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Join Date: Mar 2003
Posts: 231
clearance

Hi guys,i'm building a 2.7 with E-cams flat pistons (RS 8.5-1) 0.75mm base gaskets 1mm deck height,1.3mm piston to head clearance.I timed the cams to spec. 3.25mm (0.125 in.) The piston to valve test yields the rocker adj.screw goes all the way in (~ 6 turns) without hitting piston in many places on both sides of TDC.Why the great distance ?Thanks T.C.

Old 03-27-2012, 11:45 AM
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Join Date: Oct 2003
Location: Central Fla
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clear.

Are you checking it either side of TDC at overlap or on compression ? It needs to be at overlap cams timed, usually I start with the intake at 10 deg. ATDC and the exhaust at 7 deg BTDC, and use zero lash and turn the rocker adjuster in carefully.

Mike Bruns
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Old 03-27-2012, 12:23 PM
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clearance

I'm at overlap TDC.Dots on cams are up Z1 lined up with case parting line #1 rocker can be rocked slightly.From this set-up and your own experience what do you think the clearance should be approximately?
Old 03-27-2012, 01:02 PM
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clear.

Too many variables, those pistons were run with "S" cams but all things were new, "E" cams should have plenty of room but you must check it, the rule of thumb for valve to piston on the intake is 1 mm and exhaust 2mm plus at min. the important thing is that it is checked at the closest position (and that is not at TDC) start with the positions in the above post to begin with, the thread pitch on the adjusters is 1mm per turn.
Mike Bruns

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The two most useless things to a driver are the braking distance behind you and nine-tenths of a second ago.
Old 03-27-2012, 01:26 PM
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