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I’m sure it’s been covered, but “search” is not turning up what I’m looking for. If someone knows of a thread, please link me to it…
But…
What values are you folks adjusting your valves too? Bentley says 0.010" for both intake and exhaust (cold engine), but I’ve heard other values kicked around as well. Any suggestions?
OriginalSterm wrote:
[quote]I’m sure it’s been covered, but “search” is not turning up what I’m looking for. If someone knows of a thread, please link me to it…
But…
What values are you folks adjusting your valves too? Bentley says 0.010" for both intake and exhaust (cold engine), but I’ve heard other values kicked around as well. Any suggestions?[/quote]
The rules don’t provide flexibility on this. 0.010" it is.
Ranger wrote:
[quote]OriginalSterm wrote:
The rules don’t provide flexibility on this. 0.010" it is.[/quote]
Is that what the Factory Service Manual specifies? Bentley is not the manual referenced in the rules, ya know (despite its ubiquity and general acceptance as “the book”).
However, “9.3.1.2.6. No engine component may be modified in any manner not specifically permitted or authorized by the Factory Service Manual or Factory Technical Bulletins.” only speaks to modifying components. It does not say “no engine component may be adjusted or modified in any manner…”
Just stirring the pot…
Steve D.
I agree with Steve. You can adjust the engine to do whatever it’s capable of, as long as you don’t go substituting parts.
There is supposed to be a “hot setup” for valve clearances that is outside specifications. Maybe Robert or Jim will add to this. They guy who did my last valve adjustment supposedly used this method, but that was over a year ago. I’m sure they are way out now, I’m doing it before Barber.
DB
0.010 cold is the factory recommendation. You could go a bit tighter and gain a tiny bit of valve opening, but that runs the risk of a burnt valve. Are you feeling lucky?
jlevie wrote:
ditto on this you can run tighter if you want but don’t expect the valves to live a long life, that and to be honest I don’t think hanging the valves open is a secret to more power…
Hah! This sucks but thought I’d share it.
I set the valves a couple of weeks ago. The head was just sitting on the block with the head bolts finger tight.
Today I completed my double checking and committed to torquing the head bolts today. For some unknown reason, I decided to recheck the clearance. I can’t even get the .25mm feeler gage between any of theh valves and eccentrics now. I’m not sure I really understand why this is.
Temps are roughly the same as when I set the clearances. Maybe the little bit of lube that was on the gauge fooled me into thinking the gauge was moving around easier than it should have been. It’s not that I lubed the gauge intentionally, its just that I was “generous” with the lube when I assembled the head.
Anybody ran into this before?
Valve gap usually tightens when you fasten down the head. It’s a matter of the flatness of your head and your block. Inevitably one won’t be perfectly flat so your head is forced to bow a little. Any valve adjustment you do prior to fastening down the head is going to be rough.
For me, #3 and 4 always tightened a little when I fastened the head down. YMMV.
At the risk of being branded Ranger-esque, I attempted my first valve adjustment on Saturday, stone cold, following the “101 Projects” method. Yes, Levie, this is elementary maintenance stuff. Yes, it is much harder with no experience. :laugh:
I believe I have the valves adjusted too tight because they are almost too quiet, idle is rougher, starting is harder… Also I am getting a high pitched ~whistling sound. I need to grab another valve cover gasket, then retry.
I am using the spring-loaded BMW special tool for holding the eccentric. I was shocked at how little pressure it took to hold the eccentric against the feeler to get the right gap.
I had trouble holding the feeler, putting a little tension on the eccentric, and tightening the nut simultaneously. Is it bad to let the feeler lay over while doing the other 2 tasks? Surely someone wise and clever on here has a good trick.
PS - It’s the little victories that make me happy. I pressed a set of offset M3 CABs into lollipops over the weekend. My first try. The 'vert suspension-a-rama might start this weekend… :woohoo:
Way to go Steve! The best way to learn is to get your hands involved.
You won’t get the valves too tight when using the spring loaded adjuster. That is the purpose of the spring. If anything the gap may wind up a touch wider than desired. I loosen the clamp bolt, roll the eccentric back to make it easier to insert the feeler gage, apply spring pressure, release the feeler and tighten the clamp. Although hard to find now, a long single feeler bent at the end makes this an easier task than using a feeler gage set.
I’ve learned that the .010" number in the Bentley is more than is necessary. The valves can be adjusted cold to .006 for the intakes and .008 for the exhausts without risk to the valves.
The rough idle, starting difficulty and whistle can best be explained by an intake leak. It could be the gasket, breather hose, or something else that got disturbed during the valve adjustment. When replacing the gasket, always replace the four rubber bungs.
jlevie wrote:
Great info! Makes perfect sense to take that feeler out of the set and let it sit there while tightening the eccentric.
I’ll try to chase the leak. Could be a $hitty cover IndyJim sold me. But it looks nice painted black with the =====BMW===== sanded to expose the aluminium. :laugh:
I looked on realoem and don’t see rubber bungs associated with the valve cover. Can you give me more info?
Also, I failed to RTFM and follow the valve cover tightening order:
I am a little confused by #9. Is there one pair of nuts to secure the valve cover, then another pair to hold the spark plug loom on?
How narrow is the TDC sweet spot? I was shooting for getting the lobes down to the 5:00 and 7:00 positions(assuming the end of the rocker is at 12:00) but may have had a couple at 4:00 and 6:00. I was trying to turn the engine with a 22 mm wrench on the front, but I may try the rolling-in-5th-gear trick next time.
At one point, struggling to keep that d@mn wrench on the nut while rotating the engine I dropped an f-bomb loud enough that my daughter came out to see if everything was OK. 
To rotate the engine jump pins 11 and 14 in the diagnostic conector. I have a momentary switch set up for this and just plug it in and push it to rotate. Make sure the car is out of gear and the key is OFF.
You can adjust more than one valve at a time. Look at the lobes of the cam and you can do any of the ones that are down or pointed diaganaly down. When one is horizontal with the engine I wait till I rotate again as i don’t want any lift of the valve with the cam.
I don’t have the spring but use an alen wrench. I use the next size up feeler gauge from where I want to set them and typically when I set them this way and then check with the correct size it is perfect.
I never replace the valve cover gasket unless it gets trashed. Never had any problems. Sometimes I will hear a loud ticking while at the track. I can typically use a long screwdriver and narrow down which valve it is and pop off the cover and adjust as necessary.
Michael
Get some feeler gauges that are separate, each with their own handle. That way you can put the gauge in place and just leave it there. Then one hand applies pressure to the eccentric and the other hand tightens the nut.
There’s a DIY on my website that is written for the complete newby (by a complete newby) and is therefore 2X as long as necessary. Here’s my data point.
Center the lobes on the opposing cylinder (1-6, 2-5, 3-4).
Tap the rockers to ensure the valves are seated.
Stick the gauge in there. There’s is a technique to this that takes a little practice. It’s easy to get the feeler gauge hung up on the top of the valve stem and cause confustion. If rocker gap feels loose or tight, put in a feeler .002 thicker or thinner to confirm that it needs adjusting. If so , loosen the nut.
Push on the eccentric with a nail or BMW tool and move the gauge around. Adjust your pressure on the nail until the feeler gauge seems able to move around with a little resistance.
Let go of feeler and tighten nut down a little. Since you’ve let go of the feeler this this is a two handed, not 3 handed job.
Wiggle feeler and confirm that resistance didn’t magically change when you tightened the nut down.
Tighten the nut down the rest of the way. Confirm feeler gauge can still move with some resistance. Then grab the .002" thicker gauge and confirm that the rocker isn’t playing you for a patsy.
Good info, guys. Your instructions make so much more sense than last time I read them (which was before I had taken off the valve cover - or even thought about taking it off by myself).:laugh:
I use Michael’s technique as well. An offset feeler guage helps. I have a MAC tools set that they only sell in singles now. But this set should work well
http://www.oem-tools.com/product_info.php?cPath=19&products_id=1484
Ed
Go to your local BMW dealer and ask for the M20 motor valve adjusting tool. It is a spring loaded contraption that fits the eccentric and puts just the right amount of pressure on the feeler gauge for a perfect adjustment. Chuck
If you’re hesitant on doing the valve tune, I’d recommend SpeedTrapp Racing ( http://www.speedtrappracing.net/ ) to do the service for you, they’re very knowledgeable and know all the in’s and out’s with the M20’s - and great to work with.
It is very wide. If you ever get a chance to look a a cam out of the head you’ll see that most of the profile is a cylinder. As long as the rocker is on the cylindrical portion the vale adjustment will come out correct.
