hapnermw

After 30K+ miles and about 30 HPDE track days I decided it was time to rebuild the engine in my early 2007 Z06.

The car has:

• Katech torquer 110 cam
• PSI Beehive Springs and Katech retainers
• CHE upgraded rockers
• C5R Timing Chain
• Lingenfelter Sump
• DeWitts Radiator and 160 degree TStat
• Ported Throttle Body and Intake Manifold
• Melrose Jet Hot Ceramic Coated Headers and X-Pipe
• Halltech KillerBee Intake
• RPM upgraded and micro polished Transmission and Differential with GForce Drive Shafts
• Pfadt Spherical Bearings
• Spherical Rod Ends
• ZR1 Hubs
• Stoptech BBK with Cobalt XR2 Pads
• Hardbar/Penske 8700 Triple Adjustable Shocks with Dual Hypercoil Springs and Spherical Mounts
• Hardbar Camber Kit
• Hardbar Upper A Arm Studs
• Hardbar Harness Bar
• Hardbar Lap Belt Bar
• Hardbar Fire Extinguisher Bracket
• Teamtech Jet Pilot Harnesses with HMS Shoulder Belt Grommets
• MGW Shifter
• Elite Catch Can

The rebuild adds:

• Callies Compstar Crankshaft
• Callies Compstart H-Beam Rods
• Diamond Racing Pistons
• Callies Balancing
• Katech Red (High Pressure and Flow) Oil Pump
• ARP Main and Head studs
• WCCH Ported and .020 Milled Heads
• Manley LS7 Severe Duty SS Exhaust Valves
• PRC .675 Double Springs Kit
• CHE Valve Guides for any that are out of spec
• Morel High RPM Lifters
• ATI 10% Underdrive Super Damper
• Hinson Urethane Motor Mounts
• LS9R Clutch

The objective of this is to create as reliable an LS7 as possible while achieving as much NAS power under the curve as possible for combined street/track use.

Since this car has seen a fair amount of 1G+ left hand sweeper action at Laguna Seca and Thunderhill on R Compound tires and the state of its engine indicates that it has not experienced any bottom end oil starvation, the extended capacity sump appears to have done its job.

WCCH hasn't evaluated the valve guide wear yet. It will be interesting to see what they find.

Some interesting items have surfaced.

One lifter was in the process of coming apart. As the picture shows the snap ring was bent and had left home - the other pieces were still in the lifter but likely would have departed in the near future. Possibly the snap ring had been improperly fitted from new.
http://gallery.me.com/hapnermw#10000...&bgcolor=black

There were two pistons that had ring gaps almost aligned. This is a picture of the worst - cylinder one. It is hard to believe that the rings could have rotated on their own this much. Possibly they were not properly positioned at assembly.
http://gallery.me.com/hapnermw#100004/photo-1

It is interesting to compare the quality of manufacture of the stock and Callies crankshaft. The Callies has precisely edged counterweights - stock counterweights are pretty rough. This likely isn't a functional problem but I had expected something better. This also shows the quality that Callies delivers, even on their lowest priced crankshaft.
http://gallery.me.com/hapnermw#10000...&bgcolor=black

There were a few light scuffs on the rod bearings but in general all looked good.

The internal oil pump surfaces had begun to scuff. The bottom surface was the worst with noticeable scuffing. It likely had a lot of life left; however, there definitely seems to be some form of design issue with the stock pump causing premature surface scuffing. Katech's upgraded pump has reconfigured the drive in a way that looks to minimize this type of wear.

tjwong

If I were you and only because you want a "as reliable" as can be LS7. I would choose a set of Manley Nextek springs or the Ferrrea spring sets. Both are much more money but in the scheme of things its a lot cheaper than another rebuild, or engine block if a valve drops at high RPM because a spring breaks. All springs can break, but there has been more instances of PRCs and other 'cheaper" imported springs going away than the Ferrea or Manley or PAC brands.

Also if you think that thei Callies Compstar crank looks good, you should check out the Callies Dragon Slayer line or their Magnum line of cranks. Now those pieces are a work of art.

dollarbill

A+ on the post.

Excellent information and a well thought out rebuild plan.

Spending on a project like this can be endless but you have done a nice job with your selection of parts.

Good luck and enjoy the results.

Autobahn93

great timing to up-grade before something major happens and sounds like a solid built for the track. The engine going into my car is currently rebuilt with stronger parts as well like forged pistons, springs, ss valves, rockers, valve guides etc.
However, your car has so many additional nice features for the track I am jealous about
How do you like the pfadt shpericals for street driving? Do they make a lot of noises and need any maintenance? I would love to have a more direct handling.

hapnermw

TJ, thanks for the spring advice. I'm aware there is some tradeoff. The PRC's appear to be the best 'cheap' springs and there was a budget for this. At least they are doubles.

I would have kept the PSI springs; however, they don't have the strength to control the heavier exhaust valves. The stock sodium valves are 71 gm. and the Manley valves are 103 gm.

hapnermw

There is no noise from the sphericals and I don't find them to be an issue for the street. You definitely feel Bots Dots more. If the roads were rougher in my area possibly I would have a different opinion. There is no maintenance. I just power wash around them after track days. Pfadt sells inexpensive replacement bearing kits but I haven't worn out any so far. In every way, they are much better than the poly bushings I had previously.

I did have a rattle in a rear quarter that occurred over certain types of bumps but I wasn't able to track down its source. About a year later, I started to get a strange vibration at speed on the track. It turned out that one upper A arm spherical had a lot of play. When that was replaced, the rattle disappeared. It appears the bearing was defective from the start.

thesubfloor

I'd also strongly advise against the PRC .675 springs as I had all kinds of problems with them breaking at the dragstrip. As soon as I changed over to the PAC-1521s I haven't had an issue since.

hapnermw

Thanks, I had seen the thread where your problem with the PRC's was discussed. Clearly, your valve train was breaking the outer spring consistently.

In the thread, the PRC .675 is stated to be less tolerant of certain valve train 'instabilities' due to its use of Extra High Tensile Chrome Silicon Wire for extended lifetime. The thread mentions the intent to do a follow up spintron test. Do you know if this was done?

http://forums.corvetteforum.com/c6-z...-lift-cam.html

Given the quality/design of this build's other valve train components, I'm definitely not expecting to have the same problem.

Unfortunately, the number of spintron/optron validated LS7 valve trains with SS exhaust valves seems to be limited.

Since there is a growing number of people replacing their sodium exhaust valves, this is something that LS7 cam vendors need to fix.

69dodgecharger

While I understand the aftermarket pistons and crank why not reuse the stock titanium rods?

hapnermw

While there is nothing wrong with the stock rods I decided to replace them for two reasons.

First, the mechanic doing my build has built many racing engines and he preferred the Compstar rods. He felt the weight tradeoff was worth their increased reliability. Sintered titanium rods with relatively rough forgings are not as bullet proof as the Compstar rods. The extra weight likely reduces acceleration a bit but it doesn't affect the rev limit.

Second, it was more convenient to get the complete rotating assembly from Callies since they include balancing in the cost. If I had kept the stock rods I would still need to rebush them (as Katech does) and then do the balancing locally.

hapnermw

Richard at WCCH measured the valve guides and found the following:

The exhaust valve guide wear aligned with the other LS7 heads he has seen - all were significantly out of spec and required replacement.

The intake valve guide issues align with a pattern he has been seeing - all but two were oddly cone shaped. The cone is circular so it doesn't correspond to a typical wear pattern. It may be due to manufacturing tolerance issues. Richard said he has seen guides with this issue in low mileage stock heads. I'm having all replaced.

This engine was stock for about 15K miles when it had a Katech Torquer cam and PSI springs installed. There is nothing in its history to account for this level of valve guide wear.

So on this engine there was a lifter falling apart, two pistons with ring gaps aligned, severe exhaust valve guide wear and oddly out-of-spec intake valve guides. At least it held together long enough to get these fixed ...

Possibly there will be someone brave enough to keep their sodium exhaust valves with new valve guides so they can report back on how this combination wears.

I hope this info is useful for those on the fence about rebuilding their LS7.

ramairws6

I had all the above issues with my stock valves and guides on about 5000 miles worth of hard abuse. Richard replaced all the guides on the exhaust side but the Intakes were fine. New stainless valves and dual springs and off we go

jgaches

What intake vales are you going to run, and whats their weight? Great thread.

hapnermw

Stock titanium intake valves - 76 gms.