As above and how what is best etc I am putting new pistons in a cosworth block

 

If the block is within tolerance then a hone would deglaze the bores for new rings. But check sizes and ring gaps before fitting. Mine was badly worn so I had no choice but to reborn to a larger size.

 

Wellit has 50k on the clock and I can see what I can discribe as the hone marking on the bores still and whats te best way to check size?

 

You need a bore gauge to check sizes but any engine machining place will check it and advise if it will hone within standard sizes. Mine had a step at the top and was badly worn, so I had no choice but to go +0.5mm

 

Ok thanks for the info guys I really hope it's within size as I have my std size pistons and I did try one in tr bore with no rings it I would say that it wasn't a lost fit still make kinda a suction as I tyres removing it

 

Take your pistons and block to your choice of engine machining service, they will mic pistons and measure bore. That will then confirm if block is ok on current bore. If not then unfortunately you will require new pistons. If your pistons are used then check grooves for rings as well as these can wear. My engine was at less than 60k miles and was badly worn, common I believe on 2wd with central gudgeon pin pistons

 

It is originally a pinto if that makes any difference I have a digital veriour gauge what's the size ment to me a max of , I know there 90.8mm std I think I will mesure now and let you know

 

Measuring at the top is no good, you need a bore gauge and measure it down in the bore. Also you may find the bores have 'oval'd. ie they maybe ok measuring in-line with the crank, but measure across-90degrees to the crank- and they maybe out of tollerence