Pagoda SL Group
W113 Pagoda SL Group => General Discussion => Topic started by: merrill on April 10, 2007, 19:27:38
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so, I have my newly rebuilt motor in the garage back from metric motors and I wanted to install the distributor before installing the motor.
the timing mark on the cam is aligned up and the crank pulley is at 5 deg atdc.
metric told me that the motor should be at tdc, should I go ahead and install the distributor or should I set the cramk pulley at 3 deg btdc (on compression stroke) and install the distro then?
thanks
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Metric sent you a 'rebuilt' motor with the cam and crank out 5 degrees?
You might want to invest in an offset key?
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Hello Matt,
It is ok for the cam marks to be a little late. They syould never be early. A single timing chain link is 18 degrees. You can use offset keys on the camshaft to get the timing a bit closer if you wish, but it usually will not make a noticable difference. A mose precise way to time the camshaft is with a dial indicator. This has been discussed here many times. This will take into account any changes in the geometry of the head and its moving parts after the machining involved in the rebuilding. This kind of "tweeking" can happen during another tunning.
The engine should start fine by setting the cam/crankshaft marks as close to specs as possible (the camshaft mark should never be early). Slide in the distributor and static time it so that the ignition points break (open) at 4 degrees BTDC. (static timing). Make sure that both cam lowbes for #1 are upward (compression stroke). Hopefully you kept track of the injection timing and it is not 180 deg. off. It's nice to get the ignition distributer oriented in the correct direction as original. If you have the original distributer in your 230SL the vacuume cell is oriented at 6:00 o'clock as you sit in the driver's seat. On a 280SL with original distributor orientation is at 1:00 o'clock as you sit in the driver's seat. Refer to one of many photos in the BBB if needed.
With this static timing set-up the car should start and "tweeking" can begin. Be very cautious not to "air lock" and overheat the engine. Watch the temperature as it warms. Re-torque the head after first complete warming cylcle and at 500 miles. Always loosen the radiator cap before re-tightening the head.
During initial starting, leave fuel injection lines cracked open at the injectors. Crank the engine with throttle all the way to the floor. Watch for oil pressure to rise. When fuel emerges at each injector fittings tighten the lines as needed. Starting will commence soon! Watch temperature and for oil pressure. Allow the engine to cycle through several complete warm up cool downs before heading out for a test drive. Check for leaks during these times. This also allows the new parts to become aquainted with each other "gently getting to know each other".
Happy Motoring!
Joe Alexander
Blacklick, Ohio
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Joe, What am I missing here? If you measure the valve opening with a dial gauge, you still have to use a offset key to get it right. I don't think the average '113SL' groupie is going to do the dial gauge thing, but could do a offset key to aligne the cam index and TDC. Book says the 230SL intake opens 10 degrees BTDC and closes 58 ATDC- total 68 open(33 overlap with exhaust valve). Seems 5 degrees off effects performance and ignition timing. What say ye?
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so, I posed the question to metric motors and this was the reply,
(2 e mails)
e mail 1
Hey Matt - We set the cam timing at 0 deg / t.d.c. cyl#1. If it looks off then we likely have an offset woodruff key in the cam which pushes the cam into proper timing but the timing mark stays in the same spot so it can look decieving.
e mail 2
Matt - It's true you can check the cam timing with a dial indicator but our specs show it at a certain degree @ 2.0mm of lift. anyway we just use the marks and never have any problem with it.
If you decide to use the dial indicator let me know and I'll fax you the correct spec out of the true tech data book.
Actually I am kind of disappointed that they did not set the valve timing per the opening of the valve. For $5,900 it seems that it should have been part of the rebuild.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Matt, Is an offset key in there?
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Hello Matt,
I agree, the off set key normally makes no noticable difference.Five degrees is minimal. This will not affect the ignition timing, you set it independantly. I can show you instances in some BBBs where they say "offset keys are available but normally do not make a noticable difference".
Consider this; a new engine is in perfect valve time only for a short time before the settings change. From day one the chain and sprockets begin to wear and streach. So the engine spends most of its life running with later valve timing than when it left the factory. The overlap of the valves does not change. the engines are designed with an allowable tollerance on such things as this. One complete link of stretch is 18 degrees. I do not normally become concerned unless the marks are off more than 8 degrees on a used engine. Five degrees is a little much for a new engine, but not a real concern.
The reason your engine is five degrees off even with all the new parts is that if the head was resurfaced a certain amount, then the timing chain becomes too long by twice that amount. Any sprocket wear also makes the chain and valve timing a little late. Timing marks are a method to set the cam timing on a new engine. On a used or rebuilt engine the geometry of things changes a bit from machining and wear. Setting everything up with a dial indicator is the most precise method. It may not make a noticable difference unless things are really out of whack.
Joe Alexander
Blacklick, Ohio
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Joe, Glen
so, there is no off set key installed on the cam sprocket.
also, the cylinder head was cut at metric, "minimal cut" 84.9mm what ever that means.
the cam lobes for no 1 are pointing between 9/10 and 2/3. crank is at 5 deg btdc and cam timing is before the mark.
so, i think the motor is at tdc, I am gong to install the distributer and inj pump at 20 deg atdc. from there I will follow the bbb instructions to check the valve timing.
based on the joe's second reply I bet I end up installing a 2 deg offset key.
might as well do this now before the motor is installed.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Hello Matt,
Just to clearify things.... When your crankshaft is at Zero TDC, your camshaft marks should be aligned or a little late. Never early! So you are saying that when your cam marks are aligned, your crankshaft marks are 5 degrees After top dead center. I interperate this as meaning the cam timing is 5 degrees late. Always turn the engine in the normal direction of rotation for these settings.
Joe Alexander
Blacklick, Ohio
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Hello Matt,
The following off-set keys are available;
621 991 0467 4 degrees
621 991 0267 6.5 degrees
621 991 0267 8 degrees
621 991 0067 10 degrees
Joe Alexander
Blacklick, Ohio
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Matt, You have to look at the woodruff key actually on the shaft to tell if it is offset. If the crank pointer says 5 deg BTDC, it is 5 deg BTDC no matter what the cam lobes say. Take No 1 plug out and view the piston on its travel. Object is to get all these parts in sync- crank, cam, distributor, FI pump, valve clearance, etc. Knowledge is Power. That's why MB dealers get $100/hr for service. Unfortunately for them and us, they don't have anybody expert on 113s.
Is there a Communication gap with Metric?
quote:
Originally posted by merrill
Joe, Glen
so, there is no off set key installed on the cam sprocket.
also, the cylinder head was cut at metric, "minimal cut" 84.9mm what ever that means.
the cam lobes for no 1 are pointing between 9/10 and 2/3. crank is at 5 deg btdc and cam timing is before the mark.
so, i think the motor is at tdc, I am gong to install the distributer and inj pump at 20 deg atdc. from there I will follow the bbb instructions to check the valve timing.
based on the joe's second reply I bet I end up installing a 2 deg offset key.
might as well do this now before the motor is installed.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Joe,
So you are saying that when your cam marks are aligned, your crankshaft marks are 5 degrees After top dead center. I interperate this as meaning the cam timing is 5 degrees late. -
yep, when the motor came out of the crate the crank mark zero (0) was pointing straight up and the cam was not ligned up.
so, when I turned the crank to get the cam marks ligned up, the crank was at 5 deg atdc at the pointer.
the cam lobes for no 1 at between 9/10 and 2/3 o clock.
as far as the key, I removed the bolt and washer for the cam sprocket. I could clearly see the key and the notches in the cam and the sprocket were ligned up.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Matt, A non-offset Woodruff is flat on both sides. An offset key 'offsets' the arc portion in the shaft from the section in the spocket by the number of degrees it is. An offset key is not flat on both sides. The offset is the line where the shaft meets the spocket. You gotta take the key out of the shaft to positively determine if it is offset. Apparently, the Metric guy can't say for sure what is there. C'est la vie or whatever in German.
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Hello Matt,
Yes as you describe, your cam timing is 5 degrees late. It sounds like a 4 degree off set key will put you very close to the mark. Make sure your block pointer is not bent.
Joe Alexander
Blacklick, Ohio
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Don't know about your's(?), but on mine it is 2 degrees on the crank are one on the cam. The offset has got to be in the right direction.
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Hello,
Good observation Glenn. Well I guess the next question are the off-set keys calibrated for the crank timing or the cam timing? They are inexpensive so you may want to order a few of them.
Joe Alexander
Blacklick, Ohio
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Joe, My guess it has to do with the diameter of the shaft it is on(Geometry). MB's guess-who knows? As you say, try a couple and find out.
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This is a very informative thread but I have never seen an offset woodruff key.
Does anyone have a picture they can add?
thanks
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
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Bob, No pix, but visualize a sprocket on a shaft with the key ways lined up precisely with no key present. Then rotate the sprocket 2 degrees- and, viola, you have the profile of a 2 degree offset key. Obviously, the key becomes weaker as the offset grows, until the keyways pass each other. Say the key is 1/8 inch on a 1" shaft, 1 degree is -- you do the geometry- ? .oooo? inches.
I guess offset key are one way to sync two sprockets. Could adjust the belt or chain length or idler position. When they're all in sync-crank, cam, distrib, oil pump, FI pump, fan, diff, Mars, Venus, etc.-- That 250 will run smooth as silk- balance a Jefferson nickel on the valve cover.
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wow, this thread has got a lot of attention. after reading the last few posts, I want to clarify something.
According to the bbb, etc, the goal is not necessarily to make the crank be at tdc at the pointer and the cam marks to align.
the goal is to make sure the no 1 intake valve opens .4mmm when the crank is at zero tdc. ALSO, according to the manuals, when the valve is open .4mmm and the crank is at zero tdc there is a distance between the valve and the top of the pistion that should also be verified. The bbb also states one should check both the intake and exhaust valves?
I must admit I have no idea how one would actually measure the distance between the .4mm open valve and the top of the piston.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Download Attachment: (http://images/icon_paperclip.gif) RonWoodsKey3.jpg (http://www.sl113.org/forums/uploaded/merrill/200741393039_RonWoodsKey3.jpg)
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Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Download Attachment: (http://images/icon_paperclip.gif) keys.jpg (http://www.sl113.org/forums/uploaded/merrill/200741393237_keys.jpg)
20.72 KB
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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so,
here is more info on keys and another photo
Camshaft Woodruff Key
An offset to the right(in the direction of rotation) results in an earlier valve opening, while an offset to the left results in a later valve opening.
5 Degrees: 1.3mm = 10 deg. at crank
4 Degrees: 1.1mm = 8 deg. at crank
3 Degrees: 0.9mm = 6.5deg. at crank
2 Degrees: 0.7mm = 4 deg. at crank
if needed one can also remove a link and add a key to correct timing
Download Attachment: (http://images/icon_paperclip.gif) offset.jpg (http://www.sl113.org/forums/uploaded/merrill/200741395627_offset.jpg)
14.14 KB
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Matt, I assume the BBB means .4mm tdc on the exhaust/intake stroke, not the compression/power stroke. Cams would be pointing down. Crank - one rev, Cam - 1/2 rev.
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Glen,
actually yes. the bbb does mean the intake stroke or exhaust stroke.
one is measuring the opening of the valve .4mm and verifying the crank location.
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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quote:
Originally posted by merrill
so,
here is more info on keys and another photo
Camshaft Woodruff Key
An offset to the right(in the direction of rotation) results in an earlier valve opening, while an offset to the left results in a later valve opening.
5 Degrees: 1.3mm = 10 deg. at crank
4 Degrees: 1.1mm = 8 deg. at crank
3 Degrees: 0.9mm = 6.5deg. at crank
2 Degrees: 0.7mm = 4 deg. at crank
if needed one can also remove a link and add a key to correct timing
Download Attachment: (http://images/icon_paperclip.gif) offset.jpg (http://www.sl113.org/forums/uploaded/merrill/200741395627_offset.jpg)
14.14 KB
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
Matt,
Great pics and info,
Thanks
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
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so,
here are the current part numbers for the offset keys
621 991 04 67 2 deg at cam 4 at crank
621 991 02 67 3 deg at cam 6.5 at crank
621 991 01 67 4 deg at cam 8 at crank
621 991 00 67 5 deg at cam 10 at crank
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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The valve timing can only be set with a dial gage and a degree wheel on the cam shaft.
The correct setting for checking valve to piston clearance is 5 degrees ATDC on number 1 piston. You need to use a dial gauge and push down on the intake valve until it hits the piston. You need about 1 mm of clearance.
The piston actually slows down and stops when it reaches either end of it's travel as the crank goes over center. Since the piston stops but the cam shaft keeps moving the valve will get very close to the piston at 5 degrees ATDC until it starts to move down in the cylinder.
The off set key moves the cam shaft and not the gear so the guy at Metrics is being straight with you about that. If there is no off set key and the marks are out slightly it's not the end of the world. Unless you do the valve timing test according to the BBB it's all suposition anyway.
Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org
1 877 661 6061
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Hello Matt and Dan,
I see the point Dan and the fellow at Metric are making and I correct my previous post. As noted, the off keys will get the actual cam timing closer but will make the alignment of the cam timing marks off even more! Does not make sense, but true. Do not mistakingly put the off-set key in opposite. If you do the alingment marks will be closer but the actual cam timing will be off even more.!
I guess if you use the off set keys, be prepared to use a dial indicater to do the valve timing.
There is always something to learn here by this group, even for the experienced!
Joe Alexander
Blacklick, Ohio
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One more thing:
The woodruff key carries no lateral tourque and so it should never break off. When you tighten the screw it presses the gear against the cam shaft and prevents it from turning. The woodruff key is there to set the relationship between the cam gear and the cam shaft with the intent of keeping the cam shaft and crank shaft in time with each other . The woodruff keys on the distributor drive and on the crank shaft act in a similar fashion.
Only the cam shaft is provided with an off set key to make adjustments for machining and other variations. The trick is to always use a new crank shaft gear if you have the bottom end apart. The crank gear has to run the cam shaft, oil pump, distributor, injection pump and idler gears. It takes a pounding and wears out twice as fast as the cam gear. If the teeth on the cam gear are pointed you can bet the crank gear is badly worn. Best bet is to replace all the gears during rebuild.
Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org
1 877 661 6061
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so, I finally checked the valve timing today.
followed the bbb in structions and found the timing to be off 2 maybe 3 deg atdc at the crank. so the cam timing is probably off 1.5 to 2 deg off
just for fun I checked the valve clearence and it was dead on so for now I will leave the current woodruff key in .
once I get the motor running, I will check the timing again.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Dan,
your reply made me double check the bbb and the timing correction.
per the bbb if the crank timing is off, the cam timing is off half that amount.
so 4 deg at the crank would be 2 deg at the cam.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
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Blacklick topic---JA et al. Sounds like there should be a 'Engine Fundamentals 101' at Blacklick. How cranks, pistons, cams, distrib
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quote:
Originally posted by glennard
Blacklick topic---JA et al. Sounds like there should be a 'Engine Fundamentals 101' at Blacklick. How cranks, pistons, cams, distrib
utor, FI pump, oil pump, fan, plugs, etc, etc, all work in sync.
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Hello Glenn,
Yes we will have a "take apart engine" on a stand for the tech session so we can disect it and reveal these mysteries!
Joe Alexander
Blacklick, Ohio