hey ive been looking around to try and find oversize valves for 4k all i can find so far is that gemini apparently can be put in and some type of laser anyone here know any bigger valves to fit 4k head and what springs are you guys using with bigger cams?

take it to a machinist! you will need new seats to suit the bigger valves and possibly bigger/smaller valve guides to suit.

 

how about valve retainers/springs?

 

will the head be ported?

 

crow cam double valve springs p/n 4220 $90 a set. .500" max lift before they bind

Edited October 14, 201115 yr by Evan G

its 7k mani s/c and ported like all F talking to my machinest today said maybe we can go a little bit bigger and use stock seats and thanks for letting me know about the crow stuff.

does anyone do titanium retainers?

crow cam double valve springs p/n 4220 $90 a set. .500" max lift before they bind

I don't believe they have enough seat or nose pressure for a big boost/big cam application.

My old setup required 90-100lb at installed height and 240ish lb at nose of cam.

 

Stu.

what springs did you use kickn5k?

theres another valve spring they make i think its the 3880. single with a helper strip with max lift of .480

ill choose a cam then get springs to suit with around 50thou before bind on max lift

what springs did you use kickn5k?

I used the crow 60lb at installed height springs. Even though they are not what the cam guy wanted me to use they were closer than the 40lb STD spring. I also had them.

 

Stu.

i use some sort of commadore spring? think its maybe vn.. not sure

holden 202 springs will fit vn or any 3.8L commo will NOT fit. i have pics to prove this

holden 202 springs will fit vn or any 3.8L commo will NOT fit. i have pics to prove this

Don't forget Evan Holden did make a 5ltr V8. I'll have to check over some measurements. They were the closest I could find to fit from memory. They are a bit bigger in diameter and 3/4mm taller in installed height. But that's an easy fix if you've got the head at machine shop getting bigger valves fitted.

Mitch what boost is your thing running again? You'll need to factor that into your spring pressure choice.

 

Stu.

12psi :) now tuned on E85 with 130hp not bad for stock cam

nason engine parts had a special a while ago on some OS valves... i bought a set for like 20 bucks. i can't remember part numbers but i think they were gemini ones???

 

if you can find a parts store that deals with nason (repco, autopro etc) they should be able to call them and get the info. upon a quick search part no's could have been GEMEX2144 and GEMIN2143, probs best not to quote me on that though