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The original was posted on /r/cars by /u/VividKibitzer on 2025-02-05 18:38:25+00:00.

TL;DR: Ended up making a poor financial decision in financing my dream car, ended going through the rabit hole of blowing up an the LS7 motor, and purchasing a built LS7 that ruined its reliability. Got rid of it and reflected on the past mistakes I have made up to this point, hoping it can help anyone else who wishes to buy a similar car in the same position as me.

The C6 Z06 has been my absolute dream car since I was 5 years old (now 23), I remember the fondest memories of driving the car in video games such as Need for Speed Carbon and Pro Street. I also used to obsess over car magazines reading the individual facts like 0 to 60, 0 to 100, quarter mile times, and lap times in the likes of Car & Driver, Automobile, Motor Trend, and Road & Track. I just loved how the Z06 car was essentially the US’s answer to Europe, stuffing a big ol’ Pushrod V8 into a 3100 lb chassis consisting of aluminum fiberglass, and balsa wood.

Last year I happened to come across a great deal on a C6 Z06 that was completely bone stock and unmolested. From my perspective I thought this was a sign that the stars were aligning; I’ve been an engineer for a year and my monthly income was more than ever, and I racked enough savings for a decent down-payment on the car at an interest rate I was “OK” with (6%), given it was a used car that was 14 years old. If y’all ever watched Interstellar, remember that scene where Cooper was screaming his heart out, telling Murph to stay? Well, that is the present day me screaming at the me a year ago who was about to take the keys of his new to him Corvette…

If any of y’all have every owned a C6 Z06, you will have come to know the quirkiness that is the LS7. Essentially, the motor is a SBC consisting of titanium connecting rods bored to hell, with cylinder heads possessing enlarged valves and aggressive valve angles, all culminating to a lightweight, N/A powerplant that produces 505HP in stock form. With an aftermarket cam even with the stock bottom end internals, its common to see these reach 650WHP (700+ HP to the crank) with sufficient breathing mods. However, I think there are two people who exist in this world: those who are attracted to the Z06 because of the LS7, and those who are detracted because of the LS7.

The LS7 suffers from a fatal flaw: its cylinder heads. Due to the enlarged valve and aggressive valve angles akin to a race motor, along with manufacturing defects that make the valve and valve guides “nonconcentric”, it is not uncommon to experience something known as a “valve drop”. This is where the surfaces of the valve experience so much wear due to side loading stress, that the valve stem breaks inside the combustion chamber, essentially causing total motor destruction. Remember how I mentioned the LS7 is a “SBC bored to hell?”. Well because of this fact, the cylinder walls are extremely thin and prone to cracking in the event of a valve drop, rendering the motor useless for rebuilding.

Unfortunately for me, 1000 miles after purchasing, this valve drop ended up occurring. Mind you, this motor was completely stock; stock valvetrain, stock cam, etc. I would have gotten cylinder heads fixed first thing, but local corvette mechanics who apparently had 10+ years of experience of working with Z06’s persuaded me the valve drop was a simple “internet myth”, meant to troll and scare people online. Let’s just say I don’t associate myself with that shop anymore after that statement…

Now here’s the dilemma when a valve drop occurs: the motor essentially becomes useless due to the block cracking, and Chevy no longer manufactures the LS7. This means you will have to either build the LS7 from the ground up with off the shelf parts or buy used. For me, I ended up buying used and happened to come across an LS7 with “fixed” heads and a Stage 3 Cam. At the time I was travelling in out of the state for my job, so I was unable to install the motor myself. So, out the gate, I had to fork over $20,000 to buy and install the new motor.

The reason why I put “fixed” in quotes is that while several companies claim to have solved the LS7 issue of dropping valves with new valve guides and coatings, this doesn’t address the geometrical issue with the heads themselves that I mentioned earlier: valve angle, concentricity error, and oversized valves. All three of these factors lead to valve guide wear, regardless of what changes you make to the materials themselves. This is because the stresses experienced by the valvetrain remain the same unless the geometry changes. Also, when you upgrade and change to a camshaft with aggressive lifts and durations, this enables more stress on the valvetrain, as greater spring pressures are required to close the valves in time to prevent valve float at higher RPM.

Whelp, 10k miles after driving on this donor motor with “fixed” heads, the car gradually began blowing blue smoke… and the reason was because of the above! Even with “fixed” heads, the valve guide wear was still occurring (and at an accelerated rate due to the larger stage 3 cam), causing oil to blow-by the valve seals in the event of RPM deceleration. This is because when you let off the throttle after reaching some RPM, the motor experiences a vacuum condition in the crankcase. This vacuum allows for oil to suck through the valve stem seals if sufficient wear has occurred to either the stem seals themselves, or the valve guides. In my case unfortunately, it was the valve guides. This means that my “fixed” heads, which had approximately 15K miles on them, needed to be “fixed” again. For reference, I drove the car nearly 15k miles after owning it for a year, so this means I would have to open my motor every year…

So after $5000 of getting my cylinder heads removed and “fixed” again, this is where I had to reflectively think of my future with this car: over the course of the year, I spent nearly $30k on a car worth a little more than $35k, which will only continue to depreciate as the years go by. Also, this motor, now that it has a big cam, must be opened every 15k-20k miles to stay reliable. As I stated earlier, I am 23 and I only just started my career as an engineer. I began to realize that this car, despite it truly being my dream car, is literally going to stunt my financial growth from its infancy. Thus, before this car started becoming a 5-year liability, I made the tough decision of getting rid of it and paying off my existing car loan

I still enjoyed the time of owning my Z06. I met many cool individuals who all shared a similar passion of the engineering marvel that Chevy produced a decade and a half ago. However, I think based off perusing Facebook marketplace, it’s clear why this car is sold so cheap, with so low miles yet high number of owners. I think it’s a cycle that comes with owning a C6 Z06: getting initially enthralled by the motor, realizing the cost of owning such a motor, and selling the car prematurely after coming to the same conclusion as me above. The upfront price is low, but keeping the car is extraordinarily expensive and high maintenance especially if you drive it frequently.

I hope this anecdote helps those who are in a similar position to me age wise / finance wise. It might be tempting to buy that Z06 from Facebook marketplace, but you MUST come with the approach of what you are getting yourself into when buying a borderline racecar manufactured 14 years ago. This car WILL be expensive and high maintenance, and if you don’t have enough in your savings to take the blow of a valve drop, steer clear honestly.