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  #1  
Old 08-04-2006, 10:08 AM
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2mm measurement - interpretation please...

I did the valve adjustment last weekend and gave it a new valve cover gasket, also the valve cover itself developed a nice shine...

I took time to measure the timing chain stretch (cam timing) using the 2mm method - it was a real pain to get the dial guage just right for the measurement but that was the worst of it. Just to be sure here's what I did:

1) Removed valve lash (0 clearance)
2) Set the dial indicator on 2nd valve from the front (Intake) resting the foot of the indicator on the cam follower
3) Rotated the engine Clockwise at the crankshaft until I got 2 mm valve lift (had to do it a couple of times to get it just right).
4) When it reached 2mm lift I noted the reading at the balancer - it was 14-15 degrees (see the terrible pic attached)

According to what I've read I should now subtract 11 degrees for the used chain on OE617.952, therefore 15-11=4 degree stretch, right?!

How is that - is this tolerable or do I need a Woodruf key?! If so, what size?

Also, would I need to be concerned about IP timing being off with this chain stretch?! The marks on the IP are lined up perfectly (don't believe it was touched).

What say ya?
MF

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2mm measurement - interpretation please...-hansi_15deg_atdc.jpg  
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  #2  
Old 08-04-2006, 11:08 PM
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Let's try again...

Anybody............... !?

Somebody please comment on the measurement - I'm hoping I've got some time to go before I have to roll a new chain but looking for another opinion...

Please...
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  #3  
Old 08-04-2006, 11:32 PM
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i think their is a woodruff key that you can install and get rid of some of the stretch
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Old 08-04-2006, 11:59 PM
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According to what I've read I should now subtract 11 degrees for the used chain on OE617.952, therefore 15-11=4 degree stretch, right?!


Took me a bit to find the timing chain article. I believe that you are correct in that you have 3-4 mm stretch (14-15 minus 11). I read that the smallest offset key you can get adjusts 4 degrees.Part #6219910467. It's only my opinion but I wouldn't change the key just yet.

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  #5  
Old 08-05-2006, 02:30 AM
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That reading is not for chain stretch it's for cam timing. Now that you know what the cam timing is you can use that as a bench mark. Somewhere there is a chart that shows what the cam timing spec is for you cam. If the timing is off you can get an off set woodruf key to correct this.
Also go ahead and check pump timing. late pump timing will give you lousy performance and poor fuel economy.
I don't think you can use that measurement to determine when the chain should be replaced.
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  #6  
Old 08-05-2006, 10:43 AM
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Generally, an elongation of the chain of 4 is probably not worth bothering with. It certainly does not indicate a requirement to replace the chain.

If you have the time........and wish to go through the bother........you could obtain a Woodruff key with a 4 offset and return the timing to spec. However, this is not without some risk and some effort. You must remove the tensioner and remove the cam sprocket. During this process you always run the risk of dropping a part/Woodruff key/thrust washer down into the chain gallery........with the commesurate huge amount of work to retrieve it.

As mentioned, if the cam timing is late, the IP timing is also late........marks on the outside of the pump notwithstanding. Check the pump timing with the RIV tool if you can borrow or rent one..........it will fit a 1985 617...........it's extremely accurate and you can set timing in 10 minutes. There are a couple of them in the tool rental program. They do carry a hefty deposit for the rental due to their purchase price.
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Old 08-05-2006, 07:19 PM
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http://diymbrepair.com/easley/iptiming.htm You can use this method to check pump timing. It works well with no special tools to rent. Pump timing is your best bang for the buck so to speak.
When I get caught up with all my customer work I will set the cam timing on my "Beirut Cruzer" but it's on a long list of things to do.
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Old 08-05-2006, 08:26 PM
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What you have to keep in mind is MB allows for 2deg of wear out of the factory. So the question would be is 2deg normal or is it better to bring it back to zero deg?

I don't know if I would worry so much about 4 deg. Just change your oil at the proper interval and keep an eye on it.

Also, keep in mind you should also be checking the condition of your rails, tensioner and slide.

Danny
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  #9  
Old 08-06-2006, 04:45 PM
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Adjusting IP timing...

Quote:
Originally Posted by Brian Carlton View Post
Check the pump timing with the RIV tool if you can borrow or rent one..........it will fit a 1985 617...........it's extremely accurate and you can set timing in 10 minutes. There are a couple of them in the tool rental program.
Thanks for your replys - sounds like adjusting IP timing will be my next project. I just sent a couple of PMs to the folks in the Tool Rental probram - hopefully I'll get a response from one of them or I can use the procedure from OMEGAMAN - looks like no special tools are required.

One question - I've been sizing up the IP pump trying to find all the screws that I'll need to loosen (supposedly 4 screws) - I only see two of them and the one between the IP and the engine looks like it will be a bear to get to...

Anybody have a diagram on where the screws are located on the IP so I have a better idea!? I'm sweating any work related to Timing and/or IP...
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Old 08-06-2006, 05:38 PM
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Quote:
Originally Posted by MercFan View Post
One question - I've been sizing up the IP pump trying to find all the screws that I'll need to loosen (supposedly 4 screws) - I only see two of them and the one between the IP and the engine looks like it will be a bear to get to...

Anybody have a diagram on where the screws are located on the IP so I have a better idea!? I'm sweating any work related to Timing and/or IP...
No diagram, but three cap screws are easily found on the IP forward flange. One is down underneath.

The fourth cap screw is a nightmare. The first problem is finding it. You must find it without the capability of seeing it. It lives way down at the bottom of the IP and you must access it from the top of the IP with a very long box wrench. The wrench doesn't have enough swing with the rack damper pin in place, so, you'll have to remove that. Also, you may need to bend the wrench slightly to give the head a touch of offset, otherwise you'll not get it onto the head of the cap screw.

Now, to find the cap screw...........you need to lay on top of the engine and peer down with a strong light between the IP and the oil filter housing. Look down in the space between the rack damper screw and the valve cover. Way down there, you might just be able to see the very top of the cap screw. Then, you must thread the box wrench all the way down and pick up the cap screw and move it 1/12 of a turn. It's damn near like surgery.........like I said.........a royal PITA the first time you do it.

If you had any thoughts of checking out this screw from below, you can just dispense with that idea right now. It's invisible from that angle.
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  #11  
Old 08-06-2006, 11:42 PM
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Whew...

Quote:
Originally Posted by Brian Carlton View Post
The fourth cap screw is a nightmare. The first problem is finding it. You must find it without the capability of seeing it. It lives way down at the bottom of the IP and you must access it from the top of the IP with a very long box wrench. The wrench doesn't have enough swing with the rack damper pin in place, so, you'll have to remove that. Also, you may need to bend the wrench slightly to give the head a touch of offset, otherwise you'll not get it onto the head of the cap screw.

...like I said.........a royal PITA the first time you do it.
Depressing... we'll have to see if I can even find it...
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  #12  
Old 08-09-2006, 12:37 AM
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Rack damper pin...

Quote:
Originally Posted by Brian Carlton View Post
The wrench doesn't have enough swing with the rack damper pin in place, so, you'll have to remove that...
Couple of questions about the rack damper - I've searched the forum, but found no definitive answers on this:

1) Is it possilble to remove the rack damper pin WITHOUT removing the oil filter housing first?! THere's just very little room there to maneuver...

2) What risks are associated with removal of the rack damper pin - it seems mine is screwed IN all the way (old silver kind).

3) Is it best to replace the old rack damper pin for the new style or leave it alone if the car doesn't have related symptoms.

4) If I were to remove it, what adjustments would I have to make when re-installing...
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  #13  
Old 08-09-2006, 12:45 AM
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I would leave the pin alone unless there are problems. If it idles fine it should be ok. If it's screwd in all the way the car might not idle when it's cold in the winter but you'll have to wait and see.
The screw does come out without removing the oil filter housing.
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  #14  
Old 08-09-2006, 12:51 AM
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Quote:
Originally Posted by MercFan View Post
Couple of questions about the rack damper - I've searched the forum, but found no definitive answers on this:

1) Is it possilble to remove the rack damper pin WITHOUT removing the oil filter housing first?! THere's just very little room there to maneuver...

2) What risks are associated with removal of the rack damper pin - it seems mine is screwed IN all the way (old silver kind).

3) Is it best to replace the old rack damper pin for the new style or leave it alone if the car doesn't have related symptoms.

4) If I were to remove it, what adjustments would I have to make when re-installing...
1) Yes.

2) None. Just loosen the locknut and unthread the pin.

3) The new one has a spring with more tension. You can thread the old one all the way back in for the maximum tension available (but don't bottom it out) or you can get the new pin (pricey).

4) With the old one, you'll need to get it compressed just about all the way.........but don't bottom it out. If it goes too far, you'll have trouble starting it when cold.

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