Just rebuilt my 3.0L and went to 98mm pistons. Pistons just touch cylinder heads????
05-15-2006, 08:32 PM
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Just rebuilt my 3.0L and went to 98mm pistons. Pistons just touch cylinder heads????
Just had my engine rebuilt and "upgraded" from 95mm to 98mm p&cs .
Started it up and had a knocking sound. Took it back to the engine builder ( A very well known and reputable guy.) he discovered that the piston dome just touches the cylinder head. He chamferd the head and says no problem.
Has there been any other feed back about this happeninng with this switch?
Thanks
Started it up and had a knocking sound. Took it back to the engine builder ( A very well known and reputable guy.) he discovered that the piston dome just touches the cylinder head. He chamferd the head and says no problem.
Has there been any other feed back about this happeninng with this switch?
Thanks
05-15-2006, 10:35 PM
#2
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Each & every engine builder MUST perform due diligence and check (and adjust) deck height on every motor. This applies to DIY'ers as well as professionals.
Sounds like somebody dropped the ball and didn't do that,...............
Sounds like somebody dropped the ball and didn't do that,...............
05-15-2006, 11:03 PM
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Thanks Steve.
Does it make sense that only one cylinder did this and would that indicate other problems? Also, If it is only one cylinder, is chamfering the head enough? Would this cause a difference in compression between the other cylinders? Is that a problem?? As I said before, the shop that built this is a well known Porsche engine builder so I was a little surprised by this occurance. He was very helpful in the whole process and even came over to the house to help diagnose the problem.
Thanks again.
Does it make sense that only one cylinder did this and would that indicate other problems? Also, If it is only one cylinder, is chamfering the head enough? Would this cause a difference in compression between the other cylinders? Is that a problem?? As I said before, the shop that built this is a well known Porsche engine builder so I was a little surprised by this occurance. He was very helpful in the whole process and even came over to the house to help diagnose the problem.
Thanks again.
05-16-2006, 12:06 AM
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Well, it actually should be pretty fun. Even with the "knock" it sounded great! (even if it was for a few seconds.)
"PORSCHE, There is no substitute!!" and "That noise will go away." Two great quotes.
"PORSCHE, There is no substitute!!" and "That noise will go away." Two great quotes.
05-16-2006, 04:11 AM
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LOL,..Wellsir, it sounds like somebody didn't check deck heights,... If they are not the same in each cylinder, you can have piston-to-head contact (as you did) and different compression ratios in each hole.
That makes for an engine with different detonation thresholds in each cylinder. In some cases, the cams bind up and do not turn easily when the heads are torqued up.
If they are not the same in each cylinder, you can have piston-to-head contact (as you did) and different compression ratios in each hole.That makes for an engine with different detonation thresholds in each cylinder. In some cases, the cams bind up and do not turn easily when the heads are torqued up.
