Ckecking PTV clearance with clay
08-19-2010, 11:52 AM
#1
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Ckecking PTV clearance with clay What clay are you using? Just something from the arts and craft store? or something more specific? Thanks
08-19-2010, 02:16 PM
#3
Werd, modeling clay is where its at. Do you already have the engine apart? Or are the heads bolted up and you have no reason to remove them, other than checking PTV via the clay method?
08-19-2010, 06:57 PM
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08-20-2010, 07:48 AM
#8
Actually, it is very accurate if you use the proper procedure and you don't even have to remove the heads. This is what I was going to recommend, BUT you already had your heads and everything else off. You actually start @ 15 degrees BTDC and measure the allowable clearance between the piston and valve as it drops. Start off with broad range, like rotate engine and check every 5 degrees, and then dial it in from there until you find the maximum. This is with a dial indicator above the valve with checker springs.
08-20-2010, 09:11 AM
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Actually, it is very accurate if you use the proper procedure and you don't even have to remove the heads. This is what I was going to recommend, BUT you already had your heads and everything else off. You actually start @ 15 degrees BTDC and measure the allowable clearance between the piston and valve as it drops. Start off with broad range, like rotate engine and check every 5 degrees, and then dial it in from there until you find the maximum. This is with a dial indicator above the valve with checker springs.
08-20-2010, 12:18 PM
#10
I did it every 2 degrees starting at 20 before through 20 after TDC on the exhaust stroke. This is much more accurate. Clay can get distorted and provides inaccurate measurements. It is good as a confirmation of measured values. The only thing that isn't taken into account when you use dial indicator is flex of the valve train so it will be a bit conservative which is what you want.
08-21-2010, 03:20 PM
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I did it every 2 degrees starting at 20 before through 20 after TDC on the exhaust stroke. This is much more accurate. Clay can get distorted and provides inaccurate measurements. It is good as a confirmation of measured values. The only thing that isn't taken into account when you use dial indicator is flex of the valve train so it will be a bit conservative which is what you want.
