Piston replacement

This is the damaged piston. Hoping to locate a single piston.

Given the C# stamped on the top, this is an original jag piston. Searching the catalogues of suppliers will return this part number but it will probably be an aftermarket substitution. I would phone all of them and ask if they have a NOS single original one sitting on the shelf. Make sure they know you need a new factory one to replace a damaged one. Don’t forget Terry’s and Welsh, and maybe some of the less known here European engine builders.

You can also do a search on Ebay and save it so you get email updates as soon as one appears. Just make sure it’s a factory part. This may not be an instant gratification search but I guarantee someone has one sitting on the shelf somewhere. You might want to join the forum across the pond and put out the same feeler.

In the worst case you can probably substitute a good condition used one but it’s less than ideal.

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Than you Erica.

I have emails out to a few you listed with pictures. My contact with them previously confirmed they might have a single replacement piston, but at that point did not have the pictures to confirm the information I now have. Fingers crossed.

The EBay search is super helpful. Have done that in the past both in finding and selling. :+1:

Well pistons? I have a lot from all of the engine’s.


Wow Frank,
I am impressed with all the various parts you have. I bet many of them would help many people.

Nicole, if you find a good used piston somewhere , you can have it tested by a machine shop for hidden fractures etc. you have all the serial numbers. Used pistons have been tested by actual use, lol.

I think you would be fine using a used piston. Which was especially made for the original engine. Are the other pistons original too?

Good luck


Before reusing a used piston you’d be best advised to mic the ring grooves to confirm spec.

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Yes, a point I made to Candie: used is fine, if all the specs are in spec.

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In the second photo, on the bottom right, you can see something stamped on the piston. It could be the letter used by Jaguar to indicate the piston grade (weight/ dimension).
Good info if trying to source an old OEM piston

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I think this was a G grade - check - so a G piston from a running engine and reasonable wear (skirts and ring grooves) would fit perfectly, the gudgeon pin is matched, new clips to hold it in of course.

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Yes, all original.

Any chance you have a match to what I am ISO?


Try this guy has a lot of nos stuff
eBay seller


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Also Siestasun. He had many engine and gearbox parts.

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I have a couple of sets sitting around and will see if the numbers match. Just pay shipping and they are yours.

Just checked and they are different.

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Well, I checked the 4.2 Liter piston, but there are no matching number, only R15 of the top of the piston. They are all STD, standard pistons, from 3.4, 3.8 and 4.2, a set.
Can you try to weld your piston?

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Thank you for checking.

Probably not going to weld. Would rather find replacement. (Fingers crossed).

Not anything you want do to a piston crown.

I’m asking myself whether it makes more sense to install a new modern and matched set rather than replace a single mismatched piston. The head and sump are off so the hard part’s done. A set of Mahles will be around $600, $100-ish for big end bearings if you’re inclined to replace them, rod bolts and nuts reusable unless they’re ARPs. You could even do a rehone with the crank in situ if you’re careful to distance and protect the rod journals.

Or, am I out to lunch, experienced engine rebuilders?

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That might end up being the easiest way to do it: that said, there’s no problem installing a single piston if it is matched in weight and dimension.

Candie’s engine is zero mileage, on newly-honed bores, so that’s unneeded.

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Would that mean removing a second piston to scale it and compare it to the replacement? And if the replacement is significantly lighter then what does one do to correct it?