charge off, and it was in fact reflected on my invoice; I just never looked at the details of the build sheet that carefully, just the cam card.

He's been honest with everything so far.

onephatZ28

iTrader: (8)

It just suck because you did not have this much trouble with the engine that Chuck built
you, and you got that engine hot alot of times.You just had alot of trouble with the trans.

Awake455

Before ya get that far, is it his first pushrod engine?

Black FormulaLs1

iTrader: (10)

this is exactly why i own an ls1 best of luck to you

onephatZ28

iTrader: (8)

I have a LT1 too