Huge timing chain debate!

[rio95]

Me and my buddies debated all night about how to correctly install my new timing chain. Here is the main question:

As long as the crank sprocket key and cam sprocket dot line up, are you good to go? Does this automatically mean that the number one cylinder is at TDC?

Both of my buddies said that as long as the dots line up, its good.

The more I thought about it, that doesn't seem completely true. Couldn't the dots line up of the exhaust stroke also (if installed 180 degrees off)? If this is the case, then you have to make sure that #1 is a TDC on the comp. stroke then line up the dots.

Therefore, I'm thinking that there is a one right way a and one wrong way (cam rotated 180 degrees).


what is the correct answer??

I need to know, because I installed my chain and started to second guess myself, but then when both of my buddies said as long as the dots are lined up i'm good, I put the cover and water pump back on.

 

[donjohn]

i'm gonna go w/ line up the dots and ur good to go. a 360* rotation would bring you back to the same point right? 360* rotation on the crankshaft doesn't translate to 180* of travel right?

but that mark does mean #1 cylinder should be TDC


that's what i understand from the chilton's... i've not had to do that yet

 

[rio95]

360 degrees of the crank translates to 180 degrees of the cam sprocket. I'm still unsure about what the correct answer is. I sure hope I don't have to take everything back off.


When the dots are lined up, the #1 is at TDC ( I verified), but how do I know it is on the compression stroke and not the exhaust? Or does it not matter?


I could install the #1 rockers and look at those to determine what stroke is what, because I found a description of what they do on each stroke, so you should be able to tell from that.

 

[194stang]

Your good to go. As long as the dots lined up it's good. Lining the dots puts the cam and crank in "phase" so it is on the compression stroke.

 

[rio95]

Your good to go. As long as the dots lined up it's good. Lining the dots puts the cam and crank in "phase" so it is on the compression stroke.

Alright, I hope so.


Just to check thought I think this is what I'll do when I get home:


Since I have them dot to dot right now, I'll rotate the crank counter-clockwise a bit and then rotate it clockwise towards dot to dot (piston would be going up) and if the exhaust valve starts to go down, then I would be on the exhaust stroke, thus having to rotate the the cam sprocket 180 degrees. If the exhaust valve doesn't start to go down, then I would be on the compression stroke, which means that everything is good to go.

Does this make since?

It just seems like if the crank key is facing up, then #1 could be at TDC on either the exhaust OR compression stroke, then if you rotated it 360 degrees #1 would be at the opposite stroke. If this is the case, the cam sprocket COULD be put on 180 degrees incorrectly. In other words, you could be dot to dot on the exhaust stroke (#1 at TDC), which would impact everything especially the valvetrain install. Or is this thinking completely wrong?

 

[194stang]

Ok, your making it more complicated than it is...lol...Just line up the dots on the two gears, ignore the crank key. Lining the dots guarantees it will be timed right. When the dots are lined up, it determnes which "stroke" is compression ect. You can't get it wrong as long as the dots are lined up. Put it together and go beat on it

 

[Methodical]

You should be ok. I just rebuilt the motor in my 95 Cobra. I had to get the number 1 piston at TDC on the compression to install the timing chain and the timing chain slots on the crank and the cam slots were facing one another which made the dots line up- face one another. (i.e. cam slot at 6 o'clock and the crank slot at 12 o'clock). To test, I would suggest you remove the No. 1 spark plug and put a piece of paper etc. in it and rotate the motor when its on the compression stroke the paper will pop out. Or you can put your hand over the number 1 and feel the air coming out of the spark plug hole (do this if you have a helper otherwise use my 1st suggestion) I actually learned whole lot more about a motor when I rebuilt it. Good luck. Peace

 

[rio95]

lol....alright it sounds like I good to go.


So it is impossible to have the dots line up and have #1 on the exhasut stroke!