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The valves you have mentioned are only just outside spec.
You can do as you have mentioned.
The valve clearances are not your cause though.
I would be inspecting the ignition system and the carburettors.
Multi Webered engines are very prone to these phenomena.
A thicker shim makes the clearance smaller.
So, if you measure .35, and you want .30, you add .05 to the current measured shim thickness.
Then I would measure them all again.
Your cam of 8.24 - .32 would give you 7.92 valve lift.
Any cam lift specs for shim/bucket DOHC engines will have to take valve clearance away for true valve lift.
Did you measure this with a dial indicator at the shim/bucket?
I would shoot for the middle of the range for a customers car.
If it was my own I would shoot for close to minimum.
I would check my own more often though.
Valve faces and seats don't wear as bad these days, compared to the 50s to early 70s.
Technically the shim should wear at the same rate as the valve seat/face.
If the shim wears faster then the clearance gets larger.
I rarely see engines that have clearances that tighten up.
That's why I would go for the middle of spec.
I run two of own cars at near minimum spec, since I'm chasing power.
I don't mind checking them every 1000kms.
I know it is hard to get say .33 as a target, just get them as close as you can to mid spec.
You can't go wrong doing it that way.
Too tight burns valve seats, too loose wears seats and shims, shims more than seats.
Rattling valvetrains also wear cam lobes, all things to think about.
That's why mid spec is safe.
Yours has DCNF Webers?
How are going with your Ferrari?
I hope my advice has been of assistance to you.