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Triumph Repair/Spitfire MK3 Camshaft timing


Dear Howard,

Good day!

I am currently doing a restoration on a MK3 FD engine which
has a 25-65-65-25 original old Stanpart camshaft.I am checking the valves (exh/suction)timing for opening/closing in degrees with 2 magnetic dial gauges and although I have set the overlaping correctly at TDC, the suction valve instead of closing at 65 ABDC it closes at 65 BBDC. The exhaust valve timing is correct.
There is something wrong with the camshaft. Have you ever experienced such a problem with an out-of-range camshaft ?.
The engine is a old unit I found in abandoned here in Greece.

Your help will be appreciated.

Best regards,
Andreas Andriopoulos

Hi Andreas,

My books show the Euro versions for the FD engine to be the 25 - 65 , 65 - 25 degree cam for the Euro version MK III spitfire with engine number prior to 25001. But even a USA version was 10-50 50-10 degrees so neither would match the cam you have. The later enignes were 18-58 58-18  for US and Euro versions. So neither matches what you have. Even a special regrind cam for a turbo charged engine wouldn't close that early. Spliting overlap is the correct timing for all of them so it is not that you have the timing wrong.

It sounds to me like a cam grinder was drinking while working that day. I can't think of any reason to close an intake valve that early unless they hate horse power. Even a tractor engine wouldn't do that. Even if it was for a marine engine that rotated backwards the other valve timing would be off too. It sounds to me like a bad cam regrind.


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Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

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