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VaccaRabite |
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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 |
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VaccaRabite |
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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 ![]() |
I pulled the heads, and then made some spacers out of some 1 inch square tube steel stock i had laying around, and used them to re-tighten the cylinders down. I did not tighten them to spec, as I was concerned about breaking a cooling fin, but I got them to where the cylinders could not move.
I put a level with a good straight edge across the cylinder bank and looked for gap. If the level was square on the #2 cylinder, then there was a bit of gap on the #1 cylinder. This was somewhat expected, all things considering. Using feeler gauges, I measured the gap. Where the bubbles were forming (#1 cylinder, facing the #2 cylinder) there was a .007 inch gap. On the opposite edge (facing the flywheel) was a .005 inch gap. In my leakdown-bubble tests, in the spot with the .005 gap showed no leak (no bubbles). I don't think I can manipulate my calipers accurately enough to measure the lip of the inside of the #1 cylinder. It seems pretty clear to me that the cylinder is either sitting slightly cocked, or is not squared off at the top. I'll have to measure that tomorrow. Zach |
davep |
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#3
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914 Historian ![]() ![]() ![]() ![]() ![]() Group: Benefactors Posts: 5,162 Joined: 13-October 03 From: Burford, ON, N0E 1A0 Member No.: 1,244 Region Association: Canada ![]() ![]() |
I put a level with a good straight edge across the cylinder bank and looked for gap. If the level was square on the #2 cylinder, then there was a bit of gap on the #1 cylinder. from this statement I'd say that either cylinder 2 is too tall or cylinder 1 is too short. If the gap is not even from one side to the other of cylinder 1, then one of the two is not sitting square (register droop) or the cylinders have unequal heights, not square, or some combination. I'd pull each cylinder, place on a flat (like glass) and use a height guage to ensure (a) equal height while spinning the cylinder, and ((IMG:style_emoticons/default/cool.gif) equal height for each cylinder. Since the bottom seating surface is not the bottom of the cylinder, you have to invert the cylinder on the glass and measure the height of (a) & ((IMG:style_emoticons/default/cool.gif) to the seating surface. If there is any variation, then do as Jake suggests. If there is no variation, then suspect a drooped case register or two. |
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