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 30 2007, 10:03 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 |
Bzzt. I'm wrong again.
Now I think that the heads are fine... I swapped the heads (put 3&4 bank on the 1&2 side, and vice versa) and re-did the leak down. So the #1 cylinder head was now on the #4 cylinder, and the #4 cylinder head was now on the #1 cylinder. I re-did leak down on Cylinder 1&2&4. I skipped doing leakdown on three. Cylinder 1 (Head 4) still leaked at 55%. Cylinder 2 (head 3) was cool at 7% Cylinder 4 (head 1 - which I thought was the leaky one) was also cool at 7% I measured the #1 cylinder from behind the shim to the mating lip, but was not able to get a measurement I was able to replicate from time to time. But I now either need to go back to either that the cylinder needs shimmed up about .005 inches, or the case needs decked. *edit* actually, I need to get the cylinder measured by someone who can replicate the measurement. Mine seemed to vary too much for me to put any stock in it. */edit* I had negated my previous theory as Josh had suggested that they way I went about it was inaccurate. But, I am going to try my spacer before I deck the case. Now I just need to find a .005 inch cylinder spacer. I also talked to Evan yesterday, and checked out a lead he had remembered, but it, much like communism, was a red herring. Would have been sweet if it worked though. Zach |
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