I would like to work on my cylinders' timings on solidworks.

There is one dimension I don't have.

Any one knows the distance between the crankshaft axis and the original upper surface of the engine casing ?

Thanx.

Antoine

I'd use piston crown at TDC as reference. The measurement you're asking for varies from casing to casing, it also depends on whatever base gasket you may use, or on the machining of the casings.

64 to 64,5

(null)

I'd use piston crown at TDC as reference. The measurement you're asking for varies from casing to casing, it also depends on whatever base gasket you may use, or on the machining of the casings.

Sure, I'll take more or less this measure and adjust it to find the same timings annouced by the manufacturer, (here the 126/178° of the Polini EVO) then I will check how many millimeters I have to increase the exhaust port to have 30° blowout. (that's just a simulation I'll take the correct timings once I have access to my engine). I think it should be 1/1,5mm.

64 to 64,5

(null)

Thank you !

So when the manufacturers annouce the timings of their cylinder it will differ on each engine casing right ?

Bearbeitet 15. Dezember 201114 Jr. von keuk

Yes and no. Polini states that you need 1.2mm squish clearance, once you have that the port timing should be as per their manual. In real life cylinders are not overly accurate though, in the case of the Polini Evo you may expect transfer port timing of around 120 and exhaust port timing of 175 or thereabout more like. Iif cylinders are accurate you usually get a set of base gaskets with varying thickness to get to the squish clearance specified, once that is as it should be the port timing automatically is as intended. I'd do the same with your CAD modell. Start from the head down, add required squish clearance, place ports where you want them. Once you have all the parts in the flesh you compare your target measurements to real life measurements and adjust the latter accordingly..

Thanks !

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