E30 Zone

Is it possible to adjust tappets on the M20 engine? Mine are tickey, one in particular

Have a read:

http://www.e30zone.net/e30zonewiki/inde ... M20_engine

Always worth checking your valve clearances but I think you'll find the injectors are the most likely culprit of the noise. Nothing you can really do, will still be noisy after a refurb and no matter what a seller/trader tells you their secondhand ones will be no better.

big mistake most people make is setting the clearance to 010 between the cam and follower which is the only way to do it because the eccentric usually makes a hollow in the tip of the valve stem so its impossible to get an accurate setting using a feeler gauge in this location

BUT!!! when you set using cam to follower clearance the setting should be 006" NOT 010" because the rocker ratio is 1.5:1 so this must be taken into account.

9/10 times set it like this and the ticking goes away

Thanks for all the advice, I set for 020 and they didn't appear much worse than this in the first place (maybe 030). Noise reduced for sure, but could be better. might go for 015 or 010.

Another thing that I read in the Wiki article posted by Grrrrmachine above, thanks! is over heating.
My temperature guage rises at idle, even after changing viscous fan and fitting new water pump.
Is that attributed to valve clearances or something else. I plan to take out the thermostat and drill a hole in it. The car heat up quickly from cold now, but is also difficult to avoid airlocks as the thermostat doesn't allow water around the engine until well warmed.

I'm going to have a second attempt at this tomorrow. As my first attempt made it worse. I think I was a bit generous with how much resistance was left on the feeler gauge.

I did mine to 0.25mm (how does this translate to 020, 015 etc?). I've read a few bits here and there in the past and have got the impression you shouldn't go any smaller with the clearance. What are everyone's thoughts?

If the excentric adjusters are worn (i.e. a flat spot) then the effort of adjusting them is useless as they will just revert back to their original position after a few minutes of driving.

The correct guage to use at the cam/rocker gap is 0.17mm, taking into account the rocker ratio of 1:1.5 as stated by e21jps, this eliminates the error introduced by concaved wear on the valve stems, which in my case was responsible for between 0.020 and 0.035mm of error when measured at the valve stem/excentric.
I have done mine this way (along with new excentrics) and it has quietened down a lot.

There are some strange figures being banded about here.

The valve clearances should measure 0.25mm when cold (a loose sliding fit on the feeler), between the eccentric on the rocker and the tip of the valve. 0.25mm is indeed 0.010", the decimal places and unit of measure are an important factor here. Never set the clearances tighter.

If your valve tips are concave, then you will be fighting a losing battle with regard to valve train noise. Once the constant hammering wears through the hardened outer layer of the vave the wear will just snowball.

The rockers have an theoretical ratio of 1:1.5, as they are 2 cams acting upon each other, so the ratio varies throughout the cycle.

That's a quick dirty representation of the rocker ratio change through the motion of the cam.

However the variation in the rocker ratio is due to the angulation of the rocker and the difference between the cam contact point and the center point of the pad.
(there is a motion at the valve tip that has an effect but it is minimal).

In the case of setting the tappets the cam will contact the pad in the center and the angualtion is effectively the 0 reference point.
So in this case the ratio can be seen as 1.5:1 like it is directly over the nose of the cam.

Thus, 0.006" (0.15mm) will set the tappets accurately if done at the cam with the pad on the BCD.

Is this the kind of thing that a learning hobbyist could have a go at? Mine's tappy and I've tested to see if it's the injectors as per a different thread (get it to 3k then cut the engine and listen if it taps as the engine dies)

I've not done anything like this before but I assume a set of feeler gauges can't cost much..?


EDIT: After reading the wiki page on it, it looks to be simple enough!