hi peeps , i am just wondering if any of you can help me with the any of the following combination of pistons all to be standard items , anny help would be very helpfull
standard 2wd cosworth
205 block -4x4 pistons-2wd head
the cc of a 2wd head
the cc of a 4x4 head

thanks gary

 

cubic capacity of a standard YB (all flavours) is 1993cc.

The 4x4 pistons are a direct replacement for the 2wd ones, and shouldn't make a difference to the cubic capacity.

Standard compression ratio is 8.0:1.

 

thnks for the reply cozmeister, i should of made the question clearer

i am looking for the compresion ratio of a 205 block with 4x4 pistons and a 2wd head and a group a gasket , im prty sure the 4x4 pistons have a bigger dish so should lower the compresion ration when used with a 2wd head ,

as for the head question i meant the cc of the combustion chamber in the head ,
thanks gary

 

it would in theory drop the comp to 7.8:1

 

100% correct (given that the head is not machined to fuck ).

 

thanks silky and mike for comfiming it , the head that went on was measured at 138.6 ,and was a group a gasket used ,im not sure if these are the same compressed thickness as the orignal one ,
can any one help with the cc of the heads

thanks again

 

a 2wd head i measured recently was 53cc and irrc it was 138.9mm thick.

 

lovely ,thank you very much

 

dont know if it helps but i reckon old valves (with low margin) will add another 4 - 5 cc and polished chamber prob another 1 or 2

 

didnt think of that , think i will measure it me self so i no for sure , thanks