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Timing Chain Issues

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JPSmit

JPSmit

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You may have read the first part of this in my previous engine construction post. I wanted to start a new post because I need specific advice now before I completely loose my mind. (which is easy enough done at the best of times /bcforum/images/%%GRAEMLIN_URL%%/wall.gif ) As I start, please remember

1. 1500 engine
2. high stress level
3. simple words in answer - thanks

History: I took the block in to be cleaned and they finished taking out the pistons/ cam/ crank/ timing etc at the same time. I'm now ready to put it together but I have no previous measurements.

I have found the timing marks on the Cam shaft sprocket and could not initially find the mark on the crankshaft sprocket. I think now that I have found the mark on the crankshaft sprocket. There is a light scratch (pointing outward) along one of the gear teeth that is unlike any other mark on the gear. At any rate, here is my logic, can someone confirm or correct - thanks.

1. The crankshaft sprocket installs with the thickest flange toward the engine. (the scratch is on the thinner flange side)

2. The timing marks on the sprockets must be the same across any 1500 engine. In other words, they must be interchangeable otherwise VB or Moss could not sell them individually.

3. Therefore someone out there should be able to confirm where the mark is since it should be the same on every car.

4. There is a tooth that lines up with the "key slot" on the sprocket. The scratch is on the second tooth to the right of this. (see attached picture -note I drew a line with a sharpie, the actual scratch is on the gear tooth in the same direction) Is this where yours is?

5. See attached diagram. What I can glean from the manuals is this. When the timing chain is in the correct position, there are two things that should line up. a) the two timing marks in the sprockets (blue line) and b) the two marks (one on camshaft and other on sprocket AND the outer edge of the crankshaft gear flange (red line) Is this correct?

6. In terms of assembly order, would it make sense to install the crankshaft and the camshaft and the timing chain first. Then I can move them easily without pistons to impede the crank's movement?

7. Presumably, when the engine is assembled, there is something else I could measure to ensure the timing marks are properly alligned. That is to say, if piston # 1 is TDC then some valve is open or something to that effect. what sequence would that be?

I think that is all my questions, These may be really dumb questions but I am really anxious about this. Thanks, JP /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 

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Notice how I kept my mouth shut. Good boy I am. I have only seen dimples.

But make sure they are lined up, center of crank, center of cam shaft, both marks. Got to be right, as I said check, check, check.
 
I just installed my cam with the pistons installed and it was not very difficult. BUT, you may be very unlucky and have a cam sprocket that does not have timing marks. If you are lucky then:

1) Install the crank sprocket. You may also consider temporarly installing the pulley nut to ease turning the engine.

2) Find TDC for #1 piston. If you have a dial indicator a and magnetic base, you can use them to find TDC (they are cheap at Harbor Crap Tools). If not you can eyball it. It does not have to be super precise. The intention of this is simply to get the crank sprocket timing mark into roughly the correct position.

3) Closely examine your cam sprocket. Next to one of the bolt holes there should be a dimple. You may have to look closely. It can be very difficult to find. Now Look at your cam shaft where the sprocket bolts on. Roughly 90 degrees off of the threaded holes you should see a dimple. This one can be VERY difficult to find. Use your finger tips if your eyes fail. Once you have found these two dimples, bolt the sprocket to the cam such that the dimple on the cam can be seen through the hole on the sprocket that is also marked with a dimple. You only need to bolt the sprocket on finger tight, as we are going to be removing it momentarily.

4) Feel and look around the edge of the cam sprocket. You should find/feel another dimple. It will be roughly between two teeth if I remember correctly. Once you find it, if it is difficult to see, mark it with a pen or something. Now, turn the cam until the dimple on the cam sprocket points to the timing mark on the crank sprocket. It should look as though you can draw a straight line that passes through the center of both sprockets and the timing marks.

5) Remove the cam sprocket gently so as not to turn the cam or the sprocket. Fit the chain to both sprockets and re-attach the cam sprocket to the cam. This will take SEVERAL trys before you get it right.

6) Don't be afraid to get your hands dirty. Take this info and give it a crack even if you feel like you don't fully understand it. Once you get in there, it will all make a lot more sense. If you feel insecure about something, just don't bend the lock tabs until you feel sure.
 
Agree with Jack as always. It is pretty apparent when you have it all lined up. There will be no question once it is ready to "pound" into place. Okay, don't pound. Just tap. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

P.S. Dad never uses the pound technique. I find it very soothing sometimes.
 
Take this for what it's worth. I don't have a 1500 but the book shows a punch mark instead of a scratch on both sprockets. The mark on the crank sprocket, however, does appear to be very close to where you have indicated. Sorry my scanner is broken right now so I can't send a picture.
 
On my 1500 it is a scratch on the crank sprocket and a punch on the cam.
 
Hello John-Peter,

this holds good for most engines,

with the chain on the cam and crankshaft. Turn the engine to TDC 1 and 4 (or 1 and 6). Depending which cylinder is on firing the opposite will have the inlet and exhaust lift equal if the timing is correct. This is an easy check if the head is on otherwise you will need something like two equal length rods that will sit in the cam followers.

Alec
 
Another thought is: the keyway will be straight up with #1 on TDC.
 
I looked at your message late last night after a loooong day... didn't really get what you were asking... and kinda over answered. Sorry.
 
Oh really Doc. Durn something else I didn't know.
 
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