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Valve question

Started by Trevor Williams, August 26, 2008, 08:14:09

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Trevor Williams

Just interested in whether anyone else has had either the heads of the valves coming off, or little nicks out of the valve head surface? One head and piston destroyed in my race engine this year by the latter, as well as the same happening in an engine I leant out last year. Both had the waisted stem valves
Trevor
Some days, it's REALLY difficult being me!

Paul Robertson

Inlet or exhaust trev?
We could send it to mike and see what the metallurgy boffins come up with.

mark turner Whitwell Motorsport

We have had to replace both inlet and exhaust valves after just two hours of running all this season!
We have had problems with both the standard stem and the waisted stem valves each with different
faults. ???
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Martin Harrold

We are not quite sure why, possibly over-revving by a newbie, but in testing at Snet, the head of one valve, standard I guess but Dicky knows exactly, came off and ended up coming 99% out of the crankcase on the other side. Pity it is not just a new valve that's needed.
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Pete Sparrow

We had an exhaust valve head fall off, wasted stem.
Car 29 and 64 also had the same problem with wasted valves.
It does seem like a rerun of 2004 the difference being that there are failures of both wasted and standard valve, the former being more prone to this having a flatter back face and thinner stem. Valve spring rate???
The older I get, the more rubbish I talk
(and the more pills I take)

Mary Lindsay

Last year we had the same problem with the head coming off a valve and shot blasting the inside of the engine.
Mary Lindsay
Car no 42.

mark turner Whitwell Motorsport

Sorry about the spelling mistake :o
All season we have been trying different valve spring rates and still suffer with the same problems.
Make the springs too strong and the valve heads fall off or distort, make them too soft and the valves
bounce at high-ish revs and you end up with the same results! DEAD ENGINES
Is it not about time this problem was sorted out properly, or do we all go and have valves made from
stainless steel.
Most people know what the fault is!! :-X Let's get it sorted out now so that everyone can have some
reliability(for a change).
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Andrew Bull

Tell me mark, what is the problem, because i dont know? your post infers that you know someone who knows or you know yourself!

PS how did you get on with the chopper?

Cheers Bully
Andrew Bull
Tête Rouge Racing with Habitabull & Propolis
Rookie Champion       2022
team champions         1998 2000 2008 2009 2013
24hr winners               2005 2006 2009 2010 
championship winner 2006 2007 2008 2009 2010 2011 2013

Andrew Bull

Do we actually know the problem?  or are we just extrapolating from talk that occurrs.  Is the Technical committee involved in trying to sort out whether there is a problem. (I know Paul Has replied)

Is it just non regular drivers putting 9000 rpm on them!

Lets gather the info correctly and do some proper diagnosis work. Draw up matrix of what failed and how its installed. 5 Why's!!  root cause analysis, fish bone.... whichever technique you choose.

More information should be provided to try to obtain the best possible picture for analysis.
New or old valve?
Which valve? NS / OS inlet/ex
Manufacturer of valve?
What type of valve?
Standard / modified valve guide?
With which driver did it fail? (could have been buzzed as martin suggests?)
Springs when installed? New/ 2nd hand/ double?
Normal rev limit for your setups? 
Valve Clearances?
Normal operating temperature of your engine?
Cam Number? (Could be a dodgy batch)
New cam or 2nd hand before grinding?
etc etc.


Mark, have you had problems with one particular pair of heads or have all your engines required this level of maintenance?

Of course, if somebody else actually knows what the cause of the problems is, then please shut me up.

For further info, i ran a full blown race engine on the road (was actually 10thou under barrel-barrel size) with race cam, rim flow & wasted stem valves (machined by Bas) 2nd hand springs and double springs with standard, full length valve guides in ported heads. This engine did over 10,000 miles at pretty much full chat. I never drove it slow and my gear changes usually occurred when the engine wouldnt rev any more.  The cam has since been removed and is now in one of our race engines as it was deemed good for use.  The valves are fine and have been ground in with minimal effort and a standard cam has been installed.  I cant stand the noise the cam makes with no backlash gear. 

If we want to do then lets do it right.  If you want to jump to conclusions on heresay and talk then ignore me. 

Best regards and see you at Mallory

Andrew Bull
Andrew Bull
Tête Rouge Racing with Habitabull & Propolis
Rookie Champion       2022
team champions         1998 2000 2008 2009 2013
24hr winners               2005 2006 2009 2010 
championship winner 2006 2007 2008 2009 2010 2011 2013

Paul Robertson

Some might say it's the c word.











must wash my mouth out

Andrew Bull

Andrew Bull
Tête Rouge Racing with Habitabull & Propolis
Rookie Champion       2022
team champions         1998 2000 2008 2009 2013
24hr winners               2005 2006 2009 2010 
championship winner 2006 2007 2008 2009 2010 2011 2013

mark turner Whitwell Motorsport

Unfortunately all of our engines have suffered in varying degrees.All the valves we fit are new with new
valve springs (inners and outers). After only two hours of track time we are seeing upto 30% leakage
through valve distortion.It is now getting very tedious and expensive.Ramp speed on closing is probably
a major cause!
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Paul Robertson

Or valves not up to the job of racing!!

mark turner Whitwell Motorsport

I had a conversation with another club member last weekend who is running stainless steel valves and has
done so for several seasons and claims to have had no problems since fitting them!Could this be the answer
or do we investigate further?
Bully, i have sent the file to my engineering works, just waiting for price and time scale.
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Mary Lindsay

QuoteIs it just non regular drivers putting 9000 rpm on them!
You are joking of course!
We are very careful not to over rev the engine especially as it is a 24 hour race. Anyway I don't think ours would have been capable of those sort of revs!