Fixing poor leakdown, Cyl 1 leaks at 50%, rest are cool. |
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Fixing poor leakdown, Cyl 1 leaks at 50%, rest are cool. |
VaccaRabite |
Oct 24 2007, 07:00 AM
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#1
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En Garde! Group: Admin Posts: 13,475 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
So, at the Sterling meet I did a leakdown test on my motor, and found a problem with Cylinder 1. 45% leakdown, but 120 lbs of compression. Was tempted just to let sleeping dogs lie, but pulled the head off.
What was going on was clear as soon as we did that, the head was not totaly sealed to the cylinder, off by a very small amount. Instead of having the head recut, I decided to try and lap the two of them together. So, last night I hand lapped them, using ground graphite to check for even contact. I got good contact after the third round of hand lapping (lap, clean, check). Now I need to get the jug back on the block. I have a ring compressor on the piston, but I can't ficgure out how to get the head back on. Do I have to take the piston head off the rod? If so, how do I get it off. It looks like that tis a spring keeper that needs to be removed. Is there anyhting on the rod the needs to be loosened before I can pull the pin out to remove the piston head? Obviously, if there is a trick to getting the jug back on without pulling off the piston head, I'd like to do that. Zach |
VaccaRabite |
Dec 31 2007, 06:58 PM
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#2
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En Garde! Group: Admin Posts: 13,475 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
My rings are golden. As on good, not gold colored. :-)
' Are the Chinese Cylinders... Dunno, let me go see if they say anything. Not Chinese. Cyl #1 is stamped: "039 101 ?01C 18 15 17 VW" The "?" is either a 3, 8 or 9, I can't tell. Pistons are Keith Blacks So, today I tried the 1000grit sandpaper on glass. There were two very shallow depressions where the ink stayed, but neither of them were where the leak was. However, I polished the cylinder until it was level, and put the head back down. 70% leak, worse not better. But that made sence as I had just removed a little metal. I measured the cylinder and got 6.008 inches. I measured several times, and was able to replicate the measurement at different points. Good, I think I have it level now. I pulled the #2 cylinder off, and measured it. I noticed right off that it had 2 spacers to the #1 cylinders single spacer. I measured it at 6.020 inches. One of the spacers was .010 inches, so I removed it and remeasured. As expected, the cylinder (#2) was now at 6.010 inches. I was going to put it all back on the block and re-leak it, but my wife let me know that I should consider heading in for dinner. We had cancelled our NYE plans for the evening, so after dinner I'll head back out and put everything back together. I guess I am going to need to re-measure deck height since I polished one cylinder, and took a base shim off another. Or, I suppose I could buy a .010 shim to bring the shorter cylinder up, which is what I probably need to do. Right now I think that I should be within .002 inches of one to the other, which should even out the leak down, right? Jake, would you like me to continue posting this on your forums too? Zach |
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