I realise this is probably very cheeky trying to get techinical spec from jaguar owners when trying to rebuilt a Bentley Mk6 engine but I'll expain why.

I need to know the standard bore size on a jaguar 4.2. I need to know if it is exactly 3.5", the Bentley is 3.5005" and my pistons are 25thou oversize, so I'm guessing a set of +30 thou rings will do if the bore is exactly 3.5"

Bentley piston rings are a fortune at over £200 a set and I cannot get the size i need , and jag ones are approx £50.

Can anyone help?