jbvaldez

Dropped Valve.


31K miles

Mods:Cam, Patriot Springs, bronze valve guides, SS exhaust Valves. Pulled the heads. Driver side head.

amdoverclocker

How long ago did you re-do the heads? Did you do the work or a shop?

jbvaldez

Did the heads in July of 2012 with 23K on the engine. Work was done in Dallas at a shop. It is the intake valve that snapped. I am tracking that this is rare for the LS7 because it is usually the exhaust valve that fails. If I am wrong someone please tell me. I could not find the rest of the valve stem, it might show up in the exhaust on further disassembly.

Top of the piston is gouged so I will have to pull the block. I am thankful the block was not damaged.

Landru

Sorry to hear, lousy break, you seemed to have been proactive towards eliminating the issue and here you are.

Is the motor shot?
To me it appears valve head stayed in the head, though can't tell what else may have been inhaled. Be a stroke of luck if the thing can be saved.

Really feeling your pain.
What's next?

bjmsam

Why were the heads originally repaired? It has been 31K since that work, or only 8K? Was the geometry checked? Were the bronze guides installed for the intake valves or only the exhaust valves? Were the stock titanium intake valves polished before reuse? How aggressive is the cam? What type of oil do you use and what is your warm-up procedure?

jbvaldez

1. I am not sure if the intake valve guides were changed to bronze. I am trying to determine if it was done on the intake. I'll post picture maybe some one can tell me if they are bronze or not.

2. Not sure if the intake valves were polished.

3. cam 110+3 240/249 648/648

4. use recommended oil per owners manual

5. Warm up: never go over 3K rpm when the oil is under 180 degrees.

6. Bought car with with 8K on the engine.

7. Did a cam 110+3 240/249 648/648 along with the springs and ARH headers at a Dallas Shop with 10K on the engine.

8. Had the SS Valves and Bronze guides done @ 23K because I was moving to Germany and wanted to have the work done in the US as it is much cheaper in the US vs Germany and I wanted the extra piece of mind.

jbvaldez

Looks like the top of the piston was smacked around, but I think the block is undamaged... I am hoping I was lucky. Still looking for the rest of the valve stem. I think I'll find it in the exhaust.

Taking the car apart on jack stands outside. Sucks in Germany in the winter.

Whats next? Planning it all out now. Gotta get it together because I am moving to Italy in August. Looking to stay NA, stock heads ported and milled .030, stock intake valves, Ti exhaust valves, bronze guides, and PSI beehive springs.

MTIRC6Z

Are you sure you didn't have a problem with the valve spring?

Check the other 7 intake guides (heck check the exhaust guides too) and IF the intake guides are not worn badly, I'd take a much closer 'look' at the valve springs.

Cheers, Paul.

jbvaldez

Here is a close up of the guide. I am thinking this a PM guide.

I really dont know if the valve was polished. Have not been to the shop. Gotta replace the piston, looks like no damage was done to the cylinder walls. I'll get a pic tomorrow as it is dark outside.

As far as a shop goes I am pretty much limited to dealerships near me in Baumholder that can do the work. Cost 450 Euro to tow it back from Graf (renting a van and trailer) . Cost at a dealership for this work would be insane in Germany, so much so I'd rather wrench in the cold on my days off.

jbvaldez

Here is a picture of the top of the spring. inner and outer coils apear not to be broken. Not sure what I am looking at here on the top. Seems as if the rocker indented into the retainer.

jbvaldez

Another picture of the guide and bottom of the valve head.

blkbrd69

Sorry for your loss. looks like you have a bunch of work ahead of you.

Is it me or does the top of that valve retainer look like it has a huge wear mark from the rocker? Missing lash cap?

Enlarged the photo. It appears the complete valve tip and retainer was worn away. This is not a valve issue but an assembly issue. There have been a few cases of shops leaving lash caps off. Normally you would here it before it got to this point, but if the lifter was setup with bunches of preload it may have been silent till the end?

What RPM did this happen at?

Looks like it was a ticking time bomb missing the intake lash cap. If any others are missing you may want to have a little talk with the shop that did the work?

GeneSch

Cant see the guide with the Valve seal on it. Pope the seal off the guide.

I bet the retainer failed alowing the valve to bouce between the rocker and the pistion untill it feel enough the enter the cylinder all the way and snapped the head off. Broke the stem in a few sponts and sent it on its way. You can see wheere the valve hammered on the port over and over leaving rings.

RamAir972003

What shop did the work.....maybe valve springs locks retainer who knows, also if the shop told you bronze guides those are not bronze guides...

GeneSch

Check to see if any of the other intake valves are starting to go or if any are missing the caps. If so I'd try and go after the place that did the work.

jbvaldez

Appreciate everyone's input . Looks like a lash cap either came off or was not installed. Knowing the why is important. I" ll get some pictures of the block/piston later today when ithe sun comes up. I would be interested to hear some thoughts on what exactly to do next. Where is the best place to order a shop manual?

Rene_Z06

Recommended shops with Corvette and LS engine experience in germany near to you:

www.acp-euskirchen.de/
http://www.corvetteproject.de/ (Werner, i personally count on him 100%)

Rebuild heads or new heads via:

http://www.coolchevy-raceparts.com (Austria)

Heinz cooperates closely with Richard from WCCH. He will do my heads in spring.

Cheers from Frankfurt

MTIRC6Z

There is no way for a lash cap to come off during 'normal' operation, they might pop off IF a rocker or valve spring breaks. Other than that lash caps only come off when human beings removed them.

Also, without a lash cap the valve stem will be about .050" shorter than it should be, thus meaning with a stock length push rod that lifter will have little or no preload.

Cheers, Paul.

jbvaldez

Top of piston

blkbrd69

Cant picture a way for one to pop off in service, they have quite a lip on them. That one was missing for quite a while.

Wish you had a Blackstone report?

Not quite true on the preload. I have gone from .125" to .075" preload with no change in lifter noise. So with a cam, milled heads, stock pushrods and no lash cap "the preload" may have been perfect?