daverclasper Posted February 19, 2023 Report Share Posted February 19, 2023 Hi. When doing this, I visually try to determine when the corrosponding valve/s are open fully to set the relevent closed valve gap. Is this ok and accurate enough for the correct gap?, as I assume there is a some leeway anyway with the valve closed, due to the circular heel of the cam turning a bit after closing and then begining to open valve. This is how I've always thought it would work out myself?, though been thinking for ages I should check. Hope this is making sense? Chhers Link to comment Share on other sites More sharing options...
johny Posted February 20, 2023 Report Share Posted February 20, 2023 The Triumph workshop manual says to get the pushrod end of a rocker to its highest point by eye and then turn the crank a full turn (=1/2 cam revolution) so the tappet is on the back of the cam and the rocker clearance can be checked... However this method requires a lot of crank rotation so on a six cylinder most people use the rule of 13 as you have described Dave. Youre right the back of the cam lobe has plenty of track so positioning accuracy doesnt need to be 100%. Link to comment Share on other sites More sharing options...
DJB350Z Posted February 20, 2023 Report Share Posted February 20, 2023 17 minutes ago, johny said: However this method requires a lot of crank rotation so on a six cylinder most people use the rule of 13 as you have described Dave. Youre right the back of the cam lobe has plenty of track so positioning accuracy doesnt need to be 100%. This is how I recently did it. Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted February 20, 2023 Report Share Posted February 20, 2023 Plus 1 for the rule of 13. (Apart from when working on four cylinder engines that is!) Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 20, 2023 Report Share Posted February 20, 2023 or to save turning the engine much get a cyl on its compression stroke( both rockers in balance ) and set both rocker at the same time just follow the firing order then both cams are on their backs Pete Link to comment Share on other sites More sharing options...
Iain T Posted February 20, 2023 Report Share Posted February 20, 2023 I used the EOIC (exhaust opening inlet closing) method. Did involve a lot of hand cranking. Iain Link to comment Share on other sites More sharing options...
cliff.b Posted February 21, 2023 Report Share Posted February 21, 2023 For the 4 cylinder engine, the Haynes manual appears to follow the rule of 9 with the sequence suggested giving the least possible crank turning. Think it's only 2 complete turns. I assume their manuals for 6 cylinder cars would have something similar. Link to comment Share on other sites More sharing options...
JohnD Posted February 21, 2023 Report Share Posted February 21, 2023 Daver asked for a visual method. The Rules of 13 (or 9) require a bit of mental arithmetic, which I'm not good at, so instead I use the "Mirror" method. Imagine there is a mirror between the two central bores, six or four. Turn the engine until two valves - doesn't matter which - are fully open. Then go to the valves that they would be if they were reflected in the mirror. EG, as above, No.8 fully open - adjust No.1, or No.5 open adjust No.4. As you can see, this parallels the Rules. And one tip. To be sure that you do them all, making paper notes will get messy! I keep a tub of Vaseline handy, and put a dollop on each rocker adjusting screw as I complete it. Then I can see which valves I have done, and know when I have completed the cycle. Vaseline, because it dissolves quickly in engine oil, when a dab of grease might take longer and block an oilway. John Link to comment Share on other sites More sharing options...
cliff.b Posted February 21, 2023 Report Share Posted February 21, 2023 21 minutes ago, JohnD said: Daver asked for a visual method. The Rules of 13 (or 9) require a bit of mental arithmetic, which I'm not good at, so instead I use the "Mirror" method. Imagine there is a mirror between the two central bores, six or four. Turn the engine until two valves - doesn't matter which - are fully open. Then go to the valves that they would be if they were reflected in the mirror. EG, as above, No.8 fully open - adjust No.1, or No.5 open adjust No.4. As you can see, this parallels the Rules. And one tip. To be sure that you do them all, making paper notes will get messy! I keep a tub of Vaseline handy, and put a dollop on each rocker adjusting screw as I complete it. Then I can see which valves I have done, and know when I have completed the cycle. Vaseline, because it dissolves quickly in engine oil, when a dab of grease might take longer and block an oilway. John Yes, guess it achieves the same thing. I just find it useful to have the optimal sequence to minimise crank turning written down in front of me. And as long as I can remember which one I am currently adjusting I can just carry on to the next one until I get to the bottom of the list 👍 Link to comment Share on other sites More sharing options...
JohnD Posted February 21, 2023 Report Share Posted February 21, 2023 Ah, Cliff! But what if you miss a line? That has been known! JOhn Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 21, 2023 Report Share Posted February 21, 2023 or a dab of tipex on the ones you have adjusted a small dot is all you need when the dot to dot is complete youre done !!! or any marker pen together with the handy jotter and a pencil to record your work Pete Link to comment Share on other sites More sharing options...
cliff.b Posted February 21, 2023 Report Share Posted February 21, 2023 2 hours ago, JohnD said: Ah, Cliff! But what if you miss a line? That has been known! JOhn I suppose there is more chance of that with a six lol I wonder how they got on with adjusting the tappets on a Merlin engine, orca 28 cylinder Pratt & Witney. I was going to say the 16 cylinder Napier Sabre engine, as fitted to Hawker Typhoons, but then remembered they wouldn't have tappets 🤔 Link to comment Share on other sites More sharing options...
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