Piston Markings

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Page created by T July 6th 2014:

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0.060" Oversize marking on a 253 Piston. 0.0015" is the clearance to be measured between the bore and the BOTTOM of the Piston. The notch must be positioned as per the manufacturer's requirements. Holdens use offset gudgeon pins to reduce piston slap. Fitting the piston with the notch to the wrong side will jam things up. Photo by 2HQueues. Click to Enlargen.


==Piston Markings:==

===Piston Markings Explained:===Typical Piston Markings show the oversize of the Piston, the clearance that must exist between the cylinder and the Piston and where that clearance must be measured.

====Piston Oversizes:====These might be








This is a 0.060" oversize 202 piston, piston to bore clearance of 0.002 measured at the RIB of the piston skirt. RA9118A is the ACL race series part number. Photo by TUFFVB. Click to Enlargen.


This is a 0.060" oversize 308 piston, piston to bore clearance of 0.0025 measured at the TOP of the piston skirt. RA2501 is the part number. AG is the batch number. Photo by TUFFVB. Click to Enlargen.


By v8slrtorana 16/06/07@18:46 Shed LetsCruise 0830

It does not come up in the latest ACL catalog
TOP 0.0025 = Position of skirt to measure clearance
AC/AG is batch number.
060 is 0.060" over bore.
RA2501 is piston part number.

End of submission by v8slrtorana

====Piston To Cylinder Clearances:====The Photo shows a clearance of 0.0015"

ACL RA2027 Piston for a 186 Holden Engine. 0.060" Oversize Piston with 0.0015" Clearance between the TOP of the Piston Skirt and the Cylinder. Photo by Blissy. Click to Enlargen.

====Piston To Cylinder Clearance Measuring Point:====

TOP - The TOP of the Piston skirt. 

CENTRE - The CENTRE of the Piston skirt.

BOTTOM - The BOTTOM of the Piston skirt.

RIB - Centre of the piston skirt.




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