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Tech Forum : m20 valve adjustment - too tight? Issues,,,

- BMW E21 Community
   - Tech Forum
      - m20 valve adjustment - too tight? Issues,,,
g323   Posted Friday, Oct 17th 7:53am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 306
   
California
323i 1982
So I cant figure out how to tell which valve is completely closed. I feel like im not understanding what is going on.

is one valve only completely closed at all times? so i adjust one valve, turn it, adjust another, turn, adjust another?

If this is the case, how can I visualy tell which on is the most closed of all of them?

what I did was this:
I found the most loose valve, or the one that fit the feeler gauge - I then tightened it down on the feeler gauge, then turned it, then looked for the next one that was loose enough to put the gauge in, and tightened it aswell. doing it this way i don't think i got all the valves, and i worry that one might be too tight? is this possible? the thing is, doin it this way i am only tightening the loose valves, not loosening the tight ones - albeit that the problem was loose valves making the thing tick loudly(which has now stoped).

in summary:
- im confused as to how to tell which valve to adjust
- also i want to know if its possible given what i did, that i overtightened a valve??(i didnt tighten anything tighter than what the writeup tricord wrote specified and hte engine was stone cold)
- can overly tightened valves cause overheating?



TJ   Posted Friday, Oct 17th 9:50am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 67

NY, USA
82 528e2i 84 320i/4 80 320i
The way to do it is one cylinder at a time. Look at the rocker arms and cam lobes. If the lobes are pointing down, away from the rocker arms, then those valves are closed.

If the valve clearance is tighter than it should be, then when the engine warms up there may not be any clearance at all and the valve can't close. This can cause a few different problems, not the least of which is the exhaust valves themselves overheating since the heat doesn't get transferred away by making contact with the valve seat.

So if the valve train has quieted but you think you missed some of them you might want to go through again and just stick the .010" gauge in there to make sure none are too tight.

g323   Posted Friday, Oct 17th 6:59pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 307
   
California
323i 1982
but is only one closed at a time? i feel i look at the lobes and i feel a couple are closed(pointed straight down) at each time, and i don't want to loosen the wrong ones...

(thank you btw)

TJ   Posted Saturday, Oct 18th 10:25am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 68

NY, USA
82 528e2i 84 320i/4 80 320i
More than one valve can be closed at the same time. For instance, when piston #1 is at top-dead-center on the compression stroke, both intake and exhaust valves will be closed on cyl #1. Then you can turn the crank 120 degrees and the next cylinder in the firing order (#5) will be at TDC and its valves will be closed, etc.

paul dyer   Posted Saturday, Oct 18th 11:06am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 40

manchester england
1977 rhd 320i/4
If cylinder no 1 is at top dead centre(both rockers on that cylinder are just touching a cam/exhaust comeing off cam and inlet just starting to open)then adjust cylinder 6...if 2 rocking adjust 5..if 3 rocking adjust 4..if 4 rocking adjust 3..5 rocking adjust 2..6 rocking adjust 1(on a six cylinder car)

g323   Posted Saturday, Oct 18th 9:08pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 309
   
California
323i 1982
ooooooooooo,oo

ok, so since the shape of the lobe has a point, i was thinking that that point needed to be pointed 120 degrees away from the rocker, but as long as its pointed more or less down its alright? there is no exact point?


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