Performance valve selection.

[gav240z]

I just stumbled across some performance valves on ebay to suit the L-series engine.

 

They appear to compatible with the L28 head (early at least). However my questions are about dimmeter they are the same size for the intake as a stock L28 head but the exhaust diammeter is larger. Is it common practice to install larger valves for both intake and exhaust or just enlarge the exhaust valve?

 

This is the letter I wrote to the seller on ebay below.

 

http://cgi.ebay.com.au/DATSUN-Nissan-L16-L18-L20B-BIG-O-S-STAINLESS-VALVES_W0QQitemZ4633317837QQcategoryZ102557QQrdZ1QQcmdZViewItem

 

Hi mate,

Yes I had a feeling they were the same. I just cross checked my book ?How to modify your Nissan/Datsun OHC Engine? by Frank Honsowertz and it appears they are suited to the early L28 head?s most likely N42, N47 but not suited to the deeper chamber P79/P90?s.

 

The intake diameter is the same size as a standard L28 head but the exhaust side is slightly larger by about 3mm.

The reference I have says L28 valve specs are as follows: Intake 44mm and exhaust 35mm.

 

In the description it says OAL 4.62? is this valve length? My book says the length of the valves is 4.53? for intake and 4.57? for exhaust.

Not sure if this can be corrected just using thinner lash pads or what have you or have I got OAL totally wrong?

 

I?m very interested in these valves however I want to verify they are the right choice first and I?d also like to know where I can get the remaining 4 that I will need to complete the set.

 

Cheers,

Gavin.

 

Any help would be appreciated.

[kalium]

Is it common practice to install larger valves for both intake and exhaust or just enlarge the exhaust valve?

 

I have zero experience with measuring the effects of different size valves, but I came across an interesting thread on hybridz the other day where a fellow gave Rebello his head with some oversived valves and std Valves, and Rebello opted to put in the std size intake and 1mm oversize exhaust.

 

 

[stevo_gj]

Kalium you're delving into necromancy with this thread.

 

Reckon you could post the link to the HybridZ thread?