M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: bmwconnect on April 09, 2010, 10:23:04 PM
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I notice on the m42 I can advance or retard the cam timing without skipping a tooth. I was going to start playing around with it but I thought I would see if anybody on here has seen some gains with ajustment
Regards
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Back to -2 degrees, measured at the crank. gives more top end and a very smooth idle. Plus 2 gives a little tiny bit more mid range, idles comes and goes as the the box cycles O2 readings
Plus 5 gives a sometimes lumpy idle, more mid
Plus any more, and the idle gets weaker, power decreases over 5500
The best running car and midrange is about plus 2-3, fuel use gets better, as does mean dynamic compression at usable RPM of about 3600 or so .
Thats my experience with these cars. They are so weak that I mess with it. I have '93 cams .
Each crank notch is 6degrees FWIW. You need a good center line on the cams . The easiest way is too center the cam, move the crank.
I cant stand that my 400k Jetta 16v, kicks it all over the place.
They are about the same weight ( +-100#), the Motronic is supposed to be better than the M 1/ CIS VW system. The VW does have a knock sensor that the BMW does not have.
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Most interesting. I'm currently running 13psi on stock cams and 7000rpm limit but if I try and take it any further It's like hitting a wall so I guess the valves are floating. Would be neat if I could pull 7500rpm with some adjustment and not watch the boost drop. I could be dreaming though
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Back to -2 degrees, measured at the crank. gives more top end and a very smooth idle. Plus 2 gives a little tiny bit more mid range, idles comes and goes as the the box cycles O2 readings
Plus 5 gives a sometimes lumpy idle, more mid
Plus any more, and the idle gets weaker, power decreases over 5500
The best running car and midrange is about plus 2-3, fuel use gets better, as does mean dynamic compression at usable RPM of about 3600 or so .
Thats my experience with these cars. They are so weak that I mess with it. I have '93 cams .
Each crank notch is 6degrees FWIW. You need a good center line on the cams . The easiest way is too center the cam, move the crank.
I cant stand that my 400k Jetta 16v, kicks it all over the place.
They are about the same weight ( +-100#), the Motronic is supposed to be better than the M 1/ CIS VW system. The VW does have a knock sensor that the BMW does not have.
Forgot to thank you :)
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Back to -2 degrees, measured at the crank. gives more top end and a very smooth idle.
I am interested in a very smooth idle. What exactly means -2 degrees at the crank? How much should I turn the sprocket wheel and in what direction clockwise or counterclockwise?
Thank you.
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I played around with mine a few years ago & did not like it. You can move the power band around, but you won't see any gains overall. Aside form that, it didn't run very well at some RPM's since the ECU is not tuned for the changes, and my mileage dropped.
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Very interesting flyinglizard, I was just discussing the problem of smooth idle with cristimm the other days and we figured out we have never seen an m42 run smooth. I am also interested in this matter, so if you could give us a few more details on the adjustment I would be most grateful.
When the flywheel is locked in place with the original locking pin, at TDC, and I put the cam locking tool on the cams is should be at 0 degrees, right? So -2 degrees means keep the cams locked in place, unlock the crank and rotate it 2 degrees counterclockwise?
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correct me if I'm wrong but wouldn't it just be easier to loosen them cam sprocket bolts and then move the crank + or -
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Just zero the cam and crank, loosen the bolts, tap the crank in the run direction, a little less than 1/2 a crank notch. Keeping the intake at zero. leave the xhaust at zero.(let it move with the crank)
The midrange goes softer and the upper picks up . The change is pretty discreet. The idle can smooth out a little if the injectors are tight/clean, along with good plugs and wires. It is common to retard the cam with a turbo to add some vacuum and lower the boost RPM a little.
I am going to bump mine back up a little to get some midrange, but the changes are very little. This car has a new chain and guides. The chain will get loose and the new guide will have some run in . Net result, is that the cam will get latter in the first 2Kor so. I will reset the cams at the next LOF. 5K
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Just zero the cam and crank, loosen the bolts, tap the crank in the run direction, a little less than 1/2 a crank notch. Keeping the intake at zero. leave the xhaust at zero.(let it move with the crank)
The midrange goes softer and the upper picks up . The change is pretty discreet. The idle can smooth out a little if the injectors are tight/clean, along with good plugs and wires. It is common to retard the cam with a turbo to add some vacuum and lower the boost RPM a little.
I am going to bump mine back up a little to get some midrange, but the changes are very little. This car has a new chain and guides. The chain will get loose and the new guide will have some run in . Net result, is that the cam will get latter in the first 2Kor so. I will reset the cams at the next LOF. 5K
Thank you mike!
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Best idle is from Mustang injectors. I put my cams back to stock.
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I drove my 93 318is from Florida to Baltimore last July, (80 degree weather), and got 35.5 MPG expressway mileage doing about 75 to 80 MPH.
I recently had to replace my profile gasket and of course the head came off to do it. I just made the same trip, now with with new spark plugs, and I only got 33.5 MPG at the same speeds. The only difference was the April temps are 60 to 65 degrees.
I am wondering if set my cams a degree or 2 differently when I reassembled them, or does 20 degree cooler outside temperatures make the difference.
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^checked your tire pressure lately?
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I am going to bump mine back up a little to get some midrange, but the changes are very little. This car has a new chain and guides. The chain will get loose and the new guide will have some run in . Net result, is that the cam will get latter in the first 2Kor so. I will reset the cams at the next LOF. 5K
I totally forgot to do this! I changed the timing chain probably 40k miles ago, and I bet that I need to re-align the crank & cams. How much do you think the chain really stretches though?
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Funny. I set this car up last night. Both cams were a little late, enough to see with the eye.. I am pretty sure that the guide wears in a lot more than the stretch of the chain.
The car has run about 5k since chain/ slide replacement.
Bumped them both, idle speed came up a little, mid range, went from none to only weak.
Needs boost big time.
Re: air density correction is about 4-6 # of torque per 20* or more!!
My UL. plane leaves the ground in 125ft on a 75* day, and about 250 ft on a 90* day.
MM
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I opened my valve cover to change the gaskets and I took some pictures. As you can see the intake sprocket is not set in the middle of the oval holes.
Please tell me it is optimised for low-end torque or high rev power?
Another question: what do you think are the chain and sprockets original parts? (120k miles on the dash).
(http://dl.dropbox.com/u/649244/tmp/cams.jpg)
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The intake is back. This should idle very well, but without a crank reference, you have no idea where they really are. It may be at zero or not, you have to look at the crank mark to get it spot on. As the guide wears, the cams get later.
The chain wheels look very good, IMHO.
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Thanks. I was pretty pleased myself when I saw the condition of the chain and sprockets. Do you think it is plausible that they are the factory parts or have been changed at some point? (120k miles on the dash)
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mine were in similar shape and my motor has 230,000kms on it
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Thank you. So probably the parts are the factory ones. Are there any chances that the intake cam adjustment to be factory as well?
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My 1991 M42 failed emissions this year (Utah changed its emissions law and now includes a test at idle). It turned out my intake cam was advanced 7 degrees, as best I could tell using a protractor. I moved the intake cam back such that both cams were aligned with a straightedge (having no tool available) at TDC. I passed emissions easily and now have a nice smooth engine instead of a rough idle.
Centerpunch marks on the intake cam and sprocket indicate the PO had horsed around with various positions.
Fortunate for me I first tried to replace the vacuum and coolant hoses. I say fortunate because the plastic coolant pipe crumbled at all four connections upon removal. The throttle heater and vacuum hose delete worked out nicely, too.