Piston Htting heads
#12
04-20-2008, 05:15 PM
RE: Piston Htting heads
I just love oxymorons. You gave us another example of one.
ORIGINAL: ZD
Engines usually have a tolerance called "Deck Height", which is measured with a depth michrometer from the top of the cylinder wall to the top of the piston at TDC.Some engines require a 'standard' to use as a base if the piston is designed to come out of the bore at TDC.
Should be a no-brainer for the dealer unless they don't do overhauls. If the deck height is wrong, then either the base is machined wrong or the pistons need to be machined for proper clearance and rebalanced.
I'm no expert on Harley engines by any stretch of the imagination, but I have built engines of all sorts, from motorcycles to autos to aircraft over nearly 40 years... I can't imagine that the clearances are so close that this could happen without something being pretty obvious to to the trained HD engine technician.
Engines usually have a tolerance called "Deck Height", which is measured with a depth michrometer from the top of the cylinder wall to the top of the piston at TDC.Some engines require a 'standard' to use as a base if the piston is designed to come out of the bore at TDC.
Should be a no-brainer for the dealer unless they don't do overhauls. If the deck height is wrong, then either the base is machined wrong or the pistons need to be machined for proper clearance and rebalanced.
I'm no expert on Harley engines by any stretch of the imagination, but I have built engines of all sorts, from motorcycles to autos to aircraft over nearly 40 years... I can't imagine that the clearances are so close that this could happen without something being pretty obvious to to the trained HD engine technician.
#13
04-20-2008, 09:16 PM
RE: Piston Htting heads
You need to check the squish on this while you have it down. This will tell you what the clearance is. There should be about .034 in your engine for best burn and least ping. I would be wondering if it is the gear drive making the noise. One other thing, if the pistons were changed were they forged or cast? The forged will be louder.
#15
04-20-2008, 11:23 PM
Extreme HDF Member
RE: Piston Htting heads
What cam are you using; and with what heads? If you used valve springs with insufficient seat pressure with a high lift cam you may be floating a valve--i.e. the valve spring isn't strong enough toclose the valve allowing it to "float",and contact the piston.
Also, were the heads machined at all? Really, there are a bunch of explanations, but without details of the build, machining (if any), and the assembly you'll just be stumbling around in the dark.
Also, were the heads machined at all? Really, there are a bunch of explanations, but without details of the build, machining (if any), and the assembly you'll just be stumbling around in the dark.
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