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  #16  
Old 02-23-2003, 09:07 PM
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Location: Evansville, Indiana
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Gary:

The easy way is to line up the mark on the sprocket or thrust washer with the mark in the cam tower, then read the balancer for the timing. This is accurate enough for measuring wear. The method using the change in position of the valve is much more difficult, and isn't necessary to find out if the chain is shot.

3-4 degrees is fine, providing the chain was tight (make sure the tensioner rail is pushed in against the chain while cranking the engine over) and that you rotated the engine in the normal direction, as I am sure you did.

Drip method works great.

Peter
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  #17  
Old 02-24-2003, 08:28 AM
Gary Scarsella
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Thanks Peter. That is good news.
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  #18  
Old 02-24-2003, 10:00 AM
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Has anyone used both methods back to back to measure chain elongation ... to compare the results of the two methods ? I worry that with the "easier" method that something is being lost.. like a factor which might have the wear from two items offsetting each other..

I would also argue that the dial indicator is not a hard procedure.... you can get the tools for $25 or less... and know you are doing it like the engineers specified....Since it is "rather" important to valve timing... and you are measuring the valve timing directly when you use the dial indicator... it might be worth it for accuracy and longivity out of one's engine....
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  #19  
Old 02-24-2003, 08:20 PM
Gary Scarsella
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According to the "easy" method, my chain is 3 degrees from new. I think I'll try the other method if I can find a good explanation on my CD manual then see how that compares.
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  #20  
Old 02-25-2003, 10:20 AM
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I stole this from a Stevebfl (moderator) post :

I have looked at hundreds of MB timing marks (at the cam) and they are only
accurate enough to know which tooth to line up. There is 18degrees between
each tooth. If you marked and followed your own specific motor you might could
form a judgement. To just drop in and view it isn't good science.

The proper way to do it is very simple. The valve clearance is removed and the
engine rotated till the intake valve on number one cylinder is pushed exactly
2mm down by the cam lobe. Any resonable dial indicator will measure this.

When the motor is in this position the crank position is read from the crank scale
and indicator and compared to the book value. In the case af a 617.95 motor
with cam ID 11 it should say 11deg ATDC. If it says 21deg then there would be
ten degrees of stretch and a new chain would be in order.

I threw that 10deg increment out because I consider that much to be obvious,
it might take 350,000 miles to stretch one that much though and if asked I say
replace it at 200k. I very seldom measure chains by anything more than mileage
and noise. I would replace anything in doubt over 100k. (ALL mileage numbers
are my opinion only!!) (The timing numbers for cam ID 11 came from 1985 TDM)
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  #21  
Old 02-25-2003, 10:31 AM
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OK, Steve mentioned something I have not seen before... the fact that cams differ AND that a certain number of degrees must be subtracted from the reading on the crank to give the accurate degree of stretch...

I have seen this done by someone who knew what they were doing... so I will add one thing...

You either need a 'bridge' over the cam to set a regular magnetic base dial indicator base on or you need one of those twistable/lockable segmented arms to hold the indicator....
The bridge should be steel if you want the magnet to hold it...

The trick is that you are wanting to get the dial indicator in line with the actual valve stem.. the top of which you need to reach with the indicator... I went and bought a two inch extension for mine to make this easier because I want to use the bridge... if you have the twisty you can get to it from another mounting location and don't need the extra length...
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  #22  
Old 02-25-2003, 10:40 AM
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I believe I can see in mind this setup, but just to make sure (and for others ), can someone take a picture of the setup and post it?
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  #23  
Old 02-25-2003, 11:38 AM
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I think the only camera available when Bill and I watched TCane do this was Bill's.... he is at new work site today and may not be online... may be this evening before he can access his pics of this.. unless he already sent them to the " FAQ Pages" which his sister was setting up ....
If it helps any .... you are trying to get the dial indicator directly in line with the valve... above it... then you get the cam into the proper position ( a place where it would not be affecting the valve at all... the lowest place on the cam... then you take out all the slack by adjusting the nuts on the top of the valve stem... TO ZERO.... where you would normally be setting it to a number like 4 thousandths...... so when you turn the crank, which turns the cam... you are measureing the amount of rise in the cam lobe off of flat... by measureing it pusing the valve downward... by having the dial indicator stem positioned on the top of the valve....
If you don't understand from that just ask more questions... I am snowed in this morning and have plenty of time....LOL... that also means I am not going out and getting pics of this setup today...LOL... sorry.... love my digital camera too much to risk freezing it...
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  #24  
Old 02-25-2003, 04:08 PM
Gary Scarsella
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Makes sense. I am going to try this in the next day or two and take some pictures. The important thing, to me, is adjusting the clearance to exactly zero. There is be room for plus or minus anything. I know harmonic balancers, on other cars, have a tendency to move/shift and not show precise measurement. Is this true of MB?
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  #25  
Old 02-25-2003, 04:18 PM
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You just unscrew the adjusting cap on the valve until it contacts the cam.... then hold it still with a wrench and bring the locking nut up to it to lock it in place... very straight forward....( the rocker arm will still be between the valve and the cam but does not change this concept)...

Last edited by leathermang; 02-25-2003 at 04:23 PM.
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  #26  
Old 02-27-2003, 08:34 PM
Gary Scarsella
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Here are some pictures of how I set up for the dial indicator method. When the intake valve was compressed 2mm, the crank pulley showed about 16 degrees. Does anyone know the degrees a non-stretched chain would show on a 1976? The "easy" method showed I had about 3 degrees of stretch. Please comment on the pictures if they help or not. It was difficult to get good shots with the lighting I had. You can zoom in to see more details.
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  #27  
Old 02-28-2003, 08:33 AM
Gary Scarsella
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I did the dial indicator method last night and found it pretty easy. I took some pictures but am having a hard time posting them on the web site. The reading, for my '76, was about 16 degrees. I need to find the degrees it should be with no chain stretch to subtract that from 16. The "easy" method showed about 3 degrees chain stretch.
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