GT6boy Posted August 25, 2008 Share Posted August 25, 2008 If my TT Fast Road 83 cam shaft has an installaton figure for No.1 inlet valve at 103 degrees, is that the correct figure? Mine appears to be fitted at an actual 105 degrees. Given that it is not like the old Triumph cam profiles and symmetrical in valve timing (eg. 25-65 65-25), but asymmetrical (37-63 74-28), could it be that mine was installed slightly later at 105 degrees: as the difference between the actual instal figure for the inlet valve was 105 and the actual for the exhaust is 108.5 degrees, they may have split that difference and added it to the TT install figure?!? :-/ It could just be that the cam was timed in wrong, but I don't want to assume, it may be that fitting this type of cam required a little lateral thinking? Anyone know if that makes sense having it at 105 degrees on the inlet, even though TT wanted it 103? Link to comment Share on other sites More sharing options...
Deleted User Posted August 27, 2008 Share Posted August 27, 2008 http://www.mintylamb.co.uk/?page=camcompare.htm#I think it may be set up wrong! But you would have to speak to whoever installed it!I checked mine and it was a couple of degrees out and it ran better once set up in the correct way! Now running TH5!Hope this helps!Rob Link to comment Share on other sites More sharing options...
Richard B Posted August 28, 2008 Share Posted August 28, 2008 You haven't got a Duplex cahin have you? There is a more limited set of (teeth) options with the Duplex compared to the Simplex as the Duplex gear wheel is non-reversible.Simplex Tooth, 1/2 tooth and 1/4 or 3/4 toothDuplex Tooth or 1/2 toothor have you got a very nice vernier setup? :P Link to comment Share on other sites More sharing options...
thealligator Posted August 28, 2008 Share Posted August 28, 2008 Richard_B wrote:You haven't got a Duplex cahin have you? There is a more limited set of (teeth) options with the Duplex compared to the Simplex as the Duplex gear wheel is non-reversible.Simplex Tooth, 1/2 tooth and 1/4 or 3/4 toothDuplex Tooth or 1/2 toothor have you got a very nice vernier setup? :PSaved me the typing. 8)Reverse the timing gear Link to comment Share on other sites More sharing options...
GT6boy Posted August 28, 2008 Author Share Posted August 28, 2008 An update. 1st off, thanks guys for the input :). The cam is indeed timed in at No.1 inlet valve at 105 degrees, which ain't correct. The fitting instructions say 103. It does currently have a duplex chain and standard duplex wheel(that was news to me, I thought it was a single chain hiding under there, as it is a 2 litre :B). My initial missive here was wrong- it is a symmetrical cam. The guy who fitted it some years ago (5+?) purposely timed it at 105 thinking it was 'best practice'. I have at home and will be fitting a vernier wheel, so I can dial it in 'Exact-a-mundo'. This will be done initially with the head still off, then at the valve just to check this doesn't affect the cam install/function timing through the valve gear etc. If there is a difference with the head on, I can then adjust the vernier wheel accordingly, without re-course to taking off the wheel and trying a cog this way/that way etc. Then it's off to Castle Combe for the Eurofest, to try it out fo real with the revised timing! ;D Link to comment Share on other sites More sharing options...
GT6boy Posted September 4, 2008 Author Share Posted September 4, 2008 Vernier wheel fitted and the cam was timed in at 103 spot-on 8). Timing then checked at the valve collet and found to be 103.5-75, so left at that. After gettin it all back together again today, I wasn't able to go for a good run as the thermostat is getting sticky in operation, so I don't want to fry the new cylinderhead gasket. Ill get a new thermostat tomorrow. :) Link to comment Share on other sites More sharing options...
GT6boy Posted September 6, 2008 Author Share Posted September 6, 2008 Well there is a surprise- now the cam is installed at the correct figure, a trip to and around Castle Combe today showed that the cam having previously been fitted retarded, had indeed pushed the available powerband further up the rev range. My car now has more power lower down the rev range and accellerating out of corners was a far more pleasurable experiance :). Woo-hoo ;D! Link to comment Share on other sites More sharing options...
sparky_spit Posted September 10, 2008 Share Posted September 10, 2008 Well done Bruce, nice one! I love this sort of thing where a previous owner or "specialist" has done something not quite right, just left it like that and lived with it. Then you spot the mistake and correct it for the better. It's almost like getting a performance gain for free. Very satisfying. Link to comment Share on other sites More sharing options...
GT6boy Posted September 10, 2008 Author Share Posted September 10, 2008 Nice of you to say Mike. Your spot-on there. Car and perhaps more importantly my understanding of how it works has improved: EDUCATION! ;D Credit where its due, it was our man in Estonia who initially suspected this and brought his experiance to bear with a on-the spot hunch type diagnosis in the dark, after driving the car and 'listening to the engine'. A quick whip off of the rocker cover and operation of the valves in relation to the crank pulley timing marks appeared to support his initial theory of the cam being timed incorrectly- therefore the engine not running and sounding right. So I can't claim any glory for this one :B. There is no substitute for experiance :). Link to comment Share on other sites More sharing options...
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