|11-10-2006, 05:54 PM||#1|
The stick man
Drives: 2004 GTO - C5 'vert - SRX
Join Date: Jul 2006
Location: In the new shop... working 24/7
LSX owners: AFR Cylinder Head Owners
I know this isn't Gen5 related but it is quite important to existing LSX owners...
It has come to our attention that some time ago we received a batch of valves from our supplier (8 mm LS1) that the tips were not hardened to the proper Rockwell scale. Over the course of time this will lead to the tip eroding ultimately creating lash (play) between the worn tips and the rocker arms. As this situation progress’s further, the audible ticking noise will get louder and the wear will accelerate faster from the pounding of the rocker arm on the valve tip. If left completely unchecked, it could cause a valve to drop (worst case scenario) but the clacking noise would be very audible if the damage had progressed that far and it’s extremely unlikely anyone would drive it that long without noticing. Take note that depending on how loud your exhaust is and how far the problem may have progressed, you may or may not hear it from the driver’s seat. I would encourage anyone who’s reading this and has purchased our heads to listen to the engine running with the hood open. Note also that some cams with more aggressive lobes (XER, LSK, etc.) will always have more valve train noise than a stock cam….what you are listening for is abnormally loud clacking and a noise that seems more isolated to possibly only one or a few bad valves.
The good news is we have shipped over 1000 sets of LS1’s in the last year or two and this problem currently represents approximately 1% of our sold and delivered units, however, till we get a better handle from our supplier on how many valves they may have sent us that way (which we are working on), we felt it best to be upfront with you guys in the event we can help prevent any serious engine damage by alerting you to a potential problem ahead of time. Understand that this letter isn’t meant to induce panic and hopefully you never experience any issues (needless to say it would have been far easier to bury our head in the sand in the hopes this is very isolated and goes away), but management felt it would be best handled by being pro-active and sharing the information with all of you who stepped up and bought our product (regardless of whether you may or may not have some issues now or down the road that need to be corrected). We are also aware that one of our competitors recently reported something similar regarding tip wear, but in our situation its not related to geometry and the few people that have had an issue had both stock and aftermarket roller rockers. These are simply coincidental and un-related occurrences.
In the event you are experiencing any issues please contact AFR directly…. note that in one case the damage took as long as 8000 miles to be pronounced enough for our customers/shops to look into the abnormal tapping noises emitting from the valve train. A few happened much faster than that which IMO is more likely. Currently, we are handling each situation on a case by case basis and will continue to speak with our manufacturer (who also builds valves for OEM applications) to try and get a better idea of how much help they will be willing to provide.
As I learn more I will be passing it along to you….in the meantime I advise you give the valve train a quick listen and if you’ve got the time, tools, and ability, removing both valve covers to take a closer look at your valve stem tips certainly wouldn’t be a bad idea. A bad one will have an arc ground in it from the rocker wiping across it.
We hope this info helps some of you to avoid any potential problems….
Feel free to contact myself or anyone in the Sales/Technical Dept. by dialing (661)257-8124
Please leave a message in the event you can’t reach a live person and someone will get back to you shortly
AFR Sales / R&D Mgr.