there is no direct fit oversize valves for the 4e head. This job always need a fair bit of machine work.
I have use supra valves 1mm oversized and other custom made 1,5 mm oversized.
If you thinking going this route ask for a 3,5, multi angle job and full port and polish job.It is also other jobs that can be done to the head to improove its performance.
Before attemting anything make sure it is a healty head you will use as a base.
Cruise springs can be found here at the traders section.
If you need any guide for a diy job or any other details pm me and i will try my best.
Have a look here to get an idea..It was at early stages but you can see what is envolved.
http://s723.photobucket.com/albums/ww231/350ep70gr/starletgtturbo1 head/
Chris
ya i know my head will have to be machined..the vavle seats will need to be chamferred to suit the valve size..ya if i am goin this route ill be also using 5efhe cams and the cruise springs.... it should make a good difference..
did you notice much difference in your head? did you use standard springs, cams? also how much did it cost for you..pm me the price if you want..
It made a fair bit of a difference even on the little ct9 back to the days.
Cost me very low as i did all the machine job myshelf and only buy valves and springs.
Chris
thay will make allways some gain but no one can tell you when and by how much. it depends in many thinks engine setups ,boost type of head ports. but you will have gain and better head flow 110%.
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but can i ask why people want all that hassle?when the standard bits work fine,like what sorta power are people looking for?when people have made 400+ on stanard valves with no problems