The case of the LS7 & LS9 Factory Heads and the Valve Drop Issue Whether you ordered a 2005-2013 Z06 or a 2009-2013 ZR1 Corvette brand new, bought one used or are currently looking to buy one, you might have heard about the notorious "valve drop issues".
What is it? To sum it up, there's many factors and theories. Heads machined improperly that resulted in valve guides not being seated concentrically in the head. The titanium coating on the valve stems wearing out too fast on the valve guides. Rockers allowing too much side play. The valve guides being too short for the longer valve stems. As such, once the stem snaps the valve drops onto the top of the piston. This results in at minimum minor damage to the heads and valve train. At most it is complete engine destruction from the oil pan to the plenum.
KaTech and Gwatney Performance lay it out quite well in these two links.
What cars does it affect? All 2005-2013 C6 Z06's having the LS7 heads and all 2009-2013 C6 ZR1's having the LS9 heads.
There's a lot of misinformation out there. Such as it only affects 06-08 C6 Z06's or 05-07's or 07-09's. It affects ALL of them. It is not a matter of if, it's a matter of when. Some of you will be lucky and it won't happen. Others will not be so lucky.
What do I do about it? 1.) Do nothing and just drive your car. You risk a minimum of $35K if you try to find another LS7 engine which is difficult because GM ceased production on these engines. That includes parts, labor and new heads. It's a gamble.
2.) Let your car sit and get new heads, intake and cam plus supporting hardware, gaskets, fluids and tune. $10K - $16K minimum for parts and labor depending on the shop.
3.) "Fix your heads". Ligenfelter and KaTech swear they've never had a failure of fixed heads. Others who had their heads fixed through other companies have reported a second failure.
4.) Go to YouTube and type in LS7 Valve Drop. There's plenty of videos talking about the issues. Watch them.
You can do nothing, you can fix your heads, you can replace your heads with fixed heads or you can get completely brand new aftermarket heads. That's 4 courses of action. Only YOU can decide what's best for you.
Tip: If you go with aftermarket heads, you can sell your factory LS7 heads to Gwatney Performance Inc for $1,500. Just message them on facebook, instagram or send them an email on their website and they'll tell you the process. If the heads are not modified and in good condition with intake valves intact, they'll pay you the full $1,500. Just be sure to mark your heads so you can identify them and take pics of the top, bottom (valves) and sides from multiple angles in really good lighting so you have a visual record of what you sent them.
Introduction Prior to purchasing this C6 Z06 I had six Ford Mustangs. A 91 GT, a 97 Cobra, an 02 GT, a 93 GT, an 03 Cobra and an 04 Mach 1). I was ready to play with something different this time. I would love to own a Mark-IV Supra but they are out of my price range. As are Ferarri's, late 60's Shelby GT500's, the 63-67 Stingray's and the newer C7 and C8 Corvettes. I love the 67-69 Camaro's but anything with a 427 cubic inch engine or bigger was also commanding an asking price out of my price range. I also knew that a 305, 327, 350, 383, 396 or a 400 cubic inch engine just wasn't going to scratch that itch. I wanted that 427 cubic inch engine. $50,000 was my budget. I wasn't going to settle this time but the C6 Z06 was finally in my price range.
I remember the first time I saw the C6 Z06 as a courier. I was making a delivery to a bank in Overland Park, KS in May of 2005 and there was a brand new white C6 Z06 parked in a spot in front of the bank. I looked at that car and fell in love. I'm going to have one, one day I said to myself. The C3, C4 and C5's have never appealed to me. It wasn't until 2013 when I saw a C2 Stingray at Bandimere Speedway doing a burnout in the burnout box that those started to grow on me but I doubt I'll ever be able to afford one. We can dream though right?
The Search The week before I bought my C6 Z06 I had been looking on all the classifieds sites. This car popped up on AutoList on a Sunday night. I was suspicious because it had been up for almost a month. I read the description carefully. One owner, garage kept, no accidents and almost all stock except for a new ATI harmonic balancer (great choice by the way) new serpentine belt and an MGW short throw shifter (yet another great choice). No tint, no gawdy ground effects, no painted interior trim pieces, no fender stripes, no racing stripes, no ricer wings and most importantly, that 427 cubic inch LS7 engine had those pretty red LS7 engine covers. The engine looked clean and completely stock. There was no evidence of a supercharger, turbo or nitrous under the hood. The engine bay was clean enough to eat dinner from. The wiring harnesses and the factory black tape wrap on the wire loom was intact and undisturbed. It wasn't worn, frazzled or ripped or faded. The paint, exterior and interior looked immaculate.
I wrestled with the decision to pursue this car or not for three days. That Wednesday, I contacted the salesman Jesse at Fusion Motorworks in Portland (PDX). There had been some mild interest in the car but nothing serious. Most people were too far away. I looked at the weather. The following Mon-Wed a high pressure ridge was encompassing the western part of the country. A perfect window to go get a car and drive it home. My mind started doing the logistics. The talks escalated with Jesse. I asked for a CarFax which he emailed over. It looked good. One owner, no accidents, no salvage or rebuilt title, nothing out of the ordinary reported. I requested a walk around video with the car starting up and running. As soon as the video came through, I knew I was buying it unless something serious showed up on the Inspection. The car was gorgeous and looked to be in great condition. Stock exhaust, stock engine, pretty interior. This is the one. I had Jesse email me a buyer's order.
Thursday came and I got online and submitted the loan application but by late afternoon I still hadn't heard anything about the loan so I called the bank and inquired. There were some technical difficulties that needed to be cleared up with a previous loan on a car that fell through. The new loan was approved contingent on clearing up the technicality the next morning.
I was at the bank early Friday morning. The loan officer got the old loan cancelled and issued a check for the new one. During the process Jesse started texting.
"Hannah, I have several people texting about the car.", "How many I asked?", "Six", he said. "Ok, give me another 20 minutes and I'll forward proof of funds". "Ok", he replied.
20 minutes later I paid a $1,000 non-refundable deposit via square. I sent Jesse a copy of the check front and back. An hour I booked my flight to Portland. I was so nervous and excited I booked the flight for the wrong Sunday. Thankfully, I cancelled it at no cost and re-booked. I then called a couple of Chevrolet dealerships in the area. Webb Chevrolet didn't do inspections but Carr Chevrolet was happy to do the inspection for me. I scheduled a 10:00 AM appointment. Jesse text me again that 9 more people had inquired about the car since I sent over the $1,000 deposit to hold the car. Wow! Talk about right time, right place!
Sunday night I caught an evening flight to Portland out of DIA. I watched Twister on the flight to kill the time. After retrieving my luggage, I took an uber and checked into a hotel just down the street from the dealership. I ate a hot pocket, downed a coke and went to bed. I must have woken up three times in a panic that I had overslept and missed out on the car.
The Inspection & The Purchase I got out of bed at 7:40 am and conducted my hygiene, packed my suitcase and checked out of the hotel at 8:35 and walked the 2 blocks to the dealership, rolling my luggage down the street. The sky was partially overcast with a damp, misty feel to it. But the day was rife with excitement! This might be one of the best Monday's to ever occur in my life.
It was Jesse's day off but the owner Josh was there and greeted me with a big smile and a handshake. Are you ready to see the car? I am. I set my suitcase along the wall and pulled my camera bag out and set it on the table. I then followed Josh to the back.
My mouth was wide open when I saw it. It also looked much smaller in person than I thought it would be. They sit incredibly low to the ground. The paint was beautiful. The interior was flawless. I walked around it several times. The car was gorgeous. A streamline butterfly! 🦋
After a few minutes of gawking at the Vette, I grabbed both of my cameras while Josh moved the car to a better location so I could take photos which I spent about 20 minutes doing.
Josh handed me the keys and I sat in the car for the first time. I attempted to start the car but nothing happened. Puzzled I checked the e-brake and put my foot on the brake and pushed the start button. Again nothing. Huh? I asked Josh how do I start this thing? He walked over and said did you push the clutch in? I turned bright red and felt so embarrassed. It's a manual transmission. Doh! 🤦🏼♀️ I had assumed it would start without pushing the clutch in and I'm not even sure why.
I pushed the clutch pedal in and hit the start button and the engine purred to life. The stock exhaust is incredibly quiet for a performance car but it still had a healthy growl to it. My heart was racing with exhilaration. I listened for any ticking, knocking or missing of the engine. I only heard the healthy rumble of pure American Muscle.
I shared my location with Josh via google maps and took the car to Carr Chevrolet in Beaverton, OR for a 10:00 AM inspection. The GM tech there went through the car with a fine tooth comb. I told him I'm looking for a reason NOT to buy the car. He put the car on a rack and raised it up and began. I sat in the waiting room while the inspection was ongoing. About 40 minutes later the service advisor had me follow him back to the shop so I could inspect the frame, suspension and undercarriage. I was looking for bent control arms, frame kinks, welds, pinched frame, frame damage and rusted/corroded frame rails and undercarriage components. These are big indicators a vehicle has been hit, wrecked, have flood damage or been drive in a harsh winter environment on salted roads. The underside was straight, clean and there were no leaks or drips. No corrosion or rust was present. There was the usual light oxidization underneath but that's typical. The tech also looked at the ecu history and said this car had never even popped so much as a single error code. He did note the clutch reservoir fluid was a little brown and low, the oil was a little low and the coolant was between the fill lines but still within spec, but he topped everything off for me as I had a 1,315 mile trip home. Tires were at 50% tread life and the big brake rotors were brand new at 12mm. We talked briefly about the inspection and he said the car looked immaculate for being 17 years old and having 34,900 miles on it. The charging system test (starter, alternator and battery) all passed with flying colors. I asked him if he saw any reason not to buy it. He said no, not at all. I paid the $236 inspection fee, sent Josh a text that I was on my way back and drove back to Fusion Motors.
I arrived back at Fusion and quickly pulled up the bottom door sill trim and checked underneath the carpet on the drivers side and then the passenger side. I was looking for signs of flood damage, mildew, mold and mud. The floorpan was immaculate. No sign of any moisture, not even the syrup from a spilled coke.
I went inside and signed paperwork and Josh endorsed the check, filled out my temp tag and handed over the other two keys fobs. We completed the paperwork and on Monday March 16th, 2026 at 12:30 PM PDT I took possession of my very first C6 Z06. It's Jetstream Blue, and it had 34,955 miles on it.
The Drive Home Josh went out and put my temp tag on and I loaded my suitcase into the rear hatch and put my camera bag in the passenger side floorboard. We shook hands and I got tin the car set the gps, adjusted the mirrors and off I went. Once on 84 East I set the cruise control. Seeing Mt. Hood for the first time was amazing! It's only 11,xxx feet but seeing it from sea level makes it look huge!
I stopped for fuel in Hood River, Oregon. I grabbed lunch at Taco Bell, then got back on the road.
I wasn't very happy the gas tank hadn't been filled up and the other fluids hadn't been topped off but whatever. Fusion Motorsports did make that right later, but I will keep the terms of what they did to make it right between us. I'm happy with how they made it right. I would also easily do business with them again. Josh and Jesse both have a lot of integrity that I haven't experienced with many other auto salesmen or dealerships. The gas and fluids got overlooked. It happens. It wasn't a dealbreaker, but I do think as a customer spending that kind of money the gas tank should be full, an oil change should have been done and the other fluids topped off at least. This is strictly my opinion.
The Z06 will need an oil change after the trip and I plan to have the clutch reservoir drained and filled with new fluid.
Going up Cabbage Patch was quite fun. The curves were rated for 45 mph and the Vette hugged the curves at 72 mph, never flinching, breaking traction or sliding out from under me, staying anchored and stable through each hairpin curve. The speed never bled off while ascending the grade or navigating the curves. What a beautifully engineered machine! I marveled to myself. The ride is comfortable and the suspension is incredible. You can feel the power just rippling under the surface. You can soft drive this car and enjoy a nice cruise. At the same time, that 427 is always ready to get down to business. The Heads Up Display is an interesting feature and I haven't decided if I like it or not yet. One thing I did notice is I don't particularly care for is the how the dash reflects on the windshield.
At the Love's in Baker City, OR I grabbed fuel and pulled the lower right fuse in the fuse box for the exhaust valve solenoids. The sound was much better with all four valves open on the rear exhaust.
I made fuel stops at a half tank each time. I finally stopped in Evanston, WY at the Pilot truck stop at 2 am because I couldn't keep my eyes open any longer and slept in the driver's seat for about 4 and half hours. Let's just say the Vette isn't real comfortable for sleeping in. Once I was awake, I topped off my fuel and continued back towards Denver. I paused at the off ramp for Elk Mountain and snapped a few photos of the Vette with the scenic background.
I made another stop in Laramie for fuel and a final stop in Bennett, CO to top off the Vette and grab some fruit and milk from the grocery store. I pulled into the driveway on St. Patrick's Day at 1:52 PM.
I calculated the trip totals. 1,315 miles in 24 hrs and 7 mins. My worst tank was 27 mpg and my best was 32 mpg.
New Perspectives Prior to purchasing the Vette, I knew a little bit about the valve guide and valve issue with the factory heads but not a whole lot. I was under the impression it only affected Z06's from 2008-2011. Mine was a 2009. I knew there was potentially some risk to drive the car across the country too, but I wasn't in a position to arrange transport and I only had this three day window to go get the car and I promised myself to keep the rpm's under 2500, no power shifting, no dropping gears and punching the accelerator, no hard driving and no high speed bursts. Not until we get the heads fixed. Patience.
The good news here is the car and I made it home in one piece safe and sound. I gradually accelerated to highway speed and I set the cruise at 6 over the speed limit. Let me tell you...it was incredibly difficult to resist the urge to drop the hammer. Patience, I told myself again (something I am not known for but am getting better at). I ran 76 mph through Oregon (70 mph limit) and 86 through Idaho, Utah and Wyoming (80 mph limit).
The day after I got home, I had a couple conversations with Rich at the Corvette Connection in Denver and then Tony Mamo at Motorsports about the issues with the valves and heads I learned it affects all the Z06's from 05-13 AND the ZR1's and it's not a matter of IF it will happen, but WHEN it will happen.
In hindsight it was an incredibly risky gamble on my part. If I had to do it all over again, I would not have driven it home. I'd have found a way to either go get it with my Tacoma and a trailer or have it shipped to my home. But fortunately for me, there were no issues on the way home. Now she sits in the garage under two car covers until I get new heads for it. I'm putting my deposit down on some Mamo Motorsports Stage 2 heads in Mid-May.
The Vette got a full hand wash and rinse with the pressure washer two days after getting it home. There was also some garage cleaning, re-organizing and shuffling of cars.
Potential Consequences & Solutions
Many people will have differing opinions on what I'm about to say next and that's ok. Based on my conversations with Rich and Tony the issue will eventually affect all these cars. The unknown seems to be when? The valve drop occurs at different times for each owner. I'm really curious as to why that is? I'm not an expert on this matter. I've read enough horror stories with the valve drops ranging from 3,600 miles up to 100,000+ miles. There's no rhyme or reason as to when. Tony @ Mamo Motorsports says there's multiple issues the lead to this. The machining process on the heads was flawed and the valve guide wasn't seated concentrically when it was installed in the heads. The rockers are also faulty and allow too much side play for the valve stem (valves should move up and down only, not side to side). The titanium coating is also an issue as it wears off and creates friction against the valve guides. Once the valve guide gets too loose, the valve stem snaps and drops the valve on top of the piston and bye bye engine.
One gentleman bought his Cyber Grey Z06 with 29,000 miles and drove it from Missouri to New Jersey with no issues. 45 days later, it dropped a valve and set him back $35K for another engine, labor and new heads. He encouraged me to get new heads ASAP.
This right here is why my car will sit until I get the new heads put on and get it tuned. I don't have $35K sitting around to get my car going again and I work 6 days a week anyhow. 3-4 months isn't a big deal. It'll go by fast. I will get to play with the car for part of August, all of September and part of October before I put it away for the winter. Patience and maturity is the test here.
Rich told me the heads can be fixed with "fixed factory heads". New bronze valve guides and valves. He told me he's never had anyone come back in with the same issue.
Tony says bronze valve guides aren't harder than the valve guides that GM used in the factory heads. By "fixing the factory heads" all you're doing is resetting the clock on the issue because you can't correct the concentricity issue with how the valve guides are seated when they were machined into the heads.
KaTech swears they've never had a set of fixed heads fail.
Each one of you can do whatever you want. At the end of the day, it's your car and your money. You need to do what's best for you, your finances and whatever it takes for you to have some peace of mind. It doesn't make you wrong or me right or vice versa. You don't need anyone's approval nor do I. No one can make this decision but each individual. Do your research, talk to professionals who deal with these cars. Then take the action you deem necessary.
Me? I'll be going with the aftermarket heads from Mamo Motorsports because I don't want to ever see or deal with this issue again. I don't want it lurking in my mind, overshadowing everything I do with the car and questioning if this issue is going to show itself again if I were to have the factory heads fixed. That's not a risk I am willing to take. I want to have confidence in my car and have lots of fun.
How do I find the car I'm looking for? Finding that perfect [to you] C6 Grand Sport, Z06 or ZR1 Corvette of your dreams can seem like an arduous, daunting and impossible task. Let's face the facts, these cars are becoming more and more difficult to find with lower miles, in pristine shape. And when you do find them, they want top dollar. Especially for rare colors like Inferno Orange, Atomic Orange, Daytona Sunset Orange, Supersonic Blue, Jetstream Blue, Nice Race Blue and my personal favorite LeMans Blue.
If you like black, white, red, silver and that awful yellow...you can find them all day long. But those other colors are what prompted me to write this and share it with those of you hoping to follow in my footsteps some day soon.
Each
and everyone one of us will have different criteria we are looking for.
Some things are deal breakers to us. Others are not. Our budgets will
dictate a lot of that criteria.
For me, under 40,000 miles,
stock LS7, no nitrous, superchargers or turbos. No racing stripes. Not
more than 2 owners. I would have considered an engine with the heads
done but I didn't want a big cam or aftermarket intake and not have the
red factory engine covers. I wanted Inferno Orange (to match my 2017
Tacoma), Atomic Orange, LeMans Blue (my top choice), Jet Stream Blue or
Cyber Grey. I would have accepted Victory Red or Monterey Red as a final resort.
Yellow was a definite no go for me. I can't
stand yellow houses or cars. Yuck. Black is so beautiful but so
difficult to keep clean and it attracts so much heat. My last two daily
drivers have been silver, so I wasn't interested in that color but it
does look very nice. White looks very clean all the time, but I'm just
not a fan of it. I need my car to have more character.
Facebook Marketplace Corvette Clubs & Corvette Classified Groups on Facebook Craigslist Offer Up App And word of mouth
Watch this Ultimate C6 Corvette Buyer's Guide.
Used Vehicle Inspection Checklist for the C6 Corvette
1.) Ask the vehicle be started with the COLD START PROCEDURE in your presence BEFORE having it moved outside in the best light possible.
Fluorescent lighting can make it hard to see things in the paint and
under the hood. A cold start is it's been shut off and cooled completely down for at least an hour maybe two. This gives you the opportunity to hear any squealing belts, knocking rods, other knocking sounds, tapping or banging that will alert you to any potential problems. (Special thanks to Hashem Wafa in the C6 Corvette 05-13 Official FB Group for the cold start tip!)
2.)
Turn on the headlights, foglights and emergency flashers. Approach the
vehicle from the front and do a general walkaround. You are looking for
the obvious. Leaking fluids, flat tires, broken windows, leaning to one
side or the other, the front end too low or high. Do all the lights
work? Check the high beams, low beams, flashers, then signals, marker
lights, taillights, reverse lights, brake lights and license plate
lights.
3.)
Start back at the front again and inspect the hood and front fenders
and bumper. Do the hood and fender lines all match up? Check for
blemishes, rock chips, scratches, gouges, mismatched paint, paint runs,
paint cracking, bubbles, dents, hail damage, impacts, rust and
corrosion.
4.)
Inspect the windshield. Any cracks, rock chips, scratches? Check the
window gaskets for rotting, dry rot and falling apart. Any rust runs
(which is a sign of a failing windshield gasket)? Check the condition of
the wipers.
5.)
Pop the hood and push it all the way up. Inspect the hood struts and
the engine bay. Is the engine clean? Is everything there? Are the engine
covers that say LS3 or LS7 present? Check for leaks, drips and runs.
Check the fluid levels. Is the brake fluid clear and full? Clutch
reservoir full and clear or low and dirty? Check the condition of the
serpentine belts. Check the oil levels and coolant levels. If you see a
milky substance in the coolant, this is indicative of head gasket or
engine problems. Walk away from the car. Inspect the wiring harness and
wire loom. On a cared for low mileage car, the engine harness should be
clean, mostly free of grease, the black shrink wrap should be intact and
undisturbed, no splices, fading or unraveled tape. Inspect the radiator
hoses. Inspect the condition of the hoodliner. Use a flashlight to
inspect the firewall for impacts, rust, corrosion and misalignment.
Start the engine and listen for tapping, knocking, missing, vacuum leaks
and any other abnormal noises. Turn on both the heater and a/c varying
the interior fan speeds and see if the lights dim or engine struggles or
idles roughly. Is the belt running smoothly and with no squealing or
fraying? Check the battery for corrosion or leaks and check the
connections for corroded ring terminals, exposed wires and frayed ends.
Some general oxidization on the ring terminals and battery terminals is
ok and expected. You can clean those up with sandpaper when you get
home. Check the paint inside the engine bay. It should typically have
paint with a dull finish. Check for overspray and unpainted, unmatched
surfaces and colors (primer black or grey on one side and the color code
of the car on another). This often indicates a wrecked car or at least a
damaged fender that was replaced. Is that a deal breaker? It would be
for me. But that's up to you. Check the radiator support for being
straight, painted and not leaning or dipping to one side. Make sure the
radiator fan cycles on and off while the engine is running and the hood
is open. Make sure you don't hear any weird pulley noises. Just a tip,
if the Harmonic Balancer hasn't been replaced already, it should be on
your post purchase to do list after you get it home. The factory one
tends to develop a wobble. An ATI 918620 Harmonic Balancer is high
quality and worth the coin. Once you're satisfied, close the hood and
let's move on. When you close the hood gently pull down on it from the
middle. Then walk to the passenger side and gently push down until it
latches. Then go to the driver side and do the same with that side. You
can also turn off the engine.
6.)
Let's go to the driver door. Check the fender liners for condition and
alignment. Examine how the door aligns with the fenders. Are the gaps
equal? Is everything in alignment. Do the lines match up? Inspect the
hinges. Inspect the door jambs on both sides of the door at the front
fender and rear quarter fender. Does the door open and close properly
with ease? Inspect the window glass on the driver door Is there any
rust, corrosion or bubbling along the door jambs and bottom door sills
and the door? Inspect the paint closely. Look at it in different angles.
Check for paint runs, scratches, gouges, discolored paint, dents, dings
and hail damage Check the door lip where the driver door meets the rear
quarter panel. This area is prone to cracking. I noticed the paint on
mine was cracked several days after I got home. Sigh. But it is a used
car with 36,000 miles on it. It's not a brand new car. Also check the
VIN sticker and ensure it matches the stamped VIN plate on the dash in
the front left corner by the windshield. Since it was over 5 days after I
purchased the car when I discovered it, I'm not saying anything to the
dealership.
7.)
Let's go to the driver rear quarter panel. You're looking for the same
imperfections as in Step 6. Make sure to carefully examine the lower
rocker panels in front of the tires. Mine have pitting and light rock
chips. I've been told this is normal due to the tires kicking up rocks
when accelerating and driving. Check the fender liners for proper
installation. 8.) Proceed to the Rear hatch/decklid. Inspect the left
side lip, right side lip and rear lip of the decklid. I found a crack on
mine on the rear left side of the decklid. The dealership is making
that right and taking care of it. I'm satisfied with their proposal but
I'll keep those terms to myself. Inspect the rear glass.
9.)
Check the rear bumper for alignment, mismatched paint (darker or
lighter than the rest of the car), scratches, gouges, etc. check the
diffuser and exhaust tips.
10.) Let's go to the passenger side rear quarter panel. You're looking for the same imperfections as in Step 7.
11.) Repeat Step 6 for the passenger door.
12.) Inspect the roof.
13.)
Inspect the interior. Do the seats go forward and backward easily? Do
the seat controls and lumbar adjustments all work? Do the seat heaters
work? Does the interior lighting work? A/C? Heat? Wipers? Horn? Radio?
Light switches? Turn signal indicators? Power mirrors and windows? Glove
box and center console open and close easily? Rips, tears or spills?
Steering wheel play loose? It should be firm and crisp. Start the car
and ensure the gauges all work. Are there any check engine lights on?
Any warning indicators or service engine soon lights? Check the oil
pressure readout and battery voltage. Inspect the interior door panels
and headliner. Ensure the seatbelts all fasten properly.
14.) Check all the tires for tread life and dry rot, uneven wear, sidewall integrity issues, holes and low air pressure.
15.)Test drive. Check for abnormalities, weird sounds, vibration, steering
issues, poor quality ride suspension and anything malfunctioning.
Alternate speeds and cruise along normally and then get on the throttle a
little bit. Do you hear any weird noises? Find a parking lot with a
wide open area, turn the car in a tight circle clockwise and listen for
any popping noises in the front steering. Now go counterclockwise. It
should be smooth with no popping or hopping or binding of the steering.
Is the clutch stiff? or soft? Do you smell any burning from the pressure
plate? How does the shifter feel? (An MGW short throw shifter will be a
bit notchy but this is normal). Test the brakes. Does the pedal go all
the way to the floor? Does the car stop easily and firmly? Or does it
struggle to slow down or stop?
16.)
I highly recommend having a GM Tech do an inspection also known as a PPI (Pre-Purchase Inspection). Check the codes
and see if the ECU history shows any type of codes that have popped in
the past. Any current codes? Have them put it on a rack and lift it up
and let you look at the undercarriage for corrosion, rust, bent
suspension parts, kinked, pinched, welded or repaired frame rails.
Another thing you want the GM Tech to do is look at the mileage on the
car's ECU and compare it to the odometer readout. Make sure a charging
system test is done on the battery, alternator and starter. The
Inspection is the last step you should do before you decide to buy the
car or not. If possible have an engine compression test done and a
leakdown test done. This will tell you the overall health of the engine.
Having it done at a dealership can cost $1,000. But a local auto repair
shop should be able to do it for substantially less. It's worth it to
have the peace of mind for your purchase. Because once you take
delivery...it is yours. Outside of a few laws in some states which vary,
you will have no recourse. Shop around and maybe find a 3rd party
extended warranty.
17.)
If you are driving the car home and it's more than 100 miles and the
heads have not been fixed, I would recommend you take it easy and
exercise restraint. Keep the rpm's under 2500. Nice, easy, steady and
gradual acceleration to highway speed and set your cruise control at 5-6
mph over the speed limit. Avoid dropping the hammer and avoid
aggressive power shifting (up or down) and stomping on the accelerator.
Avoid high speed bursts. Check your oil at every fuel stop. Your top
priority is to get the car home safely. Figure out your plan of action
with the heads and get it to the shop. Don't forget to swap out that
Harmonic Balancer too. Then get it tuned.
18.)
If you are having the car shipped, make sure to use a CLOSED CAR
TRAILER. Do not let some shipping company put your Corvette on an open
air trailer and haul it cross country. Rocks, pebbles and debris are
likely to hit your car while in transit. Don't do it. Make sure you tell
them in writing and verbally and that that language "Closed Car
Trailer" is on the agreement paperwork. Also have them send pics of the
car being loaded into an enclosed car trailer.
19.)
If you are taking a truck and trailer of your own to pick up the
vehicle, this is probably your best bet. Take 6 pieces of 2x6 to get it
up the ramps. These cars are super low and they will scrape. The 2x6's
help.
20.)
Get some driveway ramps to help get your Corvette into the driveway
without scraping. I was able to get mine in by going in at a 30° angle
and I went very slowly. Wal-Mart sells a pair for $32.
20.)
Now that you and the car are home, buy a car cover with a fleece lining
to protect that paint. Then purchase a plastic car cover with an
elastic band bottom to fit over the other car cover. The plastic cover
keeps dust and other things off the car cover with the fleece lining.
Keeping dust and other particles off the car when it is in the garage
will keep the paint nice for years to come and reduce how often you have
to wash it and detail it.
In Closing & With Perspective Keep
this in mind. You are buying a USED CAR. Unless it's never been driven
and stored in a climate controlled storage facility and wrapped in
plastic...it will NEVER be perfect or free of blemishes.
Before you go into this process, you need to KNOW what you can and will
accept and what you can't. Some of you will spend MONTHS to a YEAR AND A
HALF waiting for the right car.
Some
of you will find one with a few days to a few weeks. My wait was about a
month. I guess I got lucky and some very good timing.
All I can say is if you aren't patient you will only find disappointment. The wait is worth it in the end. Do NOT settle.
How do you tell if the heads have been done? If
you're considering buying one of these cars and the salesman at the
dealership doesn't know if the heads have been fixed, have him take
pictures of the passenger side heads. If the head bolts are silver, they
are GM Factory spec head bolts and the heads are not done. If they are
black and say ARP on the top of them, it is very likely your heads are
fixed. You can also look for any cnc engravings on the front end of the
heads. If they are factory heads, look on the passenger side heads on
the top left side. There will be an engraved number. GMXXXXXXXX (GM + 8
numbers).
C6 Grand Sport vs C6Z06 vs C6 ZR1 Many
buyers get scared off from the Z06 because of the heads and valve
issues. Guess what? The ZR1's have them too. Well the C6 Grand Sport has
its issues too. The rocker needle bearings are suspect in the heads. So
research that issue. But otherwise that engine is bulletproof and
blower friendly.
In
2015 I settled for a 2004 Ford Mach 1. I should have bought the Cobra. I
could have afforded the Cobra. I never came to love the Mach 1. It was
fun, I "liked it" but I never loved it. Don't settle.
The
C6 GS has a 6.2 LS3 engine. It's nothing compared to the 7.0 LS7 427
cubic inch engine. That power is raw. I had to have the 427. I wanted
the coveted Z06 badge and the performance package. I didn't settle this
time and I have zero regrets.
If
you're set on a C6 Z06, then find one with heads already done or budget
some extra cash to do the heads, fluids (oil/coolant) and head gaskets
plus a tune and go find your car. Don't let these issues scare you off.
I will at some point create a C6 Corvette Specific Inspection Form that you can use to check off things as you go or give to whomever does your Inspection.
I'm
sure I've forgotten something on here. So if you see something I
missed, leave a reply in the comments below and I'll edit the posting
and give you credit at the bottom (below here).
Special thanks to Hashem Wafa (Pre-Purpose Inspection and Cold Start Tips) and Todd Worley (Texas Hot Rides recommendation) for their contributions to this write up.
Current Modifications MGW Short Throw Shifter ATI Harmonic Balancer w/ New Serpentine Belt Vette Lights Plug 'N Play Sequential Turn Signal Kit LED Interior Bulb Upgrade LED Reverse Light/License Plate Bulb Upgrade Smoked Side Marker Lenses w/ Laser LED's (Front/Rear) LED Headlight/Fog Light/Turn Signal Upgrade Corvette American Flag Hood and Rear End Badges Corvette Rear Bumper American Flag Theme Letter Inserts RPI CAGS 1-4 Shift Skip Eliminator Improved Racing Oil Catch Can Lingenfelter 180° Thermostat
Upcoming Modifications
Performance Mods - Round 1 Mamo Motorsports Stage 2 Ported Heads (Ordered 4/08/2026) 265 cc | 11.65:1 compression | Pac 1222x springs | CNC Milled and Ported | Hand Polished 2.205 Hollow Stem Intake Valves | 1.600 Exhaust Valves Trick Flow Blank Head Castings | Custom Valve Work Clearanced
Comp Cams Stage 2 Camshaft 231/245 (Ordered 4/08/2026) Lift to remain confidential at the request of Mamo Motorsports
Bosch 72 lb. Fuel Injectors (Ordered 4/23/2026) YT Ultralite Rockers (Ordered 4/08/2026) Johnson Link Bar Performance Lifters (Ordered 4/08/2026) Manton Pushrods (Ordered 4/23/2026: Pending Measurement) Rollmaster Red Series Timing Chain Set (Ordered 4/23/2026) MSD Red Letter Intake Manifold (Ordered 4/08/2026) ARP 134-3610 Head Studs (Ordered 4/23/2026) Cometic Steel Head Gaskets (Ordered 4/8/2026) Dyno Tune (This combination should make 575 rwhp on 91/93 Octane Pump Gas)
Performance Mods - Round 2 Mamo Motorsports 103mm Ported Throttle Body Aftermarket Exhaust System (To Be Determined)Mild2Wild Ram Air CAI American Racing Headers High Performance Clutch Upgraded Torque Tube & Bearing Kit High Performance Dual Fuel Pumps Dyno Tune (These mods should get us to 630 rwhp on 91/93 Octane Pump Gas)
