Question on heads being milled multiple times
Question on heads being milled multiple times Ok guys I have RPM stage 3 heads on my LS6! I bent a exhaust Valve and the shp fixed it and told me the heads were milled .30. Then after they put everything back together they started the car and it bent another exhaust valve. Now they have taken the heads off and again they were milled .30!
What does that mean? Is that ok! Will that change the compression of the motor? Will I lose HP? What about clearence issues?
I don't understand any of this stuff! Did they do something wrong the first time that would cause the exhaust valve to get bent. By the way it was not the same valve they repaired. They are charging me for all the work on the last valve as well. I never even picked the car up. They told me after every thing was put back together that they now need to let it sit for a few hours for it to re seat. Is anyone in North Dallas, TX? I will buy you a 12 pack of beer if you come over and tell me if these guys screwed my car up.
What does that mean? Is that ok! Will that change the compression of the motor? Will I lose HP? What about clearence issues?
I don't understand any of this stuff! Did they do something wrong the first time that would cause the exhaust valve to get bent. By the way it was not the same valve they repaired. They are charging me for all the work on the last valve as well. I never even picked the car up. They told me after every thing was put back together that they now need to let it sit for a few hours for it to re seat. Is anyone in North Dallas, TX? I will buy you a 12 pack of beer if you come over and tell me if these guys screwed my car up.
Staging Lane
Joined: Jan 2007
Posts: 96
Likes: 0
From: Michigan
It's possible the shop screwed up the valve job. Milling the heads .030 twice is a lot. You might run into piston to valve clearance issues now and bend even more valves. They should've at least measured the piston to valve clearance before it was all said and done just to be safe. The shop should've turned the engine over by hand to make sure the valves were not touching. I wonder how bad the top of the piston is now. Did you see the piston's when they took the head off again? I would be concerned if it was my car. Oh and just to answer some of your questions- Yes, milling the heads will definately change the compression ratio. I had my stock ls1 heads milled .030 and it went from 10.1 to 10.8, just to give you an idea how much it changes. Head gaskets change the compression too by the way. Did they originally put the assembled heads on the car? Did you drive the car afterwards and thats when the valve went?
I just went through this with a set of ported heads that I bought. Found out that they were milled .080 after I installed them. I was told by the porter that I could still use 7.4" pushrods because he just cleaned them up. I ended up knicking the pistons on startup and detonated a piston because of the much higher compression. I was told that the most that you can take off is .060 without checking piston to valve clearance. .030 sounds like a lot for clean up.
No I had the heads on for last 30,000 miles and I missed a shift. That is how the first valve got bent. I took it to these guys to be fixed since it was close to my house. They had it all done early this week. They put everything back together and started it up. I was there when they started the car and it was running really bad/shaking. He has a lot of miss fire codes and said he would work on it so I left. The shop called about a hour later to tell me that it bent another exhaust valve. Today they got the heads back and put it back together but they would not start the car. They told me the machine shop told them it needed to sit for a while after all the fluids were put back in. I don't know if they checked the clearence for piston/valves or not. They told me they would start the car in the morning but now after seeing your post I think I really need someone to go with me to the shop in the morning. They want to charge me labor for both times they have taken the heads off. I have not complained up to this point because I have no idea what I would be talking about. Do you guys think I'm screwed!
Staging Lane
Joined: Jan 2007
Posts: 96
Likes: 0
From: Michigan
When you go pick up the car, before they start it, have them take the drive belt off and turn the motor over by hand-slowly, just to make sure the valves don't hit. You'd think they would know what the hell they are doing. What kind of shady shop is this? It sounds to me like they did a bad job of installing that particular valve or the problem lies with milling it .060. I feel bad for ya man. I think they messed up and your paying for their mistake. I would take a friend with you and complain big time. I don't see how it's your fault the second time. They did the work, they milled the heads and put them on. They should know better than to do that and not check piston to valve clearance. If I was in your shoes they would be paying for the second valve repair and any other damage that bending that valve may have caused. I can't imagine how those pistons look. I'm just sitting here getting more and more pissed and its not even my car.
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If they keep milling the head, you continue to lose P/V clearance. How do they know it bent another valve? Have they worked on LSx engines before? Ask them how tight the rockers were TQ'd. Were your pushrods checked to see if you bent any? Why are they milling the heads for a bent valve. HAve they taken both heads off and milled both? 
P.M. me your #.
P.M. me your #.
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TECH Resident
Joined: Jul 2005
Posts: 907
Likes: 1
From: NJ
Originally Posted by TXSilverV
They want to charge me labor for both times they have taken the heads off. I have not complained up to this point because I have no idea what I would be talking about. Do you guys think I'm screwed!
ask them if they checked the PTV after the first repair. when they say yes, ask them what were the clearance measurements. i bet they dont have it.
it is there fault that they bent the 2nd valve. my bet is that once they start it it will bend more valves or even worse because they milled it again.
Be prepared to get a lawyer
who is the tuner shop??
Yep the took both heads off. I know they did not check clearance the first time it was fixed because they said to me " It bent the exhaust valve again, were going to have to check for clearance now to see what the problem is". This shop came highly recomended from a couple of people. I wish some of you lived here so you could go with me to the shop. I scared over what damage is done now to this motor. It just seems like every time I get work done I get screwed or it's just bad work. I'm going back to school to learn how to do this work myself.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
I can tell you myself without even looking at it that if your heads are milled .060 on this 228/232 cam, there is no way it will fit without kissing the pistons.
To fix this you have 2 solutions:
1- get other heads
2- Flycut your pistons.
I would choose option 1, because it doesn't seem those guys can do anything and that much mill is too much and causes all kinds of issues.
To fix this you have 2 solutions:
1- get other heads
2- Flycut your pistons.
I would choose option 1, because it doesn't seem those guys can do anything and that much mill is too much and causes all kinds of issues.
My heads were measured against a stock head when I first got them. They were milled 0.060", then I had them milled 0.010" more b/c they had some small scratches from shipping and from sitting in a garage. Thats 0.070" total. Thank God for valve reliefs in forged pistons!! I have 4cc valve reliefs and a TREX...my rev limiter is set at 7200, its been there some and never gotten close to hitting a piston with a valve. You definitely need to flycut if you are gonna use those heads. As far as the intake, just make sure its down all the way. After you bolt it on, spray around it with starting fluid (ether) and if the idle stumbles any, wherever you sprayed is where its not down all the way. I had to do this with my LS6 intake and my new Fast 90, but eventually they bolted completely down.
