Something for the engine specialists!

Sti8 engine after a crash, the belt timing was destroyed and 4 valves at right side went wrong.
Heads were disassembled ,the 4 valves were changed and tested the 16 of them not to lose compression.
Engine was prepared with forged pistons,rods etc.
For 2k miles has now a strange 1 valves noise at the right side. like a valve clearance is bigger.
Clearance was checked twice but the noise is still at the same level and frequency.
Oil used Shell Racing 10-60W.

Any ideas?

Thanks

Christos

 

Did you check all the valves in a drill to see if they are/were bent? It's quite a problem, as they have such thin stems that the valve spring will pull a bent valve back into the seat and actually create seal.

We always take them out spin them in a drill chuck to see if theye are really straight.
We have heard a noise on other engines that have come to us that sounds like wide valve clearance - only to find a slightly bent valve causing the noise.

The only way to check is to take the heads off again - if you are sure that the noise is INSIDE the engine.

Good Luck David APi Engines / APi Impreza
www.apiengines.com

 

Really interested David,
No we haven't checked them with a drill, but only checked if they seal well.
So this kind of noise can come from the slighlty bent stem hitting the valve "guide?
Can this cause a greater problem in the future if the faulty valve won't be changed?

Thanks in advance

Christos

 

Christos, Not really sure what makes the noise - just that we have heard it and after changing the slightly bent valves the noise goes away. That is after we have checked and double checked what appear to be correct valve clearances.

If you take eny piece of metal and continually bend it one way or the other it will snap.................... If a valve head comes off it will be like a hand grenade has gone off inside the engine.

David APi Engines / APi Impreza
www.apiengines.com