JJ's95B4C

I'm confused with the part of removing the timing chain and putting it back on. Every guide i've read says to bring the arrow on the hub to 12 o'clock position, which is #1 TDC, right? Here's where i'm confused. When you put it back together, again all the guides say to line up the cam/crank gear dot-to-dot. Isn't this #6 TDC? Does this matter that i'm lining up the cam for #6 TDC and cylinder #1 is at TDC? Do you have to turn the crank to get them dot to dot before removing the cam/crank gears and then put it back to #1 TDC after i'm done installing them.

Please help me out...this is my only confusion with this cam install.

Thanks!

jonaddis84

#1 and #6 are at TDC at the same time. 18436572, each piston moves is 90* from the previous so when #1 is at 0*...#8 is at 90..#4 is at 180...#3 is at 270..and #6 is at 360/0

The cam dowel pin should be at 3oclock.\

You will have to use a tool to find #1 or #6 TDC unless you did not budge the crank after removing the hub, just place a pencil or pen in the spark plug hole and rotate the crank until it stops moving and starts going down. Then line the dots on the gears up and put the hub with arrow at 12oclock.

shoebox

Pistons, that is. There are always 2 pistons at the top of their travel at the same time. Typical of a 4 stroke engine.

JJ's95B4C

I know that there are two at the top, I just thought there was a certain one that had to be on the compression stroke.

So, by what your saying, if I already have #1 at TDC(which I do, b/c the heads are off right now), then the dots should already be ligned up?

jonaddis84

I think I understand what your asking...with no cam in the engine..there is no such thing as compression and exhaust strokes or anything on the engine..thats what the cam and injectors do to make it a 4stroke.

With #1/#6 at TDC, if you line up the dots on the gears that puts it on the compression stroke "I believe"..not positive on that, but it doesnt matter.

nateh

It's easier to see that the dots are in the correct location if you line them up dot to dot (crank sprocket at 12 and cam sprocket at 6 o'clock), and you are correct that this puts #6 in firing position. If you install the opti correctly, the computer knows what's firing and it will work correctly. Look at it this way: without a cam, there isn't a way to tell which cylinder is at firing position. The cam is what determines it, and the cam keys the opti. The opti communicates with the computer, so it doesn't matter whether you go dot to dot or crank at 6, cam at 12, as long as you install the opti correctly.

jonaddis84

Correct, but theres no real way to be sure that you are at those exact positions, point made though, that as long as the dots WILL line up at 6/12 it doesnt matter where you install them at.

JJ's95B4C

If I have cylinder #1 at TDC, like the manual says, won't the cam dowel be a 9 o'clock, and the timing mark on the cam and crank be at 12 o'clock? My question is, won't it be messed up if I install it with the cam at 6 o'clock, and the crank at 12?

Either way, can I do this:

Line up the dots by turning the crank BEFORE i take off the timing assembly, put the new cam and new timing assembly in, dot to dot. Then turn the crank so that #1 is back to TDC?

If #1 is at TDC when i pull off the opti, then the dowel will be at 9 o'clock. So I have to make the dowel be at 9 o'clock again before installing it again, right?

Sorry for being such a dub ***...i just don't understand this part! lol

shoebox

I think you are missing the point. The crank makes 2 revolutions to 1 for the cam, so the crank arrow or dot is at 12 at both #1 TDC and #6 TDC. Plus as said before, it is when the cam is synched with the crank that determines which cylinder is on compression (firing).

Just put it in with the dots together and it will be perfect.

You can look at my crude video and see the relationships of the dots and dowel pin through the firing order.

AsianSensation

I guess having one more person trying to explain it might help since I was once in your shoes.

Having the hub arrow at 12:00 before you do anything will bring #1 and #6 piston at the top of their travel. Then #1 or #6 could be at TDC (compression stroke), the cam determines it. Doesn't matter as long as you have #1 and #6 piston at the top of the travel. Then do your thing (take all of the components off).

When you put it put it back together (#1 and #6 piston will still be at their top of the travel), you can either install it dot-to-dot which will put #6 cylinder at TDC or install it both dots at 12:00 which will put #1 cylinder at TDC. Most people do the dot-to-dot (maybe because it's easier to line up).

Let's assume you do the dot-to-dot (#6 will be at TDC). You have 2 choices.

1. You can leave it there and start adjusting the valves at #6 cylinder, rotate the crank 90* and adjust the valves in the next firing order, and so on until you do all eight (2 full revolutions of the crank).

2. If you want to start at #1 TDC, rotate the crank 1 full revoluton (cam rotates 1/2 the speed of the crank). This will put both dots at 12:00. Then adjust the valves at #1 cylinder, rotate the crank 90* and adjust the valves in the next firing order, and so on until you do all eight.

If you somehow move the crank during the install process making #1 and #6 piston no longer at their top of the travel, no need to get concern. The piston doesn't care/doesn't know if the if it's on the compression stroke or exhaust stroke. The cam decides that. Just bring #1 and #6 piston at their top of the travel and everything will be good. When you install the hub, you can either install it with the arrow at 6:00 or 12:00. But all people install it at 12:00 cause it's easier to see. It really doesn't matter where the arrow is at in reality (hub is nuetrally balanced) but it's nice to know when the arrow is at 12:00/6:00, #1 or #6 cylinder is at TDC. This makes your like alot easier should you need to #1/#6 TDC.

JJ's95B4C

Thanks a lot. I understand it now. The only thing that matters is that the opti is on right, and theres only one way to put that on. Thanks again. I rather have the hub with #1 at TDC since thats whats i'm accustomed to.