Piston size

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admin_maintenance
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Piston size

Post by admin_maintenance »

This is the top of my piston. I am reading this right that it is 10 thou???Image
Blacky
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Re: Piston size

Post by Blacky »

.001 would be one thou ????
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EK283
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Re: Piston size

Post by EK283 »

Hard to tell,

You would need to measure it with a set of vernier calipers.

Greg
Last edited by EK283 on Tue Jul 06, 2021 8:43 pm, edited 1 time in total.
So many cars so little time!
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Harv
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Re: Piston size

Post by Harv »

Agree - vernier it.

The originals were stocked as standard, 1-thou oversized, 2-thou, 3-thou, 20-thou, 30-thou and 40-thou.

Cheers,
Harv
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admin_maintenance
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Re: Piston size

Post by admin_maintenance »

Ok thanks. This is the original engine out of my FJ. Just wondering if I should get it rebored or re-ring it.

Ive had the car 35 years and I have never rebored the motor so I would not be surprised if it is only 1thou

Thoughts
Jason
ardiesse
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Re: Piston size

Post by ardiesse »

Jason,

The .001 here is the specified clearance between piston skirt and bore.

The oversize (if any) will be on the next couple of lines of text. I can just make out STD below. These are Repco (ACL) pistons, so the motor's already been rebored. My guess is that the pistons will be 3.0625", with an outside chance of 3.125". Measure across the bottom of the piston skirt.

Rob
admin_maintenance
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Re: Piston size

Post by admin_maintenance »

Image

I think it read 3 or 2 075 STD If that makes more sense
admin_maintenance
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Re: Piston size

Post by admin_maintenance »

Image

A quick measure with some calipers??
ardiesse
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Re: Piston size

Post by ardiesse »

3" + two small divisions + about half a small division (vernier scale is affected by camera parallax), which is
3.000 + 0.050 + 0.0125 = 3.0625". This is standard bore size for a 138 grey.

The Repco part number for the pistons is RA2075.

How good are your gudgeon pins? Can you rock the big end back and forth (not side-to-side) at all? If there's any perceptible play, it's best to get new piston pins (Nornda aka JP in Adelaide), new small-end bushes, and have the bushes replaced and reamed to size.

Rob
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