2 replies to this topic

[ntvrman]

Hi,

hoping someone can help. I’ve had the block rebore to 70.88 which I am told is only 1000th .

so with that I am looking to reuse my 21268 pistons. What ring set should I use.

the full stamping on the pistons is 21268 GB L05 here’s hoping you can help.

Also I do have a different set of pistons 20142 H11 +.020

thanks for reading.

ntvrman

[timmy850]

Sounds like great questions you should be asking your machine shop. All the running clearances should be checked and measured and within spec

 

Use pistons are often a false economy

[Spider]

The nominal stock Bore size for a 1275 is 2.78" or 70.612 mm

 

At 70.88 mm that's 2.7905". That's 0.009" over the nominal Stock Bore size. While you need to measure the pistons you have to calculate the Piston to Bore Clearance, these can be around -0.000 and + 0.001", I'd almost certainly say you'd be up for a re-bore to +0.020"