My 1974 mk2 has been rebuilt . The timing of the valves was set using the red marks on the cam wheels. The restorer decided to time the valves using the specifications from the manual. Has anyone any thoughts on how this changes the character of the performance of the engine?
My guessing is that we are…
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Previously david_evans wro…
Previously david_evans wrote:
My guessing is that we are talking about a PW3 cam here?
If it is a standard cam, then the timing marks should give the correct timing.
With a PW3, the standard timing marks give a valve timing 5 degrees early (advanced) Mick Hemming's timing figures involve retarding the cam 5 degrees. To do this, turn the cam sprocket one tooth anticlockwise (40 degrees) and turn the intermediate gear 3 teeth clockwise against the crank pinion (45 degrees) all degrees referred to here are crank degrees.
having run on both settings, I could not feel much difference but I was running in and reluctant to thrash it. Advancing the cam is supposed to give better performance and the standard setting is the advanced one but with the inlet and exhaust cams fixed relative to each other there is probably not much to be gained. An extensive correspondence in the accessnorton forum gave little guidance.
Hi David
Thank you for your information; I'll contact the engineer re. the cams, which are probably not PW3's and I'll obtain, for certain,his observations at the time of the rebuild.
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My guessing is that we are talking about a PW3 cam here?
If it is a standard cam, then the timing marks should give the correct timing.
With a PW3, the standard timing marks give a valve timing 5 degrees early (advanced) Mick Hemming's timing figures involve retarding the cam 5 degrees. To do this, turn the cam sprocket one tooth anticlockwise (40 degrees) and turn the intermediate gear 3 teeth clockwise against the crank pinion (45 degrees) all degrees referred to here are crank degrees.
having run on both settings, I could not feel much difference but I was running in and reluctant to thrash it. Advancing the cam is supposed to give better performance and the standard setting is the advanced one but with the inlet and exhaust cams fixed relative to each other there is probably not much to be gained. An extensive correspondence in the accessnorton forum gave little guidance.