DJB350Z Posted September 19, 2022 Report Share Posted September 19, 2022 Hey, I'm in the market for a timing cover and although it looks like compatibility is good between Triumph models I've noticed they have different tabs on the face of them sometimes. 1. What are the tabs for? 2. Are the differences significant in some way? As an example, here's 2 pictures of a couple on eBay right now. Link to comment Share on other sites More sharing options...
johny Posted September 19, 2022 Report Share Posted September 19, 2022 Just different indicators intended to show the position of piston 1. However the first can be used with any crank pulley ie one that has multiple marks or just one whereas the second cover can only be used with a multiple mark pulley. If you try to use the second with a pulley intended for the first type you'll only be able to find top dead centre of the piston and not its degrees of rotation before that point you need to set the ignition timing.... 1 Link to comment Share on other sites More sharing options...
Josef Posted September 19, 2022 Report Share Posted September 19, 2022 Johny’s right, but I’m pretty certain engines were shipped with single pointer cam covers and singly marked pulleys. Both my 13/60 (which is pretty original) and Mk3 Spitfire (which isn’t!) are like this. Though if you’re choosing a replacement I’d probably go for the later type, your first picture, as it is a bit more user friendly. Link to comment Share on other sites More sharing options...
DanMi Posted September 20, 2022 Report Share Posted September 20, 2022 They changed the pointer when they went from small to large crank (4 cyl), the hole is a different size so they are not interchangeable as the crank pulley is a different diameter and the crank is a different diameter so the pulleys are not interchangeable either. single pointer = early small crank 1 1 Link to comment Share on other sites More sharing options...
DanMi Posted September 20, 2022 Report Share Posted September 20, 2022 Also the early cars (spits at lest) had a vernier on the distributer so that you set the timing at TDC and then advanced a certain number of click to get the correct timing, so you didn't need the degrees, later didn't 1 Link to comment Share on other sites More sharing options...
johny Posted September 20, 2022 Report Share Posted September 20, 2022 4 hours ago, DanMi said: They changed the pointer when they went from small to large crank (4 cyl), the hole is a different size so they are not interchangeable as the crank pulley is a different diameter and the crank is a different diameter so the pulleys are not interchangeable either. single pointer = early small crank Yes it looks quite confusing as Rimmers list 4 different part numbers for Herald timing covers and theres obviously different seal sizes and pointer designs. Certainly my Vitesse cylinder cover has a single pointer but I think is the same cover as the large crank 4 cylinder type so before buying any cover you need to check both pointer suitability AND seal size... Link to comment Share on other sites More sharing options...
DanMi Posted September 20, 2022 Report Share Posted September 20, 2022 rimmers only list 2 herald 1360 gk and then earlier, they have 4 as 2 are new and superseded by the 2 used versions. I'm not certain of the 6 cylinders Link to comment Share on other sites More sharing options...
johny Posted September 20, 2022 Report Share Posted September 20, 2022 For Heralds Rimmers list all of the following for 13/60 GK engines but thats an error as the third one here definitely isnt: 217790U used, available (single pointer, large seal?), 217790DOLU used, available (multi pointer, large seal?), 201311U used, available (single pointer, early type with small seal?), 217069 new, not available (unknown pointer, small seal?) Link to comment Share on other sites More sharing options...
DanMi Posted September 20, 2022 Report Share Posted September 20, 2022 yes the last one looks like early GT6. Rimmers are not the best for getting the parts correct, why they have one listed as dolomite, when there is no difference is anyones guess Link to comment Share on other sites More sharing options...
johny Posted September 20, 2022 Report Share Posted September 20, 2022 Believe DJB has a 1973 GT6 which presumably has a multi mark pulley so I guess any cover with a large seal should be suitable. Course would then be a good idea to confirm that TDC of piston one corresponds with the indications... Link to comment Share on other sites More sharing options...
DJB350Z Posted September 20, 2022 Author Report Share Posted September 20, 2022 2 hours ago, johny said: Believe DJB has a 1973 GT6 which presumably has a multi mark pulley so I guess any cover with a large seal should be suitable. Course would then be a good idea to confirm that TDC of piston one corresponds with the indications... I have a 1973 GT6 with a 2.5 PI engine. I've purchased a multi mark cover which was cheap enough to take a punt on. Will report back with findings but fingers crossed the seal diameter is ok. Thanks again for insights. Link to comment Share on other sites More sharing options...
johny Posted September 20, 2022 Report Share Posted September 20, 2022 should be ok but of course you have a duplex cam chain so I wonder if the tensioner is the same... Link to comment Share on other sites More sharing options...
DJB350Z Posted December 24, 2022 Author Report Share Posted December 24, 2022 Well it arrived long ago now, and it was in a bit of a sorry state. I cleaned it up best I could, replaced the oil seal and tensioner and then finished it with a coat of paint. It's not perfect but hopefully usable. The degrees marked on the tab are barely visible, but I hope between that and the multi mark pulley I have I can make it all work. Link to comment Share on other sites More sharing options...
johny Posted December 24, 2022 Report Share Posted December 24, 2022 The most important thing is that it seals well on the block. The timing should be set by advancing until you get the pinking right with the fuel youre using👍 Link to comment Share on other sites More sharing options...
Josef Posted December 24, 2022 Report Share Posted December 24, 2022 A printable degree wheel can help you mark up the pulley and / or cover to your liking too. Though I’d also do the dynamic timing as Johny suggests, it is something that requires a bit of feel, so some numbers do help you know if you’re in the right ballpark to start with. Link to comment Share on other sites More sharing options...
JohnD Posted December 24, 2022 Report Share Posted December 24, 2022 Four cylinder Triumphs had solid front pulleys, that had TDC and/or timing marks on their rim. But the sixes had a damper pulley. This was deemed necessary, as the longer crank would have lower harmonics, into the projected rev range. The pulley had a solid hub and an outer 'inertia' ring, held together by a band of rubber. The compliance of the rubber would absorb energy and damp it out, to prevent Torsion vibration. The rubber was little different from tyre rubber, and in the heat and oil of the engine bay, it tends to deteriorate. In a survey, up to 20% of dampers had lost damping capability and some can lose adhesion. If that happens, the outer ring turns and the timing marks become nonsense! Always worth checking that TDC by pulley coincides with TDC as found by, say, a piston stop. I can test a pulley for damper function, on my instrumented engine rig. Glad to do so for anyone who fears their pulley is faulty. John 2 Link to comment Share on other sites More sharing options...
PeteH Posted December 25, 2022 Report Share Posted December 25, 2022 John, Did ALL the 6`s have damper pulleys? or just the later one`s?. I don`t recolect SWMBO`s 2L 6, (steel Fan) being so fitted?. There was I believe, a lengthy discoures on the "damper" subject, Here or in Courier?. a few years back?. Pete Link to comment Share on other sites More sharing options...
NonMember Posted December 25, 2022 Report Share Posted December 25, 2022 My very early 2L Vitesse has a damper. I think they all did. Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 25, 2022 Report Share Posted December 25, 2022 all the six's have a metalastic bonded damper ring (with the timing degrees ) the only problem is the bonding can fail and the ring and its timing marks all move around had this on my 1600 way back and JohnD has a damper harmonics testing rig to prove them ok or failed on mine you could rotate the ring by hand makes TDC quite entertaining Pete Link to comment Share on other sites More sharing options...
johny Posted December 25, 2022 Report Share Posted December 25, 2022 Out of interest, if you cant spin the outer part separately I take it the rubber can still be partially broken so the damping effect is lost? Link to comment Share on other sites More sharing options...
JohnD Posted December 25, 2022 Report Share Posted December 25, 2022 Just as any too old tyre, or elderly rad hose gets stiff and brittle, so may the rubber in the damper. That uses the 'rubberyness' ( hysteresis) of the rubber to absorb vibration energy and damp it out. Stiffened rubber can't do that. A pulley whose outer ring can be turned by hand!!!!! Somewhat of a danger, methinks! It has happened that the outer takes off at speed! About a kilogram of metal at say 4K rpm would be like an armour piercing shell, ricocheting around the engine compartment! As said, ALL sixes had a damper pulley. Today ALL engines have one, in aid of the quest for minimal 'Noise, Vibration and Harshness'. But then it was an engineering and engine design decision. I had an article the Courier on Torsional Vibration a couple of years ago, QV. John Link to comment Share on other sites More sharing options...
johny Posted December 25, 2022 Report Share Posted December 25, 2022 My mk1 Vitesse 2L could certainly be smoother but are new pulleys available? Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 25, 2022 Report Share Posted December 25, 2022 early pulley 133244 seems rare used on many 1600 thro to 2500 later with 3/8 belt Vee is Pulley & Damper Assembly - 3/8 inch Groove - 214479 (rimmerbros.com) if you have deep pockets Pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 25, 2022 Report Share Posted December 25, 2022 54 minutes ago, johny said: 2L could certainly be smoother most 6s seem to have a bit of a rythmical vibro period mid range Knowing your inputs here Im sure your tappets and timing are spot on one thing that seems to complement this is worn timming chains which get longer as the links wear make the valve timing a bit late but with christmas theres little else to dream about ive tried me socks on and just wait the crown to cook through the joy of not having turkey sandwiches in the lunch box is .....imeasureable !!! regards Pete Link to comment Share on other sites More sharing options...
JohnD Posted December 25, 2022 Report Share Posted December 25, 2022 A straight six cylinder engine - any straight six - has the smoothest design of any other. Within reason - straight twelve, anyone? Others suffer from various moments as their reciprocating parts rotate, but in a six they all cancel out. Primary and secondary balance is important, but here we speak of torsional vibration, that can potentially damage to the crankshaft. Link to comment Share on other sites More sharing options...
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