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Post by tommydp on Jan 5, 2017 15:46:25 GMT
Never owned an automatic, but I suppose it should be the same if it's in neutral.
The engine should turn easily with plugs out. I grab a blade on the radiator fan with my left hand and the alternator fan and pulley with the right hand, pressing down the fan belt with my right hand thumb to apply pressure to the belt. It should then be simple to turn the engine while watching the valves. Never done it another way, and never had problems. With that:-)
Tommy
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Post by paddymk2 on Jan 6, 2017 2:14:29 GMT
Hi David,
Probably its just me.
When you said,
There are several methods but the easiest I find is the rule of 9. When valve 1 is fully open, check and adjust no 8 clearance (1+8 =9), valve 2 fully open check and adjust no 7 (2+7=9) etc. No 1 valve is closest to the radiator. Some like to check the gaps in pairs but if you are unfamiliar then what I suggest should help avoid any confusion.
How critical is it to be sure the valve is fully open - like it moves all the way down but then how sure to you have to be that you're not a few degrees off. Is that what the check is for?
Do I need to figure out where TDC is etc. with this method.
Paddy
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Post by dave1800 on Jan 6, 2017 2:36:15 GMT
It is not very critical but the valve should be fully open for a number of degrees. After setting using this method, I recommend checking each tappet again by rotating the engine a fully cycle (2 turns) with the feeler gauge still inserted. If you find it loose at any point then tighten it to 0.015". Sometimes you can find there is 0.001 - 0.002 that can be taken up, but remember too tight is definitely bad. This also acts as a check to ensure you had the valve fully open.
It would be difficult to ascertain TDC accurately using this method as you would need to know what camshaft is fitted and take into account any slack in the timing chain. It is usual to determine TDC by other means and once confirmed use it to ensure the correct valve timing.
Unless the camshaft has been replaced or the timing chain replaced/removed/changed if the engine was running smoothly then it is unlikely that the valve timing is out.
Tommy is our resident expert on valve timing.
When you have set the tappets, I would suggest checking the ignition timing is a good idea as this can affect the running and engine life. After that, the carb (not the first thing that many try and adjust).
David
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Post by paddymk2 on Jan 12, 2017 12:55:04 GMT
Hi Dave,
I got the tappets sorted at the weekend. Its hard to say if they sound any quieter than before - but at least they're all the same and clear.
Thanks for the tips on what to do next.
Paddy
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Post by dave1800 on Jan 13, 2017 12:13:29 GMT
Hi Paddy
At least you know they are set correctly. Unfortunately these engines are well known for sounding tappety and while there are various techniques for determining which valve train(s) are involved the solution is not that straight forward so most owners grow to live with it.
keep in touch
regards
David
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wolseley1800
Member
Posts: 127
Attribute: The Voice of Doom!
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Post by wolseley1800 on Jan 13, 2017 22:11:20 GMT
My Dad, (ex REME, BMC trained etc), always said to panic if you can not hear the tappets on the 'A' or 'B' series engine. That is unles it was "blue printed".
I use the auto click adjuster, so much better as it allows you to allow for play.
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Post by Penguin45 on Jan 14, 2017 0:47:10 GMT
Ah - is that the same thing as "If it's not leaking oil, there isn't any left"?
P45.
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Post by tommydp on Jan 18, 2017 23:00:02 GMT
Right, just wrote a massive reply here. Disappeared as I was finished and ready to post it...arghhhh...
Short version:
Checked all valve clerances for a full cycle, as suggested by Dave.
Set to 0.015 with a slight drag by the rule of nine first. Then felt for increase in clearance through the cycle. From the point of adjusting (rule of nine) the clearance remains unchanged until the valve opens. A while after it is closed the clearance increases, on all valves. Two are extreme. The clearance seems to be largest at the point where the "opposite valve" by the rule of nine is just about to open.
Here are the clearances, when the opposite valve (rule of nine) is just about to open. They were ll set to 0.015 when the opposite valve was fully open first. The clearance at tdc firing in parenthesis:
Valve 1: 0.020 (0.015)
Valve 2: 0.016 (0.016)
Valve 3: 0.018 (0.018)
Valve 4: 0.016 (0.016)
Valve 5: 0.017 (0.015)
Valve 6: 0.020 (0.020)
Valve 7: 0.016 (0.015)
Valve 8: 0.016 (0.015)
So, what does this mean, and should one worry?
Tommy
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wolseley1800
Member
Posts: 127
Attribute: The Voice of Doom!
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Post by wolseley1800 on Jan 18, 2017 23:28:46 GMT
There are many reasons for wrong readings
Amount of oil on gauges
Dirt in gauges
The variation in the calibration of your hand
Worn parts
ect ect ect .......
If you use a spanner and screwdriver make sure you are pressing down whilst you adjust the gap, this helps to take some of the play out of the system.
As I mentioned before, get an auto adjuster - they do help
I personally wouldn't worry
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Post by dave1800 on Jan 19, 2017 2:04:40 GMT
Tommy, as I mentioned you can often find another 1-2 thou by rotating the engine for the full 360 degrees after setting the tappets using the rule of 9. I agree with wolseley 1800's assessment and recommend using the auto audjuster to take up wear. However I think you need to have a look at the 0.020" for valve no 6 as this looks excessive. Are the shims under the centre rocker pedestals in place to help prevent the shaft from turning and wearing for example.
One thing you could do is to check the gap with the engine running to see if it something only apparent when stationary (eg some flexing of the rocker shaft). (Note although this was common practice when I was growing up, I could not recommend it for novices because of the obvious dangers of trapping clothing, fingers etc). Start the engine with say a 0.015" feeler in place and see if it still feels intermittently loose. Perhaps commence by inserting a 0.005" feeler in no 6 tappet gap to see if it reduces tappet noise. Remember as the engine heats up the gap will close by around 0.002". You could repeat your original check with a hot engine to see if this issue with no 6 still exists.
regards
David
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Post by tommydp on Jan 19, 2017 6:34:52 GMT
The shims are there, and I believe the rocker assembly is fine.
I've tried inserting a thin feeler gauge while the engine runs, and it quiets very when I do it on valve 6. This has more of a knocking sound, while the others have the usual ticking. It still knocks if I tighten the clearance temporarily.
I've got another cam, which doesn't look too bad. Would be interesting to try it, to see if it makes a change.
Tommy
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Post by dave1800 on Jan 19, 2017 11:15:39 GMT
Have you tried pressing down quite hard on the no 6 adjuster as you measure the gap? It sounds as though it may be a damaged tappet, if so it should be changed wthout too much delay.
regards
David
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Post by tommydp on Jan 19, 2017 19:31:05 GMT
Yes, have tried that. The difference in clearance is obvious no matter how I set it.
I have checked the tappets and pushrod, also tried others. Tappet is good, no pitting and pushrod is straight. Clearance is the same if I rotate the pushrod.
Suppose, it just can't be anything else than the cam lobe. I'll try another cam. Perhaps this cam has suffered over tightening of the number 6 valve clearance, as in my exoerience valve number 6 is always noisier than the others.
Tommy
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Post by dave1800 on Jan 20, 2017 13:10:25 GMT
Tommy, it may not be the cam lobe itself but possibly opposite the lobe has not been ground correctly so you are finding an extra 0.005" on rotation if there is an offset. If this is the case, and there seem to be MGB owners suggesting it is not that uncommon, then you could tighten the tappet to give a maximum of 0.015" gap. Certainly with the gap at 0.020" and you hearing hammering rather then tapping this cannot be doing the cam lobe or tappet any good. Your call! EDIT: I have found this comment from Peter Burgess "....Sometimes cams are not ground perfectly and there can be a dip which makes the tappets rattly, if you have a noisy one turn the engine by hand to find the loose spot on that roacker and adjust accordingly...." BurgessDavid |
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