head question

[kinter86]

I seen on 2gnt that you can swap 4g63 valve spring into the 420a. So, i was wondering if I upgrade the springs to the 4g63, 2.7l pt crusier lifters and rocker, and ss standard size valves, new seal, how much hp or boost do you think it could handle.

 

[Locke]

The same as before. 2.7 rockers have updated oiling as do PT lifters, 4g63 springs have a higher spring rate, and SS valves won't make anymore power than inconel or any other valve material.

 

[kinter86]

alright, thanks.

 

[kinter86]

do you think it would o.k. to rev over 7k?

 

[Locke]

I believe Bullett was revving over 7k with a larger camshaft and factory springs. Shouldn't be a problem at all with 4g63 springs and factory cams, within reason.

 

[NeMiZiS]

Doesn't the 420A power ban end at 7000 RPM's?

 

[Locke]

Probably closer to ~6800.

That is a good point, though, Nemezis. With a factory head (cams, valve size, porting) and being naturally aspirated, there isn't really any benefit in spinning the engine faster than it is already able to.

 

[all_motor_mike]

edit after seeing post above.


mike

 

[kinter86]

o.k. so ill check out some larger cams, thanks for the input guys.