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Reinier

L28 TDC questions

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Hi guys,

I'm adjusting my cam/valve timing on my L28 and since it's the first time I have a few questions I hope you guys can answer for me.

1. Which of the 5 marks should I use on the camshaft pulley? See picture. Some sources say the first and other sources say the second. It doesn't really matter with setting the chain on the camshaft but it does matter a lot with reading the timing notch and grove on the camshaft sprocket. Which brings me to question 2.

2. Reading the timing notch and grove on the camshaft sprocket is clearly a very precise thing but how can I do this accurately? Just 1/20" (1mm) rotation on the crank makes a lot of difference on reading the notch and groove.

3. I'm turning the engine with a socket on the camshaft bolt and It's impossible for me to turn the crank small amounts needed to line up the crankshaft pulley marks correctly. I need to apply quite some force to get it to turn and than it shoots a long part. I did remove to spark plugs so it's not the pressure build up in the cylinders. Is this normal or is my engine not rotating as smooth as it should? Or is it because I'm using the camshaft bolt instead of the crankshaft bolt?

Thanks in advance and sorry for the noob questions but I haven't done this type of engine work before.

tdc.jpg

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Sorry, but if you have not done this before.. first buy yourself (or download) the service manual for that particular engine.. without a serv. manual you can NOT put something like an engine together in the right way..

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I have the service manual,  the Haynes manual, two books on the L-series engine and two other 280Z service books.

My questions are not the type of questions that are answered in these books.

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1. image.png

 

2. Use 27mm socket on crank to turn the engine clockwise as viewed from the front of the car. If you overshoot TDC on the crank, you can back up CCW then re-approach CW. (Don't go backwards (CCW) and stop at TDC).

 

3.  Removing plugs makes turning easier and more precise.

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Thanks 240260280 🙂

I already removed the plugs but I will try the crank bolt. That might make it easier to turn the engine.

 

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The engine aught to turn fairly smoothly with the plugs out. If it has been a while since it ran, there might be some rust scale in the bores. It is easier to turn from the crank bolt.

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Make sure you are on compression stroke if you are checking chain stretch using the cam marks. I usually find something to stick in #1 spark plug hole that will pop out easy when you are turning over the engine and it builds compression. My favorite hole stopper is a large vacuum plug shoved into the spark plug hole. Believe me , you’ll know when TDC compression is coming.

as far as the pulley marks, if you look closely , one V mark is bigger then the others , that’s TDC.

Use the crank pulley to turn the motor

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Here's a trick that's in my brain, I don't know where it came from.  Take a fan belt and place it around the damper pulley alone.  Grip both sides of the belt in one hand, tightening it in the pulley groove.  Use it as a handle to turn the crankshaft.

You could also use one of those filter wrenches that uses a rubber belt to wrap around the object to be turned.  Apparently called a "strap wrench".

I've found that the damper bolt can be hard to reach sometimes.

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Thanks guys. With your tips I figured it out. Unfortunately my timing chain needs replacing so I guess that will be one of the winter projects.

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