Correct valve clearance m20. Solution to ticking e30

[nickmcc92]

When I first bought the car i set both exhaust/intake: .010" (.25mm) like the manual says, but my car would still tick.

So, i read that it was the injectors that ticked. So, I swapped in some new m50 injectors [thanks to MEPEH] and my e30 still ticked!

Newbie TIPS:
-make sure lobe for the valve you're adjusting is pointing down. (Doesnt have to be in firing order.
-you can remove spark plugs so you can turn crankshaft easier.
-started left-right. If cam lobe was pointing up, I turned the crankshaft 90 degrees two times so it would be pointing down. Then on to the exhaust valve.

So correct valve clearance for both intake/exhaust :
-.008" for a quiet engine, but a loss of performance (minor)
-.010" for ticking but way better performance.



UPDATE: I'm settling at .009" exhaust/ .008" intake. Still quiet, and some of the performance is back.

[nickmcc92]

Such a good looking car is not supposed to tick when it comes out of the factory.
So a ticking m20 is not necessarily a happy m20 :)

[jlevie]

I don't remember what the number is, but if you adjust the valves between the rocker and cam the clearance is different.

If the valve tick when adjusted to factory spec's (at the valve stem). The valve guides are probably worn or your adjustment procedure is not right. The best way to accurately set the valves is to use a spring tool to move the eccentrics.

The valves will tick on a cold engine but if correctly adjusted and if the head is in good condition they should be almost totally silent once the engine is at normal temperature.

[nickmcc92]

Thanks for the reply. Any information why I have to set to .008" helps.
Yeah when they were adjusted to spec (.010") my valves would tick, but at times it would be silent. It was very rare though.

[digger]

if putting the feeler between the cam and rocker you need to use a different feeler gauge (smaller one) since the rocker ratio is not 1:1

[jeffnhiscars]

if putting the feeler between the cam and rocker you need to use a different feeler gauge (smaller one) since the rocker ratio is not 1:1

This ^

If you adjust them too tight they are quiet cause they dont close...until they burn. Then its a whole other story.

[digger]

This ^

If you adjust them too tight they are quiet cause they dont close...until they burn. Then its a whole other story.

if the same feeler is used things will end up excessively loose at the valve tip

[nickmcc92]

I don't necessarily know what you mean by a smaller feeler gauge. I would think the clearance would be the same on both sides

[whodwho]

It will not be the same because of the rocker ratio.

There can be excessive clearance after adjusting with a feeler gauge from having a dish in the end of the valve stem. In that case you might need a dial indicator or adjust from the cam end but you will need to adjust for the rocker ratio.

[nickmcc92]

I understand now. Hope this helps others.
I kinda miss that .002" difference in power though.
Plan to adjust to .009" and will post results.

[TobyB]

-put the feeler gauge in between the camshaft and rocker arms.

that's a great way to score the cam lobes... not that it matters much on the backside, I guess.

Using math, with a 1.4:1 ratio for the rocker, .015 /1.4 = .0107 on the cam side, so if you lashed to .008 on the cam, that's .011 at the rocker... that won't burn valves, but if it's quiet, off you go.

One thing I found that helped a lot- new eccentrics. The old ones get flats worn in
them, and as you tighten 'em a bit, then the very end of that flat's hitting the valve
stem. Apparently, that's noisy. Also, messes up the geometry just a bit.
Found that out by accident.

t

[nickmcc92]

Wow, thanks for clearing that up Toby.

[nickmcc92]

Just changed the valves to .009" on the eccentric side and the car is perfect.
Now it's starting to feel and sound like a BMW.

[AndrewBird]

The only way there would be a difference in power after adjusting valve lash is if they were WAY off. I think the power difference was in your head.

[jeffnhiscars]

The only way there would be a difference in power after adjusting valve lash is if they wetter WAY off. I think the power difference was in your head.

I know we are discussing an M20 but when I took my M10 from .010 to .008 it let it pull right to redline instead of falling off steeply at about 4000rpms. I also recall Jlevie posting that with a fresh M20 head (as iin guides etc) you could take it down to .006 (perhaps that was just the intakes) and get better results so there may be something to this.