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Location:
qld
Registered:
May 2003
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fly cutting pistons
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Sat, 10 January 2004 10:51
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hey im am planning to build up a 3tg hybrid and i need to fly cut the psitons just wondering has anyone done this and if they have, how much is needed to be cut out.
as my engine rebuilders said we will have to measure it all up and do a dummy assembly, so it would save alot of time if i already had the information.
jason
thanks alot
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Location:
Brisbane
Registered:
June 2003
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Re: fly cutting pistons
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Sun, 11 January 2004 05:26
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take your head, valves and block to a qualified machine shop/ engine builders. dont do it yourself, its almost impossible to get it right
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Location:
Perth
Registered:
September 2003
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Re: fly cutting pistons
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Mon, 12 January 2004 06:00
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definitely a job for the pros.
the max you'll want to flycut is 1.00mm, any more and you're really asking for trouble.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: fly cutting pistons
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Mon, 12 January 2004 06:13
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dummy assembly is the most accurate way since not ever motor is alike. and piston-valve clearnce is particularly difficult, as cam lift, duration and ramp-rate (as well as head thickness, valve seat recession, etc etc) will affect the final numbers.
it involves putting head on with 1 set of valves (for one cylinder, measuring valve lift with dial indicator, and measuring crank angle at contact.
can also use plasticine on the top of the piston (maybe covered with gladwrap to stop it sticking to valve) rotate engine, same thign again.
you can use a used HG for initial measurements, but if you are getting the lumps machined, i'd recommend to use a new HG, torqued as will be done in final assembly, for every dummy fit.
dummy fit and measure as described above. double check all measurements. get pistons fly-cut professionally. dummy assemble again using 2mm thick plasticine. check that you have at least 1mm???? clearance between vlave and piston at all times (use a razor blade to slice thru the valve indent in the plasticine to see the clearance to the piston)
good luck.
at least you get lots of practice assembling the motor 
Cya, Stewart
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Location:
qld
Registered:
May 2003
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Re: fly cutting pistons
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Thu, 15 January 2004 05:32
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when i look at my 2tg pistons there are fly cut standard, right and there has been a massive chunk removed from them. not exactly sure how much maby 5mm or more just wondering if ill be able to cut enought out.
jason
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