I have just had some larger, lighter valves made for my SS project. The question i have regards valve clearance is the gap between the valves on the cam overlap, has anyone had any experience of closing this gap up, and if so how close can you dare go? a figure that is banded about is 40thou but i am already closer than this with success, and running to 10.5k on occasion. I am currently working on the inlets, std being 89g, new big valve (45mm) has come in at 81g, so 10% ish weight saving. there is more that can be removed by gun drilling the stem but at the mo i am concentrating on flow and clearances. Any suggestions of a minimum clearance without a big bang! i currently have approx 35thou between the valves with new valves and guides. I fully understand the implications of this when there is major miles on the dial so maybe a figure to take this into consideration as well? Your help and positive comments are appreciated.
can i ask what inspired your choice of size of valve have you seen it done before what combination with the exhaust valve is possible with the size of the bore…….and of course the overlap to avoid contact. Presumably its an air cooled what 1000cc? who else has built one……..
You can ask... Valve size was dictated by what will fit, yes its been done before, and done before by myself. exhaust valve work to come as I am concentrating on the inlet first. The motor is from a 95 900 SS Air cooled two valve, 94mm bore. who else has built one? quite a few I think, with varying results.
After a lot of jiggery-pokery i have got the valve to valve clearance to 37thou, this is without pocketing the valves, next stop "the dyno", i just have to keep everyting crossed to stop things getting crossed.
