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May 12, 2018 8:09 pm
May 12, 2018 8:09 pm
Subject: Re: Tappet clearances - why the variation?
Just joined the Club & seen this. A similar discussion came up on the E Type forum a while back; Jaguar changed the cam profile at some point, and altered the clearance from 4 I & 6 Ex, to 12-14 for both. I questioned why they had found it necessary to double the gap.
The consensus was that otherwise the valve timing would be wrong with the new cams. I made myself unpopular by refusing to buy this explanation. I cannot accept that Jaguar would re-design the cam and then say "Oops, now the timing is out but if we open up the gaps we can get it back to where it should be."
Others suggested that they opened the gap because the previous gap had been too small. Once again, I find it impossible to believe that it would take forty years for such a shortcoming to become apparent.
Still no idea why they did it though - it remains one of life's mysteries!
Just joined the Club & seen this. A similar discussion came up on the E Type forum a while back; Jaguar changed the cam profile at some point, and altered the clearance from 4 I & 6 Ex, to 12-14 for both. I questioned why they had found it necessary to double the gap.
The consensus was that otherwise the valve timing would be wrong with the new cams. I made myself unpopular by refusing to buy this explanation. I cannot accept that Jaguar would re-design the cam and then say "Oops, now the timing is out but if we open up the gaps we can get it back to where it should be."
Others suggested that they opened the gap because the previous gap had been too small. Once again, I find it impossible to believe that it would take forty years for such a shortcoming to become apparent.
Still no idea why they did it though - it remains one of life's mysteries!