MTI Stage 2 LS6 & X1 clearance problems! Pro's inside please!
11-14-2003, 11:13 AM
#1
MTI Stage 2 LS6 & X1 clearance problems! Pro's inside please! I pulled the head off of my car to send back to MTI to fix a small seepage problem in the #7 intake runner. Upon removal of the head I noticed that every single one of the pistons had a small indention from a valve. I didnt have the time before I left on vacation to really inspect the situation. But when I got back on monday I started checking things out.
At first I figured that it was floating an exausht valve that caused the issue. BUT since the car has a rev limiter that was programmed by MTI wouldnt that keep the valves from floating? And if it was an intake valve that was hitting then it was definatley a clearence issue. Granted, I knew prior to getting into the X1 package that the P2V was very tight in there, but everyone (MTI included) said that there was still plenty of space.
Last night was the first time I really got a chance to sit and inspect the vlaves and the piston. At first I was hoping that the mark on the piston was just a nick in carbon build up. Well, its not. It is the valve has definatly made contaact with the face of the piston. However it is a VERY slight nick. And here is the problem. It is the INTAKE VALVE, not the exauhst. which would mean a CLEARENCE issue. However slight the nick is, there is a HUGE possibility that all of the intake valves are now bent. And if its on one side of the motor, it is definately on the other side (I will be lifting the passenger side head tonight to confirm this).
Could there be a possibility that MTI might have over milled the heads just a hair? There is less than 5K miles on this combo so its not like I wore anything out. The deck on the block has never been touched, so this is what is making me think that the heads are over milled.
I am going to be calling Jayson today at MTI to discuss this but I dont want to get into a pissing contest with him about the heads. He has been EXTREMELY helpful to me in the past and spent alot of time on the phone with me answering some pretty silly questions. I just dont want to **** anyone off and make a bad situation worse.
Any input on how I should handle this with MTI? And if it is not a clearence issue what could possibly be causing this problem?
At first I figured that it was floating an exausht valve that caused the issue. BUT since the car has a rev limiter that was programmed by MTI wouldnt that keep the valves from floating? And if it was an intake valve that was hitting then it was definatley a clearence issue. Granted, I knew prior to getting into the X1 package that the P2V was very tight in there, but everyone (MTI included) said that there was still plenty of space.
Last night was the first time I really got a chance to sit and inspect the vlaves and the piston. At first I was hoping that the mark on the piston was just a nick in carbon build up. Well, its not. It is the valve has definatly made contaact with the face of the piston. However it is a VERY slight nick. And here is the problem. It is the INTAKE VALVE, not the exauhst. which would mean a CLEARENCE issue. However slight the nick is, there is a HUGE possibility that all of the intake valves are now bent. And if its on one side of the motor, it is definately on the other side (I will be lifting the passenger side head tonight to confirm this).
Could there be a possibility that MTI might have over milled the heads just a hair? There is less than 5K miles on this combo so its not like I wore anything out. The deck on the block has never been touched, so this is what is making me think that the heads are over milled.
I am going to be calling Jayson today at MTI to discuss this but I dont want to get into a pissing contest with him about the heads. He has been EXTREMELY helpful to me in the past and spent alot of time on the phone with me answering some pretty silly questions. I just dont want to **** anyone off and make a bad situation worse.
Any input on how I should handle this with MTI? And if it is not a clearence issue what could possibly be causing this problem?
11-14-2003, 01:00 PM
#4
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Originally Posted by NataSS Inc
44 views and no replys? Ususally someone has at least said somthing funny by now.
ill say something...
THAT SUCKS
good luck man sorry about it...
what springs were you using?
11-14-2003, 02:42 PM
#7
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piston to valve clearance should ALWAYS be checked, even if you are sure that it will clear. valve seat recession, variances in cam timing, and overall lobe profile can negatively effect p-v clearance. Another thing to be concerned about at this point is the condition of the top rod bearing shell. Depending on how long and how bad the intereference was you more than likely have smashed the top shell.
Thanks
Dennis
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11-14-2003, 02:53 PM
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Originally Posted by NataSS Inc
44 views and no replys? Ususally someone has at least said somthing funny by now.
I don't know if I have anything extremely meaningful to say about this but I do have my own experience I can share that might shed some light a little on this.
Last year I wanted to run this cam and ordered it from MTI. I then was looking into heads and after talking with Jay at Absolute I decided to go with a set of his LS6 heads. He asked me how much I wanted the heads milled and I said I wanted as much compression possible with having acceptable clearance with this cam.
I told him as it sat I couldn't check the P/V clearance myself as my car was still in one piece at the time and he offered to check the clearance out himself to help me out with a 01' stock short block he had at his place (very cool of him BTW.)
So I did some of my own research and kept seeing guys such as yourself with MTI LS6 heads milled 30 thousandths and running this cam. I asked Jay if this was ok, but after he checked he insisted the most I could do was 15 thousandths. I told him about several people with the heads milled at 30 and he said "Well, if they are - I'm sure they have some valve reliefs in their pistons now." Turns out I guess he was right.
There's nothing wrong with your heads except they were milled too much is all. You can't do 30 thousandths with LS6 heads and this cam, that's all.
11-14-2003, 03:11 PM
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Ive seen this a few times, and in those few times the valves were always straight as an arrow. Dunno what else to say other than it may not be a big deal at all (although now you know, you may want to run a little smaller cam). Smooth out the tiny releifs with some sand paper, go less crazy with the cam, and put it back together. I'm sure MTI will help ya out with the cam part of things.
11-14-2003, 05:32 PM
#11
Originally Posted by Damian
Just run a thicker gasket. That will give you the clearance you need. No need in changing cams IMO. The 02 gasket is .060, thicker than the graphite. Cometic also offers thicker gaskets than that.
Josh
Josh
I'll definately get into one of the different gaskets. I just hate loosing any of the compresion. But oh well, what are you going to do. I'll just sand the new valve reliefs a bit with the shop vac going at the same time.
thanks for the input guys. sometimes I dont know what I would do with out this board.
11-14-2003, 07:08 PM
#12
Boyce, based on how you plan to use this motor I would feel very uncomfortable with minimum clearance P to V. It would be a shame to spend 30 minutes averaging 6800-7000RPM only to lose your race in the end due to an unexpected meeting of the pistions and valves again.
Since you have the opportunity to verify clearance before reassembly, I would definately use clay and verify exact P to V before bolting it back up and also verify for no bent pushrods.
Since you have the opportunity to verify clearance before reassembly, I would definately use clay and verify exact P to V before bolting it back up and also verify for no bent pushrods.
11-14-2003, 07:36 PM
#13
Originally Posted by John B
Boyce, based on how you plan to use this motor I would feel very uncomfortable with minimum clearance P to V. It would be a shame to spend 30 minutes averaging 6800-7000RPM only to lose your race in the end due to an unexpected meeting of the pistions and valves again.
Since you have the opportunity to verify clearance before reassembly, I would definately use clay and verify exact P to V before bolting it back up and also verify for no bent pushrods.
Since you have the opportunity to verify clearance before reassembly, I would definately use clay and verify exact P to V before bolting it back up and also verify for no bent pushrods.
11-14-2003, 08:26 PM
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Yah, I agree that when there is a question on if there is sufficient PV clearance, it needs to be checked. This was the biggest reason that I didn't go too crazy when I ordered my cam. I wanted something that would fit without a doubt.
11-14-2003, 08:52 PM
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If the heads are off, I would have valve reliefs cut on the intake side at least. That would be your safest bet. I think I read Lou charges like $200 or so. That isn't too bad at least. Better to fix the problem than to put a bandaide on it.
11-14-2003, 09:51 PM
#16
What is the claying procedure? Could someone thoroughly explain how this is done?
josh
11-14-2003, 10:02 PM
#17
Not to seem like a bone, but give Jayson a call and let him know your issue.
He is not going to get in any pissing match with you. Ive had all sorts of comversations with him, and never once has he not been completely honest and forthcoming with me... before totally fixing my issues.
THis si MTI we are talking about.... now is the time to be glad you didnt buy something by ARE or similar.
chris
He is not going to get in any pissing match with you. Ive had all sorts of comversations with him, and never once has he not been completely honest and forthcoming with me... before totally fixing my issues.
THis si MTI we are talking about.... now is the time to be glad you didnt buy something by ARE or similar.
chris
11-15-2003, 11:16 AM
#18
Originally Posted by Damian
Levi, put #1 at TDC. Put a small piece of clay on the top of your piston. Bolt your head down, not tight but snug with a few bolts. TQ your rockers to 22 ft lbs on that cyl. Pull the head back off. Take a micrometer and measure the indention in the clay. Thats checking PV with clay.
josh
josh
11-15-2003, 04:09 PM
#19
Visceral...lol...well said regarding ARE...IMO.
MTI always been great in my personall experience!
My heads had .020 to .030 off and we got .075 P to V with 2 degrees advance with my 224 XE-R when it was degreed in. Mine was check with a dial. Clay is better than not checking but the dial is more accurate IMO. Always a good idea to check on each specific set up because it may vary a little. Differing gaskets etc can have an impact on this too.
MTI always been great in my personall experience!
Originally Posted by NataSS Inc
Per the info from MTI the heads are milled .030 (30 thousandths)
the above cam specs are correct. The springs are what MTI provided with them at the time. I cant remember but I want to say they are comp springs.
the above cam specs are correct. The springs are what MTI provided with them at the time. I cant remember but I want to say they are comp springs.
11-15-2003, 04:22 PM
#20
Originally Posted by 99 Black Bird T/A
Visceral...lol...well said regarding ARE...IMO.
MTI always been great in my personall experience!
My heads had .020 to .030 off and we got .075 P to V with 2 degrees advance with my 224 XE-R when it was degreed in. Mine was check with a dial. Clay is better than not checking but the dial is more accurate IMO. Always a good idea to check on each specific set up because it may vary a little. Differing gaskets etc can have an impact on this too.
MTI always been great in my personall experience!
My heads had .020 to .030 off and we got .075 P to V with 2 degrees advance with my 224 XE-R when it was degreed in. Mine was check with a dial. Clay is better than not checking but the dial is more accurate IMO. Always a good idea to check on each specific set up because it may vary a little. Differing gaskets etc can have an impact on this too.
