Q4 exhaust valves

[corriedw]

Has anybody cut through the head of an old Q4 exhaust valve with a hack saw?

What I am trying to determine is if these valves are sodium cooled or not. The exhaust valves from a TS engine is not and is solid.

The head of a sodium cooled valve is hollow. In the hollow is strings of what look like lead. When the valve heats up to a certain temperature the lead-like sodium pieces change from a solid to a fluid, it may even a a later stage turn to a gas. But by changing form/state(langauge) the sodium use some heat energy and this energy is then not available to heat the valve further.

On a sodium cooled valve care must be taken in the way the valve is modified. You can easily weaken the valve and have the head break off during operation.

Mere interest, put some of the sodium bits in a glas of water and see it bubble.

[Suzumushi]

Has anybody cut through the head of an old Q4 exhaust valve with a hack saw?



As far as i know they are sodium valves
at least these in my q4 head are
And You will not be able to boil sodium as it melts in 98C and and boiling point at 883C :)

regards
w

[corriedw]

As far as i know they are sodium valves at least these in my q4 head are.

And You will not be able to boil sodium as it melts in 98C and and boiling point at 883C :)

regards
w

That looks perfect then, you guys reported exhaust gas temperatures of 900C to 970C. Combustion temperature may even be higher and after a short while the exhaust valves will have the same temperature?

I know the old 8v Alfas had sodium cooled exhaust valves. But the 16v and 24v engines do not. I have no where seen an official statement that says the exh valves on the Q4 are sodium cooled. It would be great if somebody could hacksaw the head of an old Q4 exhaust valve. Then I would know what to do with my valves and we could advise bloggers the same.

[AlfaJack]

no where seen an official statement that says the exh valves on the Q4 are sodium cooled.

They damn well better be for the £90 each:
http://www.walkers-garage.co.uk/shop/contents/en-uk/d16_01.html#p547

But then I found these on Tanc Barratt for £14 (I wonder if these are sodium filled or not..):
http://www.deltaintegrale.com/details.php?Clv=3&C1=2&C2=2&id=26726

A thread on the GC site:
http://www.guy-croft.com/viewtopic.php?t=2441

[corriedw]

Thank you AlfaJack, your thread clear that matter up. Thank you for the reference to Guy Crofts article, this is the kind of information I am after in my current research. The Q4 engine is new to me and has its important differences to the rest of the family.

Normally the performance guys do not work much on the exhaust valve and seat as the gains are small here. But with the sodium cooled valves it means no material is to be taken from the top of the valve. You can leave the 2mm seat on the valve and then above that machine a groove, 2mm horisontal in and vertical up with a radius in the corner. This will open the valve a little more in the begin and opening of the cam action without weakening the valve.

[corriedw]

My next question: Has the standard Q4 engine bronze valve guides in the head.

[Brul(tm)]

Thank you for the reference to Guy Crofts article

If you want to learn about engines and tune/improve them, buy his book :thumb: All the aspects of the engine will be discused in there.

[Steve Webb]

If you want to learn about engines and tune/improve them, buy his book :thumb: All the aspects of the engine will be discused in there.

I do believe there is an electronic file of the book floating around on the internet somewhere.

And I think a hard copy of the book is hard to come by these days, and expensive.

[Brul(tm)]

I do believe there is an electronic file of the book floating around on the internet somewhere.

And I think a hard copy of the book is hard to come by these days, and expensive.

I have the digital out dated version from the net somewhere.
When you are planning an engine project, I guess the book From Guy is a must have. Or not, when you find out there's more to it ;)
Anyways, for some maybe a bid to expensive

Currently he's planning a workshop version of the book, with updates if I read it correctly. With a discount if you sign up now (+TAX & postal coasts).
For details take a look on his forum.

[corriedw]

If you want to learn about engines and tune/improve them, buy his book :thumb: All the aspects of the engine will be discused in there.

Brul I paid for his black and white version that will be printed in june/july.

There are 2nd hand, colour ones available on Amazon for $235.

I have done most of what he is doing before, learning by having an expert do a head and then later use the principles on other developments. I have not used the guys with flow benches, as in SA they do not very well compared with some experts.

Each of these guys have a method or plan for what they do. But some plans work on some engines and not on others, where a different methods is needed.

I like what Guy Croft is doing, maybe because I did it similarly, I have tools to do the same cuts. But it does not always work. Let me explain. The power on head work lies in the valve and seat up to the point where the port can not sustain the flow anymore, which is above street use. Some guys will say for street use just use more cam. And in the case of a turbo motor, more pressure WILL get more air into the head even if it flows badly as a normally aspirated engine.

Guy use square angles on his valve seats 70deg/45deg/30deg The standard from the Lancia manual says 60deg/45deg/30deg which may flow better due to a better angle onto the seat, but will match up with a smaller port. These angles on the valve seat, worked well on all the(non competition) Alfas I modified and my Ducati and some other cars.

But the same method gave me zero gains on a 1800 sohc GSI Opel (Vauxhall). On my 2000 GSI with same design engine I got great gains when the head was done with round seats by Roger Taylor(ex Cossworth). He used a tapered entry to a small(narrow) round seat and a penny on a stick valve.

I know a guy, who used to be in charge of the racing department for Nissan SA, very well. He went private as Maus and prepared many cars for ralleys. He use a parallel entry into a wider round valve seat and a valve that look like a blown-up umbrella. This worked great for the Nissans and even one of my Uno turbos. But it added no power to an Alfa TS.

So there will be people with slightly different plans who are experts with different makes of engines. I have not used and do not know exotic materials for valve seats that I have seen in Guy's pictures.

[corriedw]

I have the digital out dated version from the net somewhere.

I would be grateful if you could pass that on in a private e-mail?