'Sodium' Exhaust valves - what size? 29mm??? NOT!
Turbo Mini Forums

A typical case of going off what everyone else had always said.
I assumed the sodium vales were 29mm - becuase that's what everyone alwyas said they were.
I was surprised when i measured one over the weekend, and found it was 30.3mm. So i measured another, and another, and another; 10 in total. All 30.3 mm give or take 0.05mm.

I know there were two 'versions' of sodium valves - different collet grooves was the main identifier. Maybe the 'early' mk1 turbo had 29mm valves, and this 'designation' just stuck, in the same way that the 'turbo' crankshaft was nothing special... But we all know that post 86(ish) cranks are mostly the '6581' rather than the '6232'...

D

yet another good piece of information!

Its amazing how much "common knowledge" is just plain worng!

Top work Dave!!!

Alex

AlexF

Hi Dave!

The numbers are steel material codes??

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

good work for the valves Dave , I will have to check mines. 6581 cranks in place 6232, what is the difference?
cheers
fab

good work for the valves Dave , I will have to check mines. 6581 cranks in place 6232, what is the difference?
cheers
fab

good work for the valves Dave , I will have to check mines. 6581 cranks in place 6232, what is the difference?
cheers
fab

No-one really knows about the differences in the cranks Fab - i suspect it is a different material (why make a new forging, or insert for the forging if all you're doing is changing heat-treatment) and judging by the appearance, and the fact they seem to last so long (mine is still std/std for example!!!), they probably have some 'extra' heat-treatment process...

I'd appreciate it if everyone could measure their valves and confirm what they find the head diameter is!!!!

Ive got a couple of heads in the garage, ill have a check.

mmmmmmm
mine all seems to be 29 ,29, 29 ,29

Everyone knows that instructions only have to be read if the thing doesn't work....

, unlucky, my heads have the 29mm ones

I measured mine yesterday. They are in the head and I hope that measuring was right.
So, mine are more 30mm then 29mm, but I will take them out and chek again to be sure.

Edited by gregor on 16th Mar, 2004.

strange.....

very strange...

stock valves!

Will get part numbers tonight...

do they have part numbers on them?

I haven't cleaned mine up, but I have a couple of heads worth I can check as well properly tonight.

Alex

AlexF

Ok Guys I?ve just checked mine from a fairly new head and the Exhaust is 29.4mm (TAM1361) and the Inlet is 33.25mm (TAM1330 M) if that?s any help.

Karl

Edited by Doodmeister on 17th Mar, 2004.

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

Forot to not the numbers, but i measured more goosed valves from the depths of my 'shed' and found them to be 29.3-29.6mm...
Maybe i've just been lucky and have a batch of overmachined ones?

Incidentally, the 'inner' diameter of the seat angle machined in the valves is the same on almost all the valves... so in reality, the gain of having a larger head is not actually gaining anything...

Looks like it might just be another Leyland screwup after all... oh well!

That reminds me on a Toyota D4D (is it?) engine I just saw. The valve seat was 2mm from the edge of the valve. The solution was to make the valve 4mm smaller which improved flow and grunt. It would also be possible to move the head valve seat of course.

Try telling that to people. A smaller valve will actuall make more hp... That won't get you many pub-points.

I hate Toyotas anyway. Let them be crap.