Never mind the 'Crossflow Tappet Adjustment' thread, now it's called the 'Engine Seized Thread' UPDATE

[nickh7]

Missed a gear by the sounds of things, I cant see you're liable for this.

 

Nick h

 

Its Yellow And Black and Makes me 😬here

[BrianHorn]

Just seen the damage inside.

 

Piston is embedded with bits of valve so that needs renewing. Are Accralite 83.5mm pistons available singly?

Bore has escaped damage thankfully

 

Builder suggests a whole new set of valves. I take it this will mean springs, collets etc and where can I get them from? Burtons or Caterham or Redline?

Also thinking of rocker arms with shiny new faces as the valves will be new.

2 new conrod bolts also suggested.

 

He's going to look at the bottom end tomorrow to see if there are any nasties lurking down there but we think all is okay as there was plenty oil in the sump

 

Anything I have forgotten?

 

Brian

 

Common sense is in spite of, not the result of, education.

 

--Victor Hugo

 

[Neal Worth]

*eek*Ouch! That's a bit of a mess.

 

Burtons should be able to supply you with all the parts needed. They list the accralite pistons and they are priced individually.

 

Hope all goes well with the rectification.

[McBreadhead]

Brian,

 

Just been to Burtons today and they are refurbishing my xflow head for approx £325 leaded or £425 unleaded and for that are replacing all new valves, new (duplex) springs, new bronze valve guides and valve stem oil seals. Incl is warp test, crack test, pressure test new valve seats. Admittedly it's a Stage 4 so not sure if they charge differently for (I assume) standard xflows.

 

However you may want your rocker gear checked if any strain has resulted from the valve incident.

 

Speak to Guy who's the crossflow expert and has a 195bhp 10,000rpm screamer.

 

Good luck

[BrianHorn]

Yesterday I spoke to the new owner/driver at the time of the incident and he swears blind that he did NOT over-rev the engine at any time. Nor did he miss a gear etc, etc.

That being the case, is it therefore possible that the valves just 'failed' through metal fatigue eg? It's not something that I have heard of before.

[Nifty]

You don't lose two valves on the same cylinder, at the same time, through metal fatigue ❗ ❗

 

Keep off the straight and narrow 😬

[McBreadhead]

Brian,

One of my exhaust valves was about to let go when I caught it just in time. I am no expert so others may disagree but this is what the man at Burtons and I discussed:

 

The inner pair of cylinders run a bit hotter than those on either side so the valves tend to go first, but exhaust before inlet. It could be that the exhaust valve has let go and taken the inlet with it. Mine run 2 piece friction welded valves and they have failed thru fatigue we believe all around the weld.

 

It would be worth trying to establish if there is a regular circular crack on the exhaust valve, roughly 1cm dia which is where mine failed. Is it possible the cylinder was overfuelled thus making it run hotter?

 

Depending on what state of tune your engine is I have been advised up to Stage 2 then 2 piece valves are OK; beyond you should go to single piece items. Having said that another source said some F1 teams use 2 piece valves but I cannot honestly believe that given the revs and fatigue they would be subjected too.

 

Burtons do both Accralite and Cosworth pistons from circa £150 ea - you will need to think about balancing the new one into the fold however.

 

Nick