Tuning Valve clearances

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Tuning Valve clearances

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Feb 1, 2010
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Melton mowbray
Hello once again,
My 650 engine is running a 35/75 sports camshaft and with that I got a leaflet saying valve clearances should be set at 0.25 for both inlet and exhaust.
How ever, I have larger inlet valves installed.
Would this alter what the clearances should be or just stick to the 0.25?

Cheers,
Alex
 
I initially had a 35/75/75/35 camshaft in my (well tuned) 650 engine, and valve settings on that were 0.20mm (8thou) inlet and 0.25mm (10thou) exhaust, as are the setting on the 40/80/80/40 cam I now have in it. HOWEVER, one would think that your cam's supplier would realise that it is not going into a standard engine and would have advised his settings to suit. My advice is to follow your suppliers advice (just for interest, who did supply it?)and go by what they reccomend. IF the engine sounds very 'tappety', you could try just closing the inlet clearance a bit.
Just for interest,when I worked at Radbourne Racing, we fitted NARDI 650cc kits to 500s, and the Nardi cam that was part of the kit was a 35/80/60/35 cam with valve settings of---0.25mm (10thou) for both in and exh.
 
I had a feeling you would be the one to reply thomas!

I've ran it with 0.25 on all valves and it seems to struggle a little, I've since swapped back to 0.25 exhaust and 0.20 for inlet as standard.
The cam was purchased though ricambio, and the leaflet given (photocopy) has a manufacturer's name of C.M.C di A. Stella, a quick google doesn't give much information other than it's an engineering firm in italy.

Alex.
 
I have tried to find out more information regarding C.M.C. Di A Stella, and as you say, they seem to be an engineering firm to whom the actual cam manufacturing work is contracted out to. It would seem that they do lot of work regarding transmissions etc.
 
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