Chain stretch... 10 degrees BTDC? - Page 3 - PeachParts Mercedes-Benz Forum

81Wagon · #31 08-01-2008, 07:18 PM

My high school geometry teacher would get literally red in the face and then he'd kick his stool over when the students frustrated him... which was often

. The stool was about four feet tall and only a foot in diameter, so you can imagine our amazement when one day he kicked the thing all the way across the room and it didn't so much as wobble - it landed on all four feet and came to a perfect, upright stop. There was some geometric precision for you

.

Anyway, I just realized... How do I identify a woodruff key versus the stock "single edge key" that should be under the cam gear?

Quote:

Originally Posted by barry123400

The pump sounds like it will probably be off a simular amount. Since that is not certain by any means turn the crank with the pump in about the centre of it's adjustment range until the fuel flow just stops. By reading the crank degrees you will know exaclty how much to move that pump. Remember its half the crank degrees you want to correct at the pump I think. Otherwise it probably is open the timing chain up time. Overall not too serious to correct and should really give you a much better running engine when you are through. I am tired this evening so will review this post tomorrow for any errors.

Thanks. Couldn't it just be whatever is causing my -9 degree offset that's thrown the pump out of range, though? I guess we'll find out soon enough since I'm definitely going to fix the timing chain issue first.

Thanks for your help, guys!

jt20 · #32 08-01-2008, 07:24 PM

the woodruff key is a type of key - a generic term for the keys being used on camshaft.

the profile of the offset keys are S-shaped

the profile of the original key is simply a rectangle.

jt20 · #33 08-01-2008, 07:28 PM

first drawing is the original

second is the offset

you are looking a the camshaft with the cam gear removed at the front of the engine

81Wagon · #34 08-01-2008, 07:50 PM

Thanks. I'll check it in the morning!

81Wagon · #35 08-03-2008, 07:22 PM

Okay... This is what I found.

I pulled the gear forward about half a centimeter. The camshaft appears to be smooth except where the alignment marks are; there is a raised square knob there (see pics).

Is that where the woodruff key would be? If so, is it the 'stock' key or an adjustment key? Based on jt20's description I'm guessing it's the stock one.

Thanks...

#36 08-03-2008, 07:31 PM

That first one looks like there is a shoulder on the key which means its an offset one.

81Wagon · #37 08-03-2008, 09:27 PM

I looked at those pictures from Fastlane and I was having a hell of a time figuring out how they worked. Now that I get it, it seems so obvious! The part they label "bottom" is what I would consider the top, though. That really threw me off!

Unfortunately, it looks upon closer inspection (and with better understanding!) like the one I've got is the stock key, not an offset key. So now the question is, what could be causing this and how do I fix it?

81Wagon · #38 08-03-2008, 09:42 PM

I suppose I can install a 10 degree key in reverse, right? That should put it back to spec. But that doesn't solve whatever caused this to begin with...