Nowanker

Working on your own car is one thing, trying to not lose money running a repair shop is another... it's a thankless task.
My own car? I might reuse them.

Unreal

Reusing an oring designed to be reused isn't crazy or outside of the norm. That is like putting tires back on if the wheels come off. The intake manifold seals are nothing but orings, not an actual gasket and are completely reusable, just like the TB oring, or valve cover orings and many others on the car.

~STOLEN~

+1
This is what I've done in the past as well. When taken off and inspected and isn't damaged or cracked. Ive put them back on without issues.

Nowanker

Again, it's the difference between doing a job for a paying customer, and accepting all the liability that goes with it, and working on your own car.
GM sez replace them. If I do the job without replacing them, then I accept the responsibility for doing the job over for free if they fail.
What on earth would be my motivation to do that?
And if I did write the estimate suggesting I would reuse them, I'd surely get some wise *** posting up about me planning to cut corners on his repair.

Unreal

I don't know of a single shop that replaces them. I don't know if GM even replaces them per the book. They are a reusable item. Inspect and use if not damaged.

Might as well say you need new tires if you take the wheels off or something silly like that.

1972bluelt1

Unreal,

Not that I needed it, but thanks for reminding why I do my own work.

Unreal

Yah, it is sobering when you see quotes. I have an easy $60-70k in parts in my car to make a nice reliable 1100+rwhp, but if I had to pay labor, omg, it would be crazy.

z06801

I been on here lately (the C6z06 thread) want to get one for a driver as I have just sold my 911turbo. I've been just reading about the head issues and it occurred to me that I have what I think are fairly stock LS7 heads on my 434ci Ls2 purchased from scoggin dickey so instead of starting another head thread just thought I would ask here if those are in danger and should be checked out? Motor is in a C5Z06 NASA ST1 probably less than 40 hours on the motor.

~STOLEN~

@ 40 hrs who knows, depends on the type of driving i guess LOL id hate to think guides would go out that fast.
do you have access to the build sheet or could you call and figure out at least what guides are in the heads? you said "fairly"stock ls7 heads. find out for sure

or pull a valve cover and a spring and do a check

z06801

That would be all track, time trials and W2W racing. So I guess about as hard as it can be run I'll check them before we start running again in march. Glad I started reading over here thanks for the info everybody!

Racingswh

Yes it should be checked out to be safe. If it were mine I would have them checked for sure.

All the LS7 engines I have seen let go from dropped valves were being used in road racing environments.

2 seasons ago I was in the hotel lobby after dinner having a conversation with another guy and he was asking me how to get the heads addressed and was going to start the process after the weekend. The next morning his LS7 dropped a valve, ventilated the block and put about 10 of us at risk coating the track online with oil and coolant.

Mordeth

When a car/engine is driven/raced in a road racing environment the time scales of how long parts last change dramatically. So in racing it is duty cycle that matters. I know guys with 800+ whp street cars that are built right and last 10s of thousands of street miles. They think they abuse them because they blast a few freeways or a few stop lights every day, but this is NOTHING like an actual racing environment. Not even close. Period. Put them on a race track and run them WOT for an hour or so they bust quickly. Heat kills things, as does duty cycle, as does sub-par parts, as does certain kinds of abuse.

Duty cycle is essentially power over time. How much power you make and for how long you make it. An engine can go hundreds of thousands of miles on the street (and even driven hard), but that same engine might have to be rebuilt in 30-40 hours of track use. Every single engine that is run in the 24 hours of Lemans is completely rebuild after the race - period. Any component can only function at max power for a finite amount of time. 40 hours of track use and things will in fact start to wear and give way. I typically need a partial rebuild at the 25 hour mark and a full rebuild at the 50-60 hour mark. Cast pistons will be lucky to last this long. Guides wear. Parts rub together. Stuff heats up and cools, heats up and cools and then weaken. Clutch wears. Transmission. Etc etc. **** just breaks.

Almost every part on your car is a wear item (including even fixed heads), and it is the duty cycle that ultimately determines how long it functions optimally. So at 40 hours of hard track use a full inspection is in order. Valve springs needs to be checked. Valves/guides need to be checked. Rockers inspected. Gaskets replaced. Compression/leak down needs to be done. Alternator/starter/battery tested. Plugs/wires replaced. Clutch inspected. Full nuts/bolts. Every single fluid in the car flushed (brakes, clutch, oil, diff fluid, trans fluid, power steering fluid etc). The list goes on. 40 hours of track use is a fair amount of duty cycle.

z06801

I totally agree the abuse a road race motor takes is off the scale, this 434 is a fully forged motor. But was built with a fairy mellow cam and compression only makes 508RWHP which is all I can and stay in ST1. Compression test less than 3hours of use ago was still really good but didn't do anything to the heads could be my weak point for sure. Car as also runs a ARE 3 gal drysump. Hoping to get one more season from motor. I'll definitely get the heads gone though before the season starts.

Mordeth

I think you will get another season out of her. At a minimum I would be wiggling some valves and see what happens. It isn't a perfect test but it will tell you if there is a serious problem waiting to grenade your engine. I would also check the springs. They can weaken over time, especially when subjected to severe duty cycle. Both of these are fairly easy to check and are things that lead to catastrophic failure if not caught in time. I would also do a leak down. Also simple and quick and can detect problems before they become catastrophic, as well as give you an idea of the health of things you can't see. I routinely check everything that I know can cause catastrophe. Especially if it is easy to check and even more especially if it is a known, likely faulty part (like LS7 head guides/valves).

It is good that she is mildly cammed with not high compression. This effectively gives you more duty cycle out of components, especially the pistons and valve train.

Another thing is to simply listen to your engine. You should know how it sounds when healthy. And it will usually tell you when it isn't. Valve train stability is paramount in a road race car.