The last three engine I set up I set the cam timing as close as I could with crossover of the valves at 4 deg BTDC. They have all run well at that. The A Rapide with 5X cams, TTR with 5X cam and C rapide with Robinson stellated MK11 cams, but I never thought to check any of them with the opening and closing as outlined in “The Books”.
So I am messing with my Comet that requires some timing chest attention and have just replaced the cam with a Mk2 (Stock one out and a Robinson stellite one in) and set it up at 4 degrees, and for entertainment checked the opening and closings at 10 thou lift.
I get
In open at 44 BTDC (Richardson says Mk1 at 40-42 and lightning at 55)
In close at 83 ATDC (Richardson says Mk1 at 60-64 and lightning at 68)
Ex open at 46 BBDC (Richardson says Mk1 at 72-70 and lightning at 73)
Ex close at 62 ATDC (Richardson says Mk1 at 28-33 and lightning at 50)
I see if I move the cam back about 10 deg I would get 54, 73, 56, and 52, somewhat closer to Mk2 specs. But crossover would be 14 deg BTDC.
Anyone got any thoughts??
So I am messing with my Comet that requires some timing chest attention and have just replaced the cam with a Mk2 (Stock one out and a Robinson stellite one in) and set it up at 4 degrees, and for entertainment checked the opening and closings at 10 thou lift.
I get
In open at 44 BTDC (Richardson says Mk1 at 40-42 and lightning at 55)
In close at 83 ATDC (Richardson says Mk1 at 60-64 and lightning at 68)
Ex open at 46 BBDC (Richardson says Mk1 at 72-70 and lightning at 73)
Ex close at 62 ATDC (Richardson says Mk1 at 28-33 and lightning at 50)
I see if I move the cam back about 10 deg I would get 54, 73, 56, and 52, somewhat closer to Mk2 specs. But crossover would be 14 deg BTDC.
Anyone got any thoughts??
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