thedoc Posted March 8, 2011 Share Posted March 8, 2011 I am in the process of fitting a hotter camshaft to my Spitfire 1500. I am also changing to duplex chain drive (no vernier adjustment). How accurate can I expect to get the camshaft timing with the setup I have? I should be aiming for maximum lift at 110 degrees ATDC but this is proving a little elusive! :( Any suggestion please? Link to comment Share on other sites More sharing options...
mikew Posted March 8, 2011 Share Posted March 8, 2011 Don't forget the sprockets can be fitted in 4 different positions, giving variable offset. Firstly rotate the sprocket by 180 degrees and try again - note the variation, then you can refit the sprocket "back to front", and again 180 degrees out, which is a total of 4 positions all with the timing different. twas a clever part of triumphs original designmike Link to comment Share on other sites More sharing options...
Richard B Posted March 8, 2011 Share Posted March 8, 2011 mikew wrote:Don't forget the sprockets can be fitted in 4 different positions, giving variable offset.Didn't think you could on a duplex, only on the simplex. :-/ Link to comment Share on other sites More sharing options...
thedoc Posted March 8, 2011 Author Share Posted March 8, 2011 Richard B is right so adjustment is limited-how near the ideal setting might I expect to get? Is it that crucial? Link to comment Share on other sites More sharing options...
drofgum Posted March 9, 2011 Share Posted March 9, 2011 Hello,If the duplex sprockets are drilled in a similar manner to the simplex; turning the sprocket 90 degrees should adjust the timing by 1/2 tooth. If my count is right that is a bit over 4 degrees. Cheers, Paul Link to comment Share on other sites More sharing options...
rhodes Posted March 9, 2011 Share Posted March 9, 2011 Don't think so. 4 degrees cam maybe, which is 8 degrees crank. Link to comment Share on other sites More sharing options...
drofgum Posted March 10, 2011 Share Posted March 10, 2011 Rhodes,You're right I forgot to double for crank degrees. Cheers, Paul Link to comment Share on other sites More sharing options...
Velocita Rosso Posted March 10, 2011 Share Posted March 10, 2011 Im sure the timing should be 103 degs for a FR83 cam and the Vernier Duplex timing gear has cap screws in slotted retaining holes to fine tune the settings. So no need for sprocket removal etc Link to comment Share on other sites More sharing options...
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