What Valves To Upgrade To On 4K Head After Port Job?

[Mezz///]

Hello guys and Girls :)

 

Ok so I bought a ke26 a year ago with a mild 4k.

 

I was told it had a 3 angle valve job on it..

The exhaust valves in the 4k head have a little S stamped on them.

 

Questions:

 

1.)Are these special valves?

 

2.)What does the S mean?

 

3.)I am wondering what valves to use on inlet and exhaust if I have done a MAYJOR port and polish of both the intake and Exhaust ?

 

4.)has anyone done a port job on a 4k head and brought it out to 35mm on the inlet ports,And just match exhaust ports? how was this set up for you and what should I expect when I put the head back on the block and start it? have I gone too big? Or will this flow really well if I put bigger valves in?

(These ports have been match ported with intake manifold and extractors)

 

Thanks guys,lots of questions here I know.. May need some experienced people here to answer.. Hope I have made the questions clear as glass?

 

Mezz///

[Mezz///]

I think the guy that told me the valve work that was done,..was pulling my leg??!! It didn't look any different to standard exhaust valves btw

[Mezz///]

35mm round ports on inlet by the way ;)

[philbey]

Measure the valve diameter. I suspect you have stock valves with 3 angle grind.

 

I port matched my 5k to my manifold at 32mm.

 

No point running 'big' valves with stock cam. Save your monEy, go bigger lift, sidErafts and extractors. If you still have spare money, then by all means go for bigger valves.

Edited December 29, 2011 by philbey

[altezzaclub]

...and usually the exhaust is not the choke point, so bigger inlet only will make the greatest difference.

[Evan G]

normally you can go 1mm oversize without fitting a new seat. you have to get the whole package\

 

cam

compression

extractors

headwork

side draughts

[Mezz///]

My package is:

*weber 26/27 Wilson downdraft (should I swap for side drafts?)

*extractors

*2inch exhaust

*lumpy cam with unknown cam grinds,..much to my frustration lol any way for me to find out by looking at cam?

*head has been ported like crazy,removing all blockages to air flow and even oil flow.

*4k head looks like it's been shaved by the thickness indicator being half way..so compression may be higher than usual..I will ask machine shop to shave for more comp.

 

Thanks guys for your time :) much appreciated as always

[altezzaclub]

any way for me to find out by looking at cam?

Often numbers stamped on the back. Depends on the grinder.

 

*4k head looks like it's been shaved by the thickness indicator being half way..so compression may be higher than usual..I will ask machine shop to shave for more comp.

Measure the chamber volume and work out the compression ratio you have first!

 

*weber 26/27 Wilson downdraft (should I swap for side drafts?)

Ultimately the side draught manifold flows much better than the downdraught.

Edited December 30, 2011 by altezzaclub