bigmalcy Posted October 9, 2013 Report Share Posted October 9, 2013 Hi guys A quick question on setting valve clearances on a four pot running standard cams etc. I went through this process following initial start up of our rebuilt engine, but I think I may not have done it properly: I measured the clearances (when cold) for both the inlet and exhaust valves on each cylinder when that cylinder was at TDC. I thought this would be ok given that both valves would be well and truly closed at this point of their cycle. I now note (having RTFI’d) that you are supposed to carry out this adjustment when the cam lobe for the valve you are adjusting is exactly opposite (180deg off) the tappet (rule of 8’s and all that). The question is – do i need to redo the clearances? According to my basic geometry calcs, each of my cam lobes would have been approx 135 degrees off the tappet instead of 180 degrees. I am interested to know what the geometry of the cams are – for what portion of their circumference are they round? Finally – I also assume that doing it the way i did would only (at worst) result in having greater clearance than specified and hence poor running rather than any valve seat burning issues. Thanks in advance for your help. Malcolm Quote Link to post Share on other sites
Motorsport Mickey Posted October 9, 2013 Report Share Posted October 9, 2013 Rule of 9, no don't run it if you are bothered enough enough to have a TR, do it again...correctly. Mick Richards Quote Link to post Share on other sites
RogerH Posted October 9, 2013 Report Share Posted October 9, 2013 Hi Malcolm, your method would result in slightly larger gaps - it would sound a bit clattery or that you had a high performance cam insitu, which you haven't. Micks suggestion of the rule of 9 is what most people follow - get #1 valve compressed as far as it will go then adjust #8 You will see other valve starting to compress do them next - #6 compressed, adjust #3 and so on. I suppose a 6 cylinder would use a rule of 13 but not sure. Roger Quote Link to post Share on other sites
peejay4A Posted October 9, 2013 Report Share Posted October 9, 2013 Another way of doing it is, for each cylinder, when the inlet valve starts to close adjust the exhaust gap. When the exhaust begins to open adjust the inlet gap. Quote Link to post Share on other sites
TR Mitch Posted October 9, 2013 Report Share Posted October 9, 2013 Good tips, I'm about to do mine since a couple rattle a bit. Will find out whether there is any valve seat recession too. Will check if the 13 rule works on a six pot and report back. Quote Link to post Share on other sites
bigmalcy Posted October 9, 2013 Author Report Share Posted October 9, 2013 Thanks fellas - i'll re-do em this weekend before going for a drive... Quote Link to post Share on other sites
PJM Posted October 9, 2013 Report Share Posted October 9, 2013 Rule of 13 is correct for a 6 Quote Link to post Share on other sites
Ian Vincent Posted October 10, 2013 Report Share Posted October 10, 2013 I'm sure that I have read about another rule 9. Something along the lines of when 1 and 8 for example are both at their mid point, you should adjust one of the others, but I can't remember which one it is. Also, if you are having difficulty in tracking down a noisy tappet, buy a strip of feeler gauge (2 thou?) from an engineering supplier. Run. the engine with the valve cover removed and progressively slide the strip between the rocker and the valve stem. When you come to the one with excessive clearance, the noise will stop. It knackers the strip but they are only pence to buy. Rgds Ian Quote Link to post Share on other sites
littlejim Posted October 10, 2013 Report Share Posted October 10, 2013 As you are going to do them again take them off and retorque the head bolts. I did a head gasket in by leaving the retorque a bit too long. (on a 4 cylinder donk.) Quote Link to post Share on other sites
Motorsport Mickey Posted October 10, 2013 Report Share Posted October 10, 2013 Maybe a couple of hundred miles before retorquing the head, got to get the engine through a few cycles first. Mick Richards Quote Link to post Share on other sites
john.r.davies Posted October 10, 2013 Report Share Posted October 10, 2013 I'm sure that I have read about another rule 9. Something along the lines of when 1 and 8 for example are both at their mid point, you should adjust one of the others, but I can't remember which one it is. Rgds Ian When rule of 9/13 is so simple, trying to guess the midpoint sounds much more difficult! If you have a more visual than mathematical mind, then imagine that the engine is divided in two along the midline, between bores 2 & 3 (4cyl) or 3 &4(6cyl), by a mirror. Then when a valve is fully down, adjjust its 'mirror image' - this is the same as the "Rules". And I like your shim idea! John Quote Link to post Share on other sites
Motorsport Mickey Posted October 10, 2013 Report Share Posted October 10, 2013 I'm sure that I have read about another rule 9. Something along the lines of when 1 and 8 for example are both at their mid point, you should adjust one of the others, but I can't remember which one it is. Also, if you are having difficulty in tracking down a noisy tappet, buy a strip of feeler gauge (2 thou?) from an engineering supplier. Run. the engine with the valve cover removed and progressively slide the strip between the rocker and the valve stem. When you come to the one with excessive clearance, the noise will stop. It knackers the strip but they are only pence to buy. Rgds Ian Yeah, just don't wear a white shirt when doing it, lol. Mick Richards Quote Link to post Share on other sites
stillp Posted October 10, 2013 Report Share Posted October 10, 2013 I can never understand why this rule of 9 business is supposed to make the job easier. Why is it easier to find a valve that's fully open then use the rule to find which one to set rather than just setting a valve that's fully closed? Quote Link to post Share on other sites
AlanT Posted October 10, 2013 Report Share Posted October 10, 2013 These days an engineers clock-gauge and magnetic stand can be bought for a few pounds. Either good second-hand Japanese or new Indian manufacture. Either will do. Then you can watch the valve position and find the place you want to set it. Then clock the rocker and set any gap you fancy. You can check shaft wear while you are about it. Oh and you can set the OD solenoid properly too. http://www.ebay.co.uk/itm/MITUTOYO-MAGNETIC-STAND-AND-DIAL-GAUGE-0005-125-NO-2507-7010-B-LATHE-TOOL-/151136049658?pt=UK_Measuring_Tools_Levels&hash=item23306919fa Quote Link to post Share on other sites
peejay4A Posted October 10, 2013 Report Share Posted October 10, 2013 I can never understand why this rule of 9 business is supposed to make the job easier. Why is it easier to find a valve that's fully open then use the rule to find which one to set rather than just setting a valve that's fully closed? Ah but how do you know it's fully closed and the follower is on the heel of the cam? The rule tells you that. Incidentally the 9 or 13 rule isn't universal but is OK for the TR engines. Quote Link to post Share on other sites
stillp Posted October 11, 2013 Report Share Posted October 11, 2013 Ah but how do you know it's fully closed and the follower is on the heel of the cam? The rule tells you that. Incidentally the 9 or 13 rule isn't universal but is OK for the TR engines. How do you know when it's fully open and the follower is in the tip of the cam? You still have to watch what the rocker is doing as you turn the engine. Quote Link to post Share on other sites
peejay4A Posted October 11, 2013 Report Share Posted October 11, 2013 (edited) Yes, it's easy to see when a valve is fully open because the cam lobe is pointy. It looks as though I didn't understand your question. How do you do yours? Edited October 11, 2013 by peejay4A Quote Link to post Share on other sites
stillp Posted October 12, 2013 Report Share Posted October 12, 2013 I turn the engine till the rocker is as high as it'll go, keeping a bit of tension on the rocker. Seems to work fine. Quote Link to post Share on other sites
peejay4A Posted October 12, 2013 Report Share Posted October 12, 2013 Sorry, I don't follow. By high as it will go, do you mean the valve is fully open? If so, which do you then adjust? Quote Link to post Share on other sites
Guest ntc Posted October 13, 2013 Report Share Posted October 13, 2013 Another way of doing it is, for each cylinder, when the inlet valve starts to close adjust the exhaust gap. When the exhaust begins to open adjust the inlet gap. Pete That is incorrect chap Quote Link to post Share on other sites
Rob Salisbury Posted October 13, 2013 Report Share Posted October 13, 2013 Pete That is incorrect chap Yep, Neil's right, each lobe of the cam has a clearance ramp, each tappet must be on the base circle of the lobe when you adjust each valve, rule of 9 gets you there. Cheers Rob Quote Link to post Share on other sites
peejay4A Posted October 13, 2013 Report Share Posted October 13, 2013 (edited) It's Macys garage universal advice if rule of 9 doesn't apply. Edited October 13, 2013 by peejay4A Quote Link to post Share on other sites
Guest ntc Posted October 13, 2013 Report Share Posted October 13, 2013 That's there view Pete as Alan T I use a dial gauge on build to check the cam. Quote Link to post Share on other sites
peejay4A Posted October 13, 2013 Report Share Posted October 13, 2013 Here's their explanation. http://www.macysgarage.com/myweb6/valve_adjustment.htm I experimented with this first using rule of 9 then Macy's method. Using Macys I had to close a few up a little more which tells me either I ballsed it up first time or their method is better at finding the base circle. So what's the problem with Macy's then? Quote Link to post Share on other sites
AlanT Posted October 13, 2013 Report Share Posted October 13, 2013 The problem with anything based on feeler gauges is that with old engines you have wear. Typically the rocker face is not smooth and the feeler underestimates the real gap. The rockers tip about a bit on the shaft. You see all this with a clock gauge. Quote Link to post Share on other sites
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