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I'm here to cause trouble
Join Date: Mar 2005
Location: CA
Posts: 935
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Can REAL TDC be where the TDC tool indicates?
We're using the Stomski TDC tool to locate true TDC during an engine rebuild (cam timing tomorrow) ... never used one before. Is it normal for the TDC that the tool indicates to be about 1/32" to one side of the Z1 pulley groove? Just need a sanity check... Thx!
JB |
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04-16-2009, 03:47 PM
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Navin Johnson
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 8,808
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Yes.
Quote:
Finding TDC using a tool/dial gauge/screwdriver etc. lets you find exact TDC... It also allows you to find out how far off the marks on the pulleys flywheel are..
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Don't feed the trolls. Don't quote the trolls  http://www.southshoreperformanceny.com '69 911 GT-5 '75 914 GT-3 and others |
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04-16-2009, 04:40 PM
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The most accurate is the dial indicator with degree wheel method @.050-
or that seems to be the most accruate to me
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Kris @ Tech9 86' 930/GT-40R Sold  94' Rustang GT daily (long gone) 2008 C6/Z51 Corvette |
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04-16-2009, 09:28 PM
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Registered
Join Date: Feb 2006
Location: Oahu
Posts: 2,303
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Anyone else using one of these to assist?
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Jon |
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04-17-2009, 02:58 PM
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Registered
Join Date: Jul 2000
Location: So. Calif.
Posts: 19,910
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I haven't seen the Stomski TDC gauge, but the most accurate method uses a mechanical stop. Dial indicators, whistle indicators and screwdrivers inserted into the spark plug hole are only approximate. Near TDC, there's relativetly little piston movement compared to the rotation of the crank, and it is the crank that should be the reference.
Think of a tool that looks like a hollowed out spark plug and threaded internally with a long bolt and lock nut. The best time to find TDC is w/o the timing chains installed. In fact, a mechanical stop can be fashioned without the cylinder head installed. Position no. 1 piston toward TDC. Insert the stop bolt assy., then thread the bolt inward until it contacts the piston. Carefully reverse rotation of the crank, then again rotate the crank slowly until the piston contacts the stop. Place a temporary mark on the pulley. Carefully rotate the crank in the opposite direction about 360º until the piston again contacts the stop. Mark the crank. There are now two marks on the crank. The distance halfway between the two is exact TDC. If the mark is different from the existing factory mark, file a V-shaped groove to indicate true TDC and apply some white paint on it to make it more visible. Establishing true TDC is essential to arrive at the specified cam/valve timing. Sherwood Last edited by 911pcars; 04-17-2009 at 11:24 PM.. |
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04-17-2009, 11:20 PM
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2002 Porsche 996TT
