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MG TD TF 1500 - Valve Clearance - This Way
|My neighbor, who is a pretty good mechanic, helped me set the valve lash last night. While he doesn't disagree with the "rule of nines" he did it "his way." Basically he rotated the crank until #1 piston was fully UP. He wiggled the crank to ensure no additional movement of the piston and intake and exhaust valves to ensure the piston was at the top. This was confirmed visually through the spark plug hole. He did all the pistons this way 1-4. Is there anything wrong, or any downsides with doing it this way?
|Oops, he DID set them in the firing order - sorry.
|Even though the valve should be closed a TDC one of the cams may have started its lift and the gap will be closing. Best to do it the rule of 9 way
|Yes, Jan. But he confirms that both valves are closed on that cylinder, and on the compression stroke, by moving the crank a bit more and if the rocker moves he backs it off to the point that the rocker did not move. To me that's the same as watching the rocker end stop moving (wrench or no whench attched as a visual aid) using the rule of nines. He also removes the disributor cap and verifies the compression stroke by the rotor position and the timing marks, and visually checks the piston not moving thru the spark plug hole. I think it's more work his way, but I was curious if there was a problem by not using the rule of nines.
|L Karpman, your description of what he goes through to use his method makes me wonder why does he do it that way. The rule of nines is so simple why throw in all of the other complications? When you use the rule of nines the valve you are checking is on the smallest diameter of the came lobe and you have some leeway either way and still get an accurate reading. Have your friend watch John Twist's video and he'll understand why it is the best method.
|Tim. He's watched John Twist's video. He doesn't disagree with the rule of nines. In his words he's "meticulous" and prefers his own method. As long as it works and is accurate, it's fine with me. I'm just wondering if his way, no matter how complex, gets the job done without any downside. Are you saying his way doesn't work or is inaccurate?
When I grew up,1940's, I was shown how to adjust lash by my two uncles who were mechanics.
Now this would not due on a fresh rebuild.
The engine was running at idle.
The valve cover was removed.
The proper feeler gauge was inserted.
That might have taken some effort.
The lash screw adjusted until you could just move the gauge.
Nut locked making sure the setting did not change.
Sequence did not matter.
|I have a hard time seeing how you keep the box end wrench on the lock nut and a screw driver on the adjustment screw while the rocker is hopping up and down even at an idle.
|John Quilter (TD8986)
|Jim B, my father and his contemporaries always adjusted the valves on a running (American car). It was effective but messy, oil everywhere. Adjusting the valves on a hydraulic valve lifter engine while the engine was running was the only way to ensure they were adjusted properly. You can certainly adjust the valves on a T Series engine while it is running. But why anyone would want to do so is beyond me. As long as the engine is hot you will get accurate setting on a non running engine.
|L karpman, the problem with your buddies method is that without using a dial indicator you can't really be sure the valves are all the way up. With the rule of nines when, let's say, the number 5 (from the front) valve is open you have a pretty large space on the cam where there is no lift under valve lifer for #4 (4+5=9). In other words the #5 valve doesn't have to be in exactly the fully open position to get an accurate adjustment on valve # 4. Your buddies method is less accurate and more time consuming. look at John Twist's video at the 3:05 mark for a good explanation.
|John, I did it as a kid and it was difficult. Don't forget that in addition to the screw driver and box end wrench you also had to have the feeler gauge in hand while adjusting the valves and getting splashed with hot oil on a running engine. As I said, why anyone would want or need to do it on a running T Series engine is beyond me.
|Tim. Here's my buddy's reply.
"You cant get any lower on the cam than the valves than being on the compression stroke. There is no space on the camshaft that is lower than the compression stroke.
As for the video at 3:05, I here what John says but I would hardly call it an "expanation."
Just to be sure, my buddy said "ok, lets do it again using the rule of nines' and see if the settings are the same."
Guess I'll find out one way or the other.
|L. Karpman, let's cut to the chase here. Why does your friend prefer him valve adjustment methodology over the Rule of 9? What is the advantage of his method?
|Tim. Im not trying to argue. I'm the dummy here trying to learn. I asked a simple question. I stated "how" my friend "preferred" to do it, and if that way was ok. The way he explained to me was that doing it his way gave him 3 visual aids to "ensure" that the piston was at the top of its compression stroke and both intake and exhaust valves were fully closed on that cylinder. The rule of nines gives only one viual aid. You know it's extra work, and I know it's extra work, but it's "his" preferred method. He does not dispute the rule of nines at all, and neither do I.
|IMHO, both will work fine. Verifying TDC would guarantee the lobe at low point but the other pretty close. George
|I agree with George...this strikes me as "6 of 1, 1/2 dozen of another". TDC is TDC on the compression stroke no matter what method you use. Using the "Rule of 9's" may be quicker but no more accurate, at least in my opinion.
|Just as a matter of interest, I have always assumed that as long as the valve was on the base circle of the cam, then measurement of valve clearance would be accurate enough. Does it really make a difference if its not dead centre? From the way John Twist does it on the video I would say he is not particular either.
|Dave, that is the benefit of the rule of 9. Number 5 (for example) does not have to be exactly at TDC to get an accurate reading of the lash on number 4. The rule of 9 is so simple I see absolutely no reason to go through the steps describe by L Karpman. If it is good enough for John Twist, etc. etc. I guess we can add valve clearance methods to the "correct oil" debate folder.
|Exactly, so I'm not sure about the fuss in finding TDC perfectly! I always use the rule of 9.
|Once I've done with the rule of 9's, I start the car and run a feeler gauge through all of them and see if it feels good.
|Keith Yarbrough(TD 1275)
|Using the TDC method, how do you know both tappers are striking their respecting lobes at the base circle? I have never looked to see if one is starting up the ramp at that point....in the end it seems more tedious to find exact TDC than the rule of nine....regards, Tom
|My concern it that the feeler gauge, no matter how narrow, may bridge the indents and wear on the rocker arm thus giving a false reading. But having said that I have yet to invest in a dial indicator to double check the clearances.
|John Quilter (TD8986)
|There are in fact three ways of adjusting valve clearances
#1--rule of nine which most people use
#2--L Karpman's friend's method which has gotten a bit mixed up here being passed along second hand but is performed by--
Get No1 on tdc with the valves rocking--exhaust valve just closing-inlet valve just opening -------adjust clearance of the opposite cyl (No4) at this point. Then work round the firing order
Next up would be No3 rocking and adjust No2
#3--The quickest-easiest method
Get tdc lined up on the pointer
At this point if you have a feel of the rockers there will be four valves with zero clearance and four will have clearance--Adjust the 4 free ones to spec then turn the motor over one full turn to tdc again and then adjust the other four
|Willy, the problem with method number 3 is that when the engine is at top dead center all of the closed valves are not at the same position on the cam lobes. Some are starting to ramp up. The beauty of the rule of nines is that when a valve is open, even if it is not perfectly at its highest peak of the lobe, the corresponding Rule of Nine valve (i.e. 8 and 1, 7 and 2, 6 and 3, etc.) will be fully closed. In other words, the corresponding Rule of Nine closed valve is on the part of the cam lobe that has no lift for several degrees in either direction. Quickest and easiest do not equate to most accurate.
|One more benefit of the rule-of-nine is to follow the sequence shown on page A.18 of the WSM. It provides the minimum turning of the crankshaft to complete the job. Bud
Your statement"Some are starting to ramp up."
There isn't a problem with no3 at all, four followers will be on the base diameter of the camshaft ready to have the valve clearances adjusted and nowhere near the lobes or ramps as suggested
It works and works well----believe me it's quick easy and accurate
|Willy, look at the photo of the cam. Notice that lobe #1 is in the valve fully open position. No other lobe on the camshaft is in the same fully open position. Lobe #3 is slightly off fully open, lobe #5 is half way around and lobe #7 is half way around the other direction (i.e. starting to ramp up). Now look at Lobe #1 in relation to lobe #8 (8+1=9). There is no doubt about the relationship between lobe#1 and lobe#8. Lobe #8 is in the fully open position. Even with lobe #3 being slightly off center of being fully open there is no doubt that lobe#6 is in the fully closed position (3+6=9). The rule of nines is more accurate than your option #3. You can use any form of valve adjustment you wish. But presenting a method as accurate when it is not is not fair to people coming here to learn about maintaining their vehicles. I'm not sure this dead horse deserves another beating. But that's up to you.
First of all, I disagree with your take on my posting and am a bit surprised by your reaction.
I don't need a lecture on the 9 method, we all know that works--
"You can use any form of valve adjustment you wish. But presenting a method as accurate when it is not is not fair to people coming here to learn about maintaining their vehicles. I'm not sure this dead horse deserves another beating. But that's up to you."
This is an accurate method and for you to suggest that I'm leading people astray is a touch offensive
It may be a dead horse to you but it is real and works
I have dragged a camshaft out for a look and photographed it for you to study at your leasure
It's an MGB cam but same applies
First pic is with the camshaft in the suggested position it would be in with no1 on tdc with the valves rocking
You can see lobes 1-2-3-5 are up wards and 4-6-7-8 are well down and the cam follower would well and truely be on the base of the lobe well away from any ramp allowing the valve clearance to be adjusted on these
Second pic is a side view further proving the method works
Over and out
No1 is on the RH side
You can see 1-2-3-5 are up the rest well down
No1 on the left
counting from the left 1-2-3-5 up
4-6-7-8 well down and ready for valve clearance adjustment
|Wily, if you think the side of a cam lobe has as much clearance as the bottom of the cam lobe then I'm wasting my breath on you. IMHO the dead horse is off to the glue factory.
|ha ha ha ha ha---
and -Yes that is exactly what I'm saying
have a measure of that cam you have there
As far as wasting your breath goes--- I'd prefer you explained why it wouldn't work for the benefit of the readers here
I'm more than happy to accept your theory if you can prove it
Are you saying the base circle diameter of the cam isn't equal all around the base--
|Don't quit now folks, this is getting interesting!
As a retired teacher of the subjects Technical Drawing and Engineering Studies I do have an interest in simple cam design but no significant practical experience. When drawing cams for point, flat or roller followers it was always our practice to leave any portion of the cam which was not involved with the rise, dwell or fall of the follower as a part of a circle. This could be seen as support for Willy's method but I would have to admit that it is not a necessary feature that the arc maintains this same radius, and therefore clearance, throughout so Tim could also have a point. I can't immediately see any reason for varying the radius but we really need input from someone who manufactures cams as to what is common practice when grinding them. Then we can all go back to setting our clearances by our preferred method(s).
|C I Twidle
|No malice intended, and in the best of spirits, I will put my money on Willy. I seems logical to me that the valve should not move through the large angle described by this method.
|M R Calvert
But I'm still quite open to an explanation why it wouldn't work on this particular cam when it works on others,
Unless there is something very strange about the shape of the base circle -
I'm not taking sides on this OR expecting anyone else to, I just want to know
|Easy enough to validate willy, set the valve clearances using your methodology and then check using the "9 Method". Interested to hear the outcome.
Unfortunately I havn't a standard xpag cam here to play with----wish I did
It works fine on an B series engine
I had a monster cam in my midget with 320deg duration and it worked ok there as well
I also use it on 2.0litre Cortina/Escort as the rule of nine doesn't work on them at all
It just depends on if the original XPAG cam -
Does it have a weird shaped base circle or no
I think at this stage I might have to go visiting to find out
It's no big deal,I just want to know now
If you would like to have a look at an XPEG cam give me a call on 0407 followed by 122 127.
|M R Calvert
|Never mind the rule of nine or any other method, the most hit and miss part for me is using feeler gauges. If I had all the time in the world I could go back and forth forever trying to get the correct feeler gauge to fit perfectly. I adjust back and forth and in the end say "thats it, close enough", but I am usually dissatisfied. So dump the feeler gauges and attempt to do it with a micrometer, which just has to be better for other reasons too. But not so easy I find with no good flat base to mount a magnetic base on. So now I am thinking what I need is a bolt on platform to make the job easier - I can see a way of doing that. Or do I go the whole hog and fit something rather more sophisticated, such as a rail with the micrometer on a carriage with proper bearings. Anyone done it on an xpag?
|Crikey Dave, that's big
I take it you mean a dial indicator
Maybe you could bolt a piece of flat plate onto there somewhere and use your magnetic base on that like you mention,
Thanks for the offer, I have a friend(Scotty) about 10klm out who would have one, I've secured the required lubricant for a visit, possibly this weekend
Would that be Peter? In which case you must be up north. I am in Hobart which would be inconvenient if you are. Peter knows where I am and has called by my place in the past.
|M R Calvert
|Yes, I mean a dial indicator - without a decent platform I don't see a convenient way to do it.
if you use the GO NO-GO method. Feeler gauges are accurate enough to set the valve clearance. This method requires 2 gauges, The first 1 thou below the required value and the second 1 thou above. To set the gap, you need to start with the smaller gauge, adjust to a slide fit, then try the larger gauge, if this does not fit then you have set the gap correctly. If not then redo.
For example for a gap of 15 thou, get 14 and 16 thou gauges, if the 14 fits and the 16 doesn't then, your gap is somewhere between 14.1 and 15.9. I've been using this method for 50 years.
This method assumes that the rocker pads are not worn.
|John. Yes I agree, that works to some extent, but
I find myself going back and forth more times than I would like. The other issue, as you surmise, is that the rocker pads are usually worn / indented to a greater or lesser extent giving a false reading.
|Peter it is - nice work Sherlock
Once you used to be able to buy go-no go feeler gauges that were actually machined with a step in the feeler strip for each size
Don't know if you can still get them
I have a set somewhere, I'll hunt them out and see if they have a brand name on them
|I've had this one since the sixties. It is stepped as you suggest and is manufactured by "New Britain" USA.
Sorry about the poor quality picture.
I've mostly done my adjusting on a hot, running engine. Avoided a lot of oil spill by cutting the top of an old valve cover. Worked quite well. Don't think I'd want cut up a good cover today though.
|Re Dave Hills pondering a mount for a dial indicator. Some years ago I came across a solution for the 1800 engine in a B from, I think, a North American site. From memory it involved adapting a used rocker shaft to mount by a fabricated bracket to the rocker cover studs and an adapted rocked arm to secure the dial unit. The dial unit was slid fore and aft along the rocker shaft (allowed for by the design of the bracket).
I saved the item but on a previous computer so can't quickly search it out. Can anyone else recall seeing the article of confirm my NA site recall?
Perhaps it was the Chicago Clubland site. An outside chance it may have been the Queensland Club site. Yes, I know, both sides of the Pacific - confusing. Memory is starting to do that to me. Especially, as now, I have a four year old granddaughter spinning a salad dryer in my right ear!!
|Yes, that is correct - Declan Burns sent me that article, and its exactly as you say. Indeed its his idea for taking it a step further. Very possible I think, though a simple first step might be to attach a couple of brackets to the rocker shaft pedestals that can safely be left in place. From there it would be possible to mount anything from a flat platform to take a magnetic base or develop something more sophisticated. Doing things in steps tends to reveal issues as you go.
|Ah Dave, you were on to it. It's something I have recently been thinking about again as my rockers need to be checked as part of a thorough tune up.
This thread was discussed between 18/05/2017 and 02/06/2017
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