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Ring sizes

Started by Pahs59, August 09, 2021, 09:50:19 AM

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Pahs59

I have a set of     3. 1/16 STD rings
What size pistons are these for
They came with the car and was told there for the motor that was in it and it’s a B motor
Putting the ring into the cylinder to check the gap and the gap looks way to big at least 5mm
Pistons have 7406474 stamped on top
Thanks

ardiesse

Three-and-a-sixteenth-inch is standard bore size for all B and J motors.

If, when you put one of these rings into the bore, and the ring gap's at least 5 mm, that means that the block's been rebored.  (5mm/pi = 1.6 mm = 1/16")  I'm guessing that the block's been rebored to 3-1/8".

Or, the rings are for a 3" bore (132) motor.

Do you have a digital caliper?  Measure the bore diameter.  That'll tell you.

Rob
Remember: if your Holden's not leaking oil, it doesn't have any.

ardiesse

7406476 is the part number for standard-bore 3-1/16" pistons.  Normally the part number goes up with oversize.
7406474 has got me beat.

Rob
Remember: if your Holden's not leaking oil, it doesn't have any.

grey nomad

.040” oversize.  AL.