daverclasper Posted May 10, 2018 Report Share Posted May 10, 2018 Hi. On a MG site it said that an engine had valve clearance specified at 15 tho" cold. A later specification was 13 tho" hot for the same engine. So I assume heat expansion of valve train at the rocker/valve is about 2 tho". I'm wondering if I can relate this to my Triumph. as I have rocker pad indents on some rockers and can't get a good reading with feelers. I have been setting a good rocker with feelers and relating the feel of this by hand to adjust the other rockers (someone on club Triumph recommended this technique). My main concern with this, is I could be setting them a bit tight and valves could burn (I guess secondery to that the valve would be opening a bit earlier/closing later. So, would the MG info imply that that as long as there at least a 2 tho+ gap, then the valves will be closing fully on an MG and therefore maybe something similar on a Triumph?. Or maybe I'm way off, with this theory?. Any help great please. Thanks Dave Link to comment Share on other sites More sharing options...
JohnD Posted May 10, 2018 Report Share Posted May 10, 2018 If you must persist with indented rockers, then an SPQR, or ClickFit device, will adjust them correctly. Certainly better than guessing. Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 10, 2018 Report Share Posted May 10, 2018 If you get sleepless over a hot to cold tolerance set it cold then measure what you get when hot Johns right a guess is very variable the devices he's mention use the pitch of the tappet thread to measure the gap from being closed to whatever the spec is by a known rotaion of the screw Pete Link to comment Share on other sites More sharing options...
daverclasper Posted May 10, 2018 Author Report Share Posted May 10, 2018 Thanks a lot. Have just bought 18 second hand rockers for a fiver with a view to dressing some of the better ones (I seem to remember your not keen on that John!). Then hopefully I won't be persisting for ever. Will certainly bear the above devices in mind (I don't suppose counting amount of adjustment turns for 10 thou", then doing this from closed gap would work, guess not as folk would do it). Cheers, Dave Link to comment Share on other sites More sharing options...
JohnD Posted May 10, 2018 Report Share Posted May 10, 2018 Yes, it would! If you know the pitch of the adjuster screw on the rocker, which is 24 TPI (Threads Per Inch), so 1000/24 thou per full turn, or 41.7. You want 15 thou, so 41.7/15 th of a turn or 0.36, a third, give-or-take. The ClickAjust (not ClickFit) provides detents that click, 30 to a turn, so 10 clicks. Simples! John Link to comment Share on other sites More sharing options...
daverclasper Posted May 10, 2018 Author Report Share Posted May 10, 2018 (edited) Thanks John. I thought I'd would go to the bottom of the class for that one Just one thing. Haynes book showing valve to rocker at 10 thou for Vitesse?. Cheers, Dave Edited May 10, 2018 by daverclasper Link to comment Share on other sites More sharing options...
JohnD Posted May 10, 2018 Report Share Posted May 10, 2018 If I may, do the maths! But OOOPS! I did the maths wrong last time! And it still gave a near right answer! The calculation should be 15/41.7, which as it happens = 0.3597, or 0.36 of a turn! For 10 thou it's 10/41.7 = 0.24 of a turn, a quarter, or 7.5 clicks (30/4). You choose, 7 or 8, because one click will be 1.4thou. John Link to comment Share on other sites More sharing options...
daverclasper Posted May 10, 2018 Author Report Share Posted May 10, 2018 Great. Thanks for that. Out of interest I will note how much of a turn it takes to close the gaps and see what my guessing is like. Dave Link to comment Share on other sites More sharing options...
daverclasper Posted May 13, 2018 Author Report Share Posted May 13, 2018 Have adjusted by above method, though to get 10 thou, it only required backing the adjusting screws 30 degree turns (rather than 45 degrees/ quarter turn)?. I confirmed this on a number of valves. Cheers, Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 13, 2018 Report Share Posted May 13, 2018 Think we have said if fettling the pads leave the wear pad just remove the sides Rockers are generally flame or induction hardened the pads are pretty tough but easily workable to improve feel entry Pete Link to comment Share on other sites More sharing options...
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