m20 vale sizes ?

[exup]

Going to do an ETA con version using a 320i 731 head, read that its better to put in 325 valves into that head from an 885 head, whats the std valves sizes for a 320 and 325 ?
and whats the biggest valves past std you ca ftt into a 320 head, ???, , and will any 325 cam do or has it got to be post 88 ??

[cabrio327i]

Hi, You cant just put 325 vavles into a 731 casting, the seats have got to be machined out to fit the larger valves which are 2mm biger than the 320 ones in the 731, its a lot of work involved, I have one allready done just needs the valve seats lapping in and a skim want Ԛ£150 for it, cheers Dave

[exup]

Thanks 4 the info
, i have acces to a 6ft pillar drill , so assume i could find a drill big enought to open up the existing seats to the 325 size, then open up/ blend the ports to suit ?, how do u do yours ?, are 325 v/v es the biggest that will fit ? , cause if i buy new v/v s i might as well get the biggest i can ?
cheers

[Andy335Touring]

You need a special tool to cut the valve seats for bigger valves, not a DIY job !