I can't really wrap my head around what may have caused wear like this. Nobody's finger pointing or anything, this is a simple attempt to learn from anybody on here who may have a legitimate answer so if it was anybody's error, we can prevent it in the future. Something else that may or may not be related, is most of the combustion chanbers had small cracks (i believe) around the valve seats. There were no signs of detonation on the heads or pistons. My theory in regards to the cam is at the bottom of this post.

Here's the engine mod list along with pertinent history:
02 LQ4 with probably 60k+ miles on this combo
Has been tuned on both E85 and 93 octane at different times
Stock shortblock except for the blower cam
AFR 225 Heads
Magnuson 112 Supercharger pullied for 10psi
All bolt ons.









Since the cam bearings are oiled by crank splash and the damage is on the front cylinders, my only theory is it was run lower than optimal on oil on a regular basis. Only reason I don't think that's the case is because the owner is a pretty mechanically savvy guy. I can't really see him overlooking it that long. Any other thoughts or opinions?

 

what does the lifter look like? What combo was used for the valvetrain?

 

^ what he said...how does the lifter look, maybe it turned and damage the lobe.

 

bad metal or not heat treated right

 

And....
I agree with these guys. And look at the pics below and you will see why. I had a lifter (#4 intake if I remember correctly) eat my Thunder Racing 224 cam. The cam was inthere when I bought it. After I ripped it out and replaced it, I upgraded my lifters to LS7, with LS2 trays. What made you take the cam out? Was the car making a "chirpping" noise? Now is a good time to upgrade the chain.



And here is the lifter that cost me a long weekend and about a grand!!

 

How many miles on the valve springs?

 

Do the AFR heads have the 8019 upgrade springs?

 

I seen a car do that to a eBay regrind cam shaft. Lifter had no abnormal wear. Car made no noise at all. Lifter were actually reused when the new cam was installed. I would have changed them but he choose to run them. We were not even lookin for a problem. Just doing a cam swap and when we got it out that's how it was. Most people that we show it to said it wasent heat treated or hardened correctly. Being a regrind I could believe that. What brand was this cam?

 

Odd that it is only that single lobe.

 

What oil was being used? If you guys with aftermarket cams aren't already running an oil like this: http://www.valvoline.com/products/br...ng-motor-oil/6 then you should do yourself and your valve-train a favor and start using it.

 

Since the cam bearings are oiled by crank splash and the damage is on the front cylinders, my only theory is it was run lower than optimal on oil on a regular basis. Only reason I don't think that's the case is because the owner is a pretty mechanically savvy guy. I can't really see him overlooking it that long. Any other thoughts or opinions? I really hope you don't believe what you posted.The cam bearings are oiled by the oil pump same as the crank and lifters.How are you suggeting oil is splashed on cam bearings when they're surrounded by the block and plugged up with a cam?

 

The car I seen it happen on was also on the very first lobe on the cam closest to the front. Now that I think about it my car ate up one valve stem and rocker once. Guess which one. Drivers side all the way in the front. Ate it almost all the way to the locks for the retainer. Seems to be a pattern.

 

In the OPs pics I see at least two lobes. 3rd photo.

 

Same thing happened to me for only one lobe. I'm thinking a crappy compcams metal hardness. Switching to another grinder.
I had torquer v2 cam + PRC 5.3 heads with all PRC hardware.
If it was the spring pressure, all of the lobes would have the same wear.
All I can think of is either an LS7 lifter took a crap on me or bad compcams core (many cams had similar wear even with the original LS1 lifters).
From the pictures, I can tell lifter wheel metal is harder than the cam..

 

Looks like you were on your way to flattening out the cam. This can happen when someone performs a valve job on the car and tighten down too tight on rockers, which gives you too much spring pressure, causing the valves to not open all the way, which in turns adds extra load on lifters. Hence, the lobe wear. I've had that happen to me personally. Even if this is not was caused your lobe wear on your cam, you better check the oil pan for metal shavings. The worn metal had to go somewhere.

 

George, you're right. Been working on small engines too much recently I guess.

Brian Tooley, I'm not positive about what valve train was being run until I speak with the owner again.

The main reason for the initial teardown was a combination of several things. He'd had what he believed was a weak lifter for a few thousand miles, I believe he had a slight coolant leak from a head gasket near the rear of the motor, and the final straw was a loud knocking/clunking noise that ended up being a busted catalytic converter.

He ended up replacing the motor with a forged replacement with new AFR 230 heads, new valve train and a new cam. So none of the suspect parts were reused, but we would still like to have an idea why it happened.

 

Martin@Tick - He's religious about running Royal Purple synthetic.

 

Then I would say that is an issue in itself. The problem with todays synthetics and normal oils is they do not have enough anti-wear agents present in the oils composition, namely ZDDP which contains zinc and phosphorous(sp.) to name a few. Without these anti-wear agents, things like this begin to happen along with increased rocker arm pad wear and valve tip wear.

Any of you guys that are running aftermarket cams, springs and/or lifters need to be running an oil that carries higher quantities of ZDDP. The cheapest oil that comes to mind that has the minimum amount of ZDDP that I like to see is Shell Rotella Diesel oil. You can get it at Wal-mart in a gallon for like 10-12 maybe 15 bucks at the most. Any other diesel oil will have a minimum of 1100-1200ppm of ZDDP which is good, but there are better oils. Here at our shop, any car that comes through our doors that gets an aftermarket cam has their oil changed and replaced with Valvoline VR1 CONVENTIONAL racing oil. It has over 1400-1500ppm of ZDDP which is more along the lines of what I like to see. It's only 5.50-6.0 bucks a quart so it's cheaper than most other oils available. You can get it at O'reilys, Advanced or Auto-Zone 9/10 and if they don't have it they can order it for you.

Today's oil's that I will refer to as "shelf" oils have to meet EPA requirements for ZDDP which puts it at no more than 800ppm and some of the fancy "greener" oils and "fuel economy" oils have even less! This can spell disaster for a performance engine namely the valve-train that is being put through forces and pressures that these oils just can't protect against. There are also some of the European formulas like "German Castrol" that carry 1000ppm, but we can do better than that with oils like diesel oil and VR1.

Do yourselves, your wallet and your engine a favor and use one of the oils that contain these higher amounts of ZDDP. Now, all that said, I'm not pointing the finger at the oil or that if he had used a different oil this wouldn't of happened, but it damn sure couldn't of hurt anything and it might of been able to avert this from happening.

 

Good info. I will switch oils.

 

Was that the API (new car formula) or their HPS (high performance street) oil.

As mentioned, using the API new car formula oil in an engine with stiffer valve springs & faster cam lobes is going to cause cam,lifter,pushrod & valve
tip wear when using OEM rockers)


Russ Kemp