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Valve adjustment


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You can certainly check the clearances quite easily using a set of feeler gauges.

However, having checked them, if they need adjusting its quite an involved operation involving removal of the cam belt and camshaft housings

Then there is an iterative process of measuring the existing shims and obtaining thicker/thinner ones depending on the gap

Unlikely to wear that much in 10000 miles

John

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There will be a slight tap tap but nothing loud...have you thought what oil your using may have an effect on it? And are you certain there isnt a crack or hole in the exhaust manifold...this can sound like a clicking...a tiny pin hole in mine when I first had the car did this..

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not to hijack your thread...

I too have a clinking sound from the cam area.  removing the cam covers and all accessory belts and rotating engine slowly, it seems to be in the exhaust valve system.  there is a loud clink that can be felt with hand on engine block as cam lobe just about leaves tappet on 3 of the cylinders.  it has been getting progressively louder at idle, but higher rpms seems to quiet it.  I don't see the cam lose contact with the tappet (my eyes aren't great anymore though)  but it seems like a valve hangs open then closes the gap between the tappet and cam suddenly, unlikely as that is.  I don't see any broken inner springs with the cam towers removed.  cams don't make noise spinning in the removed towers, but they are not under load

I was curious about my current shims.  seems they are on the thin side but still in the range of Lotus replacement thickness.

car has 68k.  is this close to what others have measured?

 

 

shim thickness

 

intake .092 .089 .091 .090 .088 .084 .084 .090

 

exhaust .092 .092 .095 .094 .093 .093 .092 .098

Edited by ragingfool35

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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As you say, all of those shims are within the normal range.

However, it's the gap between the cam lobe and the top of the cam bucket that is the important measurement.

This needs to be measured cold with the cam towers torqued down. The gaps are 5-7 thou for one and 10-12 thou for the other. It's in the manual which I haven't got handy so I'll almost certainly say the wrong way round if I guess.

There are several threads on here covering shim checking, my tip would be to buy a digital vernier gauge or micrometer and a good set of feeler gauges. Then use a spreadsheet, again it's available on here, to help identify which shims you need to swap

John

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i think those values are reversed?  gaps were all at the low end.  I had made a spreadsheet with target value at the high end.  thanks though :) I have a lead on the source of the noise.  will report back shortly

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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Guy

I found the problem.  my pulley has a loose fit on the intake cam.  the belt is rotating the cam compressing the valve springs until other side of lobe where springs close the valve.  here the springs try to rotate the cam in the opposite direction.  the small amount of play causes my loud clink, at high rpm, there isn't time for this to happen.

try tightening your cam pulley retaining bolts and see if it makes a difference.

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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In my previous post the clearances for the inlet / exhaust valves were reversed. The attached calculation sheet is correct. So below are the correct numbers:

 

Inlet valves: 0.005" - 0.007"

Exhaust valves: 0.010" - 0.012"

 

 

Just fill in the yellow fields after unzipping.

Valve Clearance.zip

 

(maybe a moderator can remove the wrong post in order to avoid confusion)

Esprit Freak

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Inlet valves: 0.005" - 0.007"

Exhaust valves: 0.010" - 0.012"

 

This isn't difficult to remember, the larger gap is always for the exhaust valve as this gets much hotter than the inlet valve & so expands a lot more requiring far more clearance to stop it constantly being in contact with the cam lobe & so never fully closing.  :thumbsup:

Cheers,

John W

http://jonwatkins.co.uk

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I'm sorry I am in the middle of building a s*****d  gazebo. I have had no time to get my car.

 

To be honest I'm nervous about checking the "cam pulley retaining bolts".

 

If the pulley was loose, wouldn't you notice it by jiggling  it.  

 

 

Guy

Edited by Guy W Johnson
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