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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Got it back together and everything is running good. Texas Speed was very quick and responsive.
Wow, got my LB motor from TSP with the the 265 heads but not milled, i think. But with the harden tips. as what you were saying in your first post. I am still waiting on parts, an money spent that i dont have, to get her on the road. ( NO THANKS TO GM)my TSP LB, is still sitting in my garage, Parts ordered so far from Maryland Speed are: kooks headers, halltech 103, tr6 plugs, slp 160 stat. fast 102, fast oem fuel rails, an ss hardware. OEM engine oil cooler, Dont know if i should change out the oem clutch i just replaced, at 30000 mi, it has about 5000 miles on it now. Off hand what other things (be sides a f---in hole in my head ) I should put into my 07 Z06.
I think these specifics valves had issues, not all hardened tip Ti valves that TSP ever used. From what I understand they've used several different brands of Ti valves over the years.
Originally Posted by richie427
Wow, got my LB motor from TSP with the the 265 heads but not milled, i think. But with the harden tips. as what you were saying in your first post. I am still waiting on parts, an money spent that i dont have, to get her on the road. ( NO THANKS TO GM)my TSP LB, is still sitting in my garage, Parts ordered so far from Maryland Speed are: kooks headers, halltech 103, tr6 plugs, slp 160 stat. fast 102, fast oem fuel rails, an ss hardware. OEM engine oil cooler, Dont know if i should change out the oem clutch i just replaced, at 30000 mi, it has about 5000 miles on it now. Off hand what other things (be sides a f---in hole in my head ) I should put into my 07 Z06.
How did you discover them? Did the tips break off?
I was assembling a long block for my buddy and when I was about to install the head (used from his last set up) I noticed one of his intake valves looked like the one at the beginning of this post. I then decided to take a look at mine and while they arent as bad they are showing signs of wear. I guess I just noticed it before it got bad.
Bump from the dead but wanted to see if anyone had this happen with there PRC heads, I'm debating on getting a new one from them or moving on to a different company seeing as there has been some issues with them dropping valves. I'd like to figure out why this happened before I move to the next step. Piston to valve clearance was right around .110 for the intake when installed. Stock redline.
So, who was the 'expert' who installed the heads without the lash caps on the titanium valves ?
I remember seeing another thread here where the same thing happened to someone else with titanium valves and no lash caps ... lots of damage to that poor LS7
I checked that all lash caps were on prior to installing the rockers and all the other valves still have there lash caps in place. No signs of wear at the top of the valve and retainer was still in good condition
For anyone that's curious - this is what the hardened tips look like prior to being pressed into the valve. In all of these situations it looks like the knurled section separated from the top hat portion via a clean break/crack.
Personally I think this is a poor design. The load bearing surface (in compression) of the titanium valve stem is greatly reduced when it is counterbored for the knurled portion of the insert. Then even if machining tolerances are held to tight tolerances pressing the insert into the weakened stem could cause micro fractures in the titanium. Then the side loading (or shear) capacity is also reduced because it relies on the smaller diameter of the knurled section of the insert. Compare this to the GM design. Combine this with high open spring pressures and non roller tip rockers and I think durability goes down.
I think the real fix for all these LS7 valve problems would be to install quality SS hollow stem intake valves and SS solid stem exhaust valves once the valve guides were machined concentric with the valve seat.
I think the real fix for all these LS7 valve problems would be to install quality SS hollow stem intake valves and SS solid stem exhaust valves once the valve guides were machined concentric with the valve seat.
Just my opinion ...
With the added weight of the intake what would be needed wrt springs & then lifters?
I think the real fix for all these LS7 valve problems would be to install quality SS hollow stem intake valves and SS solid stem exhaust valves once the valve guides were machined concentric with the valve seat.
Just my opinion ...
Yup - but then you have a lot of weight to control at the redline.
09-20-2014, 07:16 PM
