Thinner than usual valve pads

[Philippe-J.]

Next, and hopefully last, episode of the story:

I ended up ordering a new set of valves to Rob Beere Racing, I received them, I installed them, I measured the clearance between valve tips and cams, I inferred the needed new shims, and they all, but one, fall within the commercial available range
The thinner one is just 3 thou lower than the thinnest commercial one. Rob Beere advised me to grind or rub off a few thou.

This story confirmed that not only do Rob Beere provide the right stuff, they also are very helpfull

[Gfhug]

That’s good to hear Philippe. Keep us aware of how you progress

Geoff

[Stevemorris]

Sounds like you are getting there Phillippe!

So you are just replacing the valves? If it were me, and the head is clearly off at the moment, I would be inclined to fit new seats. If the new valves are giving you a 'close to the lowest' shim requirement, I would be much happier for long term fix if the shim requirements were either in the middle of the shim range or at the higher end? It's so so easy to do the seats now, so why wouldn't you?

Just to clarify, when Rob Beere says 'grind' the shim he doesn't mean on a grinding machine, this is a job best done by hand. It takes a long time but doing it 'cold' means the shim will retain its hardening. The shims loose this when they get hot on a grinding wheel..

Also, when you say 'commercially available' shims, assuming you mean from SNGB? They can supply shims down to 0.075" now (previously only available down to 0.085"). If you are having to take one of yours below the smallest available shim from SNGB I would say you definitely need to do the seats?

Sorry to appear negative but just trying to help!

Steve.

[Philippe-J.]

Hi Steve!

Thank you for your remarks & advise. I think I can confirm your points:
- according to the local workshop the original seats needed not to be renewed, just reground. They were not that worn. The issue I had appeared to be due to a wrong model for the valves. It was cleared off with the ones Rob Beere provided, except for one: it requires a 0.072" shim instead of 0.075" which is the lowest available at SNG. The others go up to 0.095". So for budget sake, I elected to keep my original seats.
- There was another reason. The above local workshop failed in the middle of their work for my engine. So they were out for a valve renewing job. The second workshop did an excellent job in surfacing the head, honing the cylinders and so on, but proved reluctant to renew the valves. I wouldn't want to force them in a job they were not volunteers in, would I?
- Yes Rob Beere advised to grind this shim by hand with sandpaper. I asked him if I should polish it afterwards, he said "No just rub it and hold in a valve spring retainer cap ". Your explanation is welcome, however.
- Yes I ordered my shims to SNG. They sell an extended range, even if not obvious to be found on their site (guess why I'm saying that). Rob (again) told me you can thin a shim down to 0.060". You can shorten the valve stem too, but it is a bit more difficult to stay perpendicular to the stem axis.
- I have to add that I change the guides, springs and tappets too.

Philippe