Valve Adjustment Advice

[otE30touring]

Hi everyone,

I've just done the valve lash on my M20B20 as I was repainting the valve cover so thought I'd better change the cover gasket and do the valve lash while I was in there.

My engine wasn't particularly loud before (atleast from what I can tell comparing it to other M20's!) and some of the valve clearances were definitely questionnable when I went in there. Anyhow did the adjustment to the 0.25mm when cold per the factory spec. Engine definitely runs much better now - I did a completely cold start and it didn't misfire one bit and settled right down to the cold start high idle before dropping down to the standard idle. The thing is though, I'm not sure if I'm just imagining it but it actually seems louder now. I don't know if I just notice the injector tick more now, and maybe some of the clearances were actually too tight before (it did misfire on cold starts but never after that).

My question is therefore how much noise is too much noise? Has anyone had a similar situation to me before? I should also add that all the valve train looks in good shape with no marks or scores on the camshaft, the rocker arms and eccentrics also seemed good.

I uploaded a quick video here of it idling for an example:


Appreciate any advice, thanks!

[biffer]

That is definately much louder than my car..
Quietened mine down by setting clearences to .15mm 'tween cam-lobe and rocker

[otE30touring]

That is definately much louder than my car..
Quietened mine down by setting clearences to .15mm 'tween cam-lobe and rocker

Thanks for the reply - I went back in later this afternoon and made some more small adjustments on 3 of the rockers which has helped get a bit quieter but it's still noticeably loud. I may have another look again though and see what my clearance is like between the lobe and rocker as you say, maybe I can get it quieter that way.

[biffer]

Apparently the .25mm gap at the valve can be affected by wear to the tops of the valves ,or the eccentrics themselves can develop flat-spots and setting the clearances at the cam-lobes gets round these problems.
Another possibility is the oil spray-bar above rockers is partially blocked. Maybe lift the oil filler-cap whilst engine is idling to check there is plenty of oil sloshing about.Engine may stumble when you lift the cap but this is normal.

[BristolE30]

Although sounds loud on the video, I think this is fairly standard. M20 engine very ticky. Mine was much quieter before I did my clearances, but only because some of them were way too tight. I’d just be happy your getting more power now and a better running engine. Let her tick til the sun goes down...

[otE30touring]

Apparently the .25mm gap at the valve can be affected by wear to the tops of the valves ,or the eccentrics themselves can develop flat-spots and setting the clearances at the cam-lobes gets round these problems.
Another possibility is the oil spray-bar above rockers is partially blocked. Maybe lift the oil filler-cap whilst engine is idling to check there is plenty of oil sloshing about.Engine may stumble when you lift the cap but this is normal.

Yeah the oil spray-bar is an interesting one, that hadn't occurred to me actually, I might give that a look. Everything did seem pretty well oiled up there though I must say.

Thanks for the help!

[otE30touring]

Although sounds loud on the video, I think this is fairly standard. M20 engine very ticky. Mine was much quieter before I did my clearances, but only because some of them were way too tight. I’d just be happy your getting more power now and a better running engine. Let her tick til the sun goes down...

Yeah you see this is the thing, I am wondering if some of them were too tight before, and some of them too loose (there's was a lot of movement on the cylinder 4 rockers when I first took the valve cover off).

Took it out for a drive this afternoon and it felt great to be honest, throttle response felt sharper and revs right up to redline with no issues so I think as you say the main thing is that it runs good now. I might give them another once over in a few weeks to see if I can get it a bit quieter.

Thanks for help!

[Lemon98]

That is louder than mine, I set them earlier this year after I bought the car and wasn't happy with how loud they were so did the whole job again and it was much quieter. The first time mine sounded exactly like yours. When I double checked them they weren't quite right so maybe have another crack at it!!

I'll get a video of mine idling soon and send that for reference.

[otE30touring]

That is louder than mine, I set them earlier this year after I bought the car and wasn't happy with how loud they were so did the whole job again and it was much quieter. The first time mine sounded exactly like yours. When I double checked them they weren't quite right so maybe have another crack at it!!

I'll get a video of mine idling soon and send that for reference.

Ah I'm glad its not just me then! Maybe I should go a little tighter on the 'slight drag' recommended for the feeler gauge.

But yes that would be very helpful thanks! Mine sounds like a diesel at idle ahaha

[coopman]

A valve adjustment is next on my list of jobs - here's a "pre" recording to compare with yours.

Sometimes I think the ticking is excessive, sometimes it seems ok - interested to hear your thoughts (my hearing is a bit broken at certain frequencies).

[otE30touring]

A valve adjustment is next on my list of jobs - here's a "pre" recording to compare with yours.

Sometimes I think the ticking is excessive, sometimes it seems ok - interested to hear your thoughts (my hearing is a bit broken at certain frequencies).

Thanks for this, thats very useful!

Yours sounds fine to me, slight ticking but not excessive. I remember before at certain RPMs I could hear my valvetrain more, but it sounded very similar to that. Mine now is louder than that, but still under load you don't hear the valvetrain at all really.

Its odd because my eccentrics didn't seem worn enough to cause any problems, I.e. I could set the 0.25mm clearance with no issues so I'd be interested to know how they sounded from the factory. I guess maybe just wear and tear has made it a bit more 'tappety' over time!

[boiliebasher]

Having messed out with my M20 over the years trying to get it to sound a bit quieter, I came to two conclusions;
1. Those M20 engines seem to be inherently "tappy" and it doesn't seem to adversely effect them too much.
2. Possiblity of valve stem guides worn (just like my M40'd E30) and it's a head off job to tackle that so most people just put with it and accept it's part of the characteristics of a 30 year old engine, with umpteen thousand miles on the clock originally designed and developed some 50+ years ago!

Obviously just my personal opinions but hope this helps!

[paultv]

Years ago I bought a new 525i E34 - 1987 if I remember correctly - best car I ever owned and very very quiet - so I think it's wear mostly with
the eccentrics and or the valve tops - although as I understand it the valves rotate as the engine runs - is this correct? so the tops should
wear evenly - grasping at straws here!!

I've taken to setting the gaps at the cam and not the eccentrics.

Paul

[otE30touring]

Having messed out with my M20 over the years trying to get it to sound a bit quieter, I came to two conclusions;
1. Those M20 engines seem to be inherently "tappy" and it doesn't seem to adversely effect them too much.
2. Possiblity of valve stem guides worn (just like my M40'd E30) and it's a head off job to tackle that so most people just put with it and accept it's part of the characteristics of a 30 year old engine, with umpteen thousand miles on the clock originally designed and developed some 50+ years ago!

Obviously just my personal opinions but hope this helps!

Thanks for this!

1. Yes agreed on this point, seems pretty normal and despite mine being loud it does run absolutely fine (in fact rather well)
2. This is a good point actually, although mine were quieter before I reset them all to factory spec so don't know if they were too tight before and valve train components are worn out or not. Either way my head will be coming off at some point down the line as I have a single broken manifold stud on Cyl 6. Might be a job for then...

[otE30touring]

Years ago I bought a new 525i E34 - 1987 if I remember correctly - best car I ever owned and very very quiet - so I think it's wear mostly with
the eccentrics and or the valve tops - although as I understand it the valves rotate as the engine runs - is this correct? so the tops should
wear evenly - grasping at straws here!!

I've taken to setting the gaps at the cam and not the eccentrics.

Paul

Thanks Paul! I believe I have read that somewhere yes. It looks like my best option here might be to set at the cam lobes then - what clearances did you use for that as I understand you have to factor in the ratio of rocker arm movement as well?

[boiliebasher]

Either way my head will be coming off at some point down the line as I have a single broken manifold stud on Cyl 6. Might be a job for then...
[/quote]

Well here's something to bear in mind when you do eventually pull the head off, check the exhaust manifold face. Wouldnt suprise me if it's warped a bit hence why there's a stud broken.....

[otE30touring]

Either way my head will be coming off at some point down the line as I have a single broken manifold stud on Cyl 6. Might be a job for then...

Well here's something to bear in mind when you do eventually pull the head off, check the exhaust manifold face. Wouldnt suprise me if it's warped a bit hence why there's a stud broken.....
[/quote]

Yes thanks for pointing that out - from what I've read it's wise to get it skimmed back to perfectly flat before refitting

[Lemon98]

This is mine idling straight after firing up so will be louder than when it's warm.

[HJ1981]

Damn, you guys make my M20B25 sounds like it is running on silk. But then again, recording the audio is different than actually hearing it irl.

Adjusting the valves is more of an art than just using the feeler gauge imo.

[BristolE30]

This is mine idling straight after firing up so will be louder than when it's warm.

Feel like Lemons sounds louder than yours otE30!

Sorry lemon..

[BristolE30]

I don’t think valve adjustment should be seen as a way of ‘quietening’ the engine down. They are ticky, let them tick. Adjust the valves for better performance and economy

[Lemon98]

This is mine idling straight after firing up so will be louder than when it's warm.

Feel like Lemons sounds louder than yours otE30!

Sorry lemon..

So?? It was for reference and his video was when the engine was warm. Mine is a cold start.

[BristolE30]

This is mine idling straight after firing up so will be louder than when it's warm.

Feel like Lemons sounds louder than yours otE30!

Sorry lemon..

So?? It was for reference and his video was when the engine was warm. Mine is a cold start.

Just messing with ya dude

[coopman]

I don’t think valve adjustment should be seen as a way of ‘quietening’ the engine down. They are ticky, let them tick. Adjust the valves for better performance and economy

Yeah, fair point. I'll be doing a valve adjustment anyway - the other reason being that it's fun...

[otE30touring]

This is mine idling straight after firing up so will be louder than when it's warm.

Thanks for this, appreciate the reference point! Mine still seems louder for some reason, oh and also the video of mine was when it was virtually stone cold so probably a pretty close comparison!

[otE30touring]

I don’t think valve adjustment should be seen as a way of ‘quietening’ the engine down. They are ticky, let them tick. Adjust the valves for better performance and economy

You do make a good point! No denying the fact that mine runs much better than it did before, just concerned about how loud the valve train actually was (in real life mine sounds almost exactly like my video in terms of volume). The ticking sound always dominates, even when stood at the rear of the car or when sat in inside.

[otE30touring]

I don’t think valve adjustment should be seen as a way of ‘quietening’ the engine down. They are ticky, let them tick. Adjust the valves for better performance and economy

You do make a good point! No denying the fact that mine runs much better than it did before, just concerned about how loud the valve train actually was (in real life mine sounds almost exactly like my video in terms of volume). The ticking sound always dominates, even when stood at the rear of the car or when sat in inside. I'm glad that no-one is overly concerned by my recording though, makes me a bit more confident!

[otE30touring]

Damn, you guys make my M20B25 sounds like it is running on silk. But then again, recording the audio is different than actually hearing it irl.

Adjusting the valves is more of an art than just using the feeler gauge imo.

I wish mine ran like silk! Yeah good point although the recording of mine sounds almost exactly the same as it does irl. Always have that ticking sound dominating.

Yeah I've heard that a few times actually, I've made a few adjustments to try to get it quieter but never wanted to go any tighter than the 0.25mm

[biffer]

Mine's silent when cold- it's when it's hot that it becomes more tappety. Is this the opposite to how these normally are?
For the record it has had its ex. manifold skimmed and broken studs replaced.

[otE30touring]

Mine's silent when cold- it's when it's hot that it becomes more tappety. Is this the opposite to how these normally are?
For the record it has had its ex. manifold skimmed and broken studs replaced.

Hmm interesting, I've heard from a few people theirs are quieter when hot but then again clearances are bigger when the engine is hot. I think I read the different use of materials on the top end means different parts expand at different rates hence the bigger clearance.

Either way yours being louder when hot could just be attributable to how certain valve train components have worn over time. And that's good to know, thanks!

[paultv]

I set at the cam using a basic rocker ratio of 1.4 ...... this of course isn't "correct" as the ratio changes as the cam lobe sweeps the rocker as it passes., changing the exact point of contact during the cycle.

Anyhow 7 thou is what I use which equals aprrox 10 thou at the valve which is a little tight but tickover is still fine and the engine is quieter.

I've heard of some who run 6 thou at the cam...I tried it bt the idle was very lumpy....although the car performed just fine with these different valve timings and was quiet when hot.

There's no evidence of valve burn at these settings...I'd done 25k with 7 thou cam and rebuilt the top end, valves were fine.

This is just my set up.... don't do anything you are not comfortable with.....

Paul

[otE30touring]

I set at the cam using a basic rocket ratio of 1.4 ...... this of course isn't "correct" as the ratio changes as the cam lobe sweeps the rocker as it passes., changing the exact point of contact during the cycle.

Anyhow 7 thou is what I use which equals aprrox 10 thou at the valve which is a little tight but tickover is still fine and the engine is quieter.

I've heard of some who run 6 thou at the cam...I tried it bt the idle was very lumpy....although the car performed just fine with these different valve timings and was quiet when hot.

There's no evidence of valve burn at these settings...I'd done 25k with 7 thou cam and rebuilt the top end, valves were fine.

This is just my set up.... don't do anything you are not comfortable with.....

Paul

Thanks Paul, appreciate the help here! This is all very useful to know - I may take a look at my lobe clearances this weekend and see if there is any room for adjustment there.

[paultv]

I have new eccentrics as my old ones had flat spots and the valve stem tops are worn...which the feeler bridges when you set the gap at the valve stem giving an incorrect measurement ie. always too big so I tried the cam side setting which I feel is more consistent and factors in any stem and eccentric wear.

So even if you're a bit out with the rocker ratio, your results are more consistent over the whole valve train.

Paul

[otE30touring]

I have new eccentrics as my old ones had flat spots and the valve stem tops are worn...which the feeler bridges when you set the gap at the valve stem giving an incorrect measurement ie. always too big so I tried the cam side setting which I feel is more consistent and factors in any stem and eccentric wear.

So even if you're a bit out with the rocker ratio, your results are more consistent over the whole valve train.

Paul

Thats very interesting to know actually, would not at all be surprised if that was the case on mine. I'll definitely take another look at that.

Thanks again for the help Paul!

[martauto]

I know it`s not the same car/engine, but the rocker arms on my escort mk1 were so badly worn (didnt notice until they were off) and a big groove had developed giving the same situation that Paul talked about.
I sorted them at work and what a sweet little engine she was.

Mart.